Include the headers GLGizmoImage.cpp uses directly

Adds the includes misc-include-cleaner named: libslic3r/Point.hpp for
Vec2d, Vec3f and Transform3d, GLGizmoTextureDisplacement.hpp for the
base class, IconManager.hpp for the icon lookup, and cmath, cstddef
and cstdlib for round, size_t and abs.

docs/HLSD/keyboard-shortcuts.md

@@ -124,7 +124,9 @@ Control on the Global page, and from the `?` key on the page of the view that re
    the dialog should list it; the row's section heading is the `section_table` entry
    above it, so a new section needs an entry there too. Pick a default that does not
    collide inside its contexts; the `[Shortcuts]` tests check every default against the
-   others.
+   others. A default `KeyChord{}` leaves the action unbound: it is listed in the dialog
+   for the user to bind and matches nothing until they do, which is the honest answer
+   when every key its contexts can reach is already spoken for.
 2. Handle it in the dispatcher of its context: `MainFrame::handle_global_shortcut`,
    `GLCanvas3D::handle_shortcut`, `ObjectList::dispatch_shortcut`, or a gizmo's
    `on_tool_shortcut`. A gizmo that opens on a key sets `m_shortcut` in its constructor.

resources/images/texture_displacement_pipette.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 16 16"><g transform="rotate(-45 8 8)"><path d="M8 14.4 6.5 11.2 9.5 11.2 Z" style="fill:#009688"/><path d="M6.5 7.3 6.5 11.2 8 14.4 9.5 11.2 9.5 7.3" style="fill:none;stroke:#949494;stroke-width:0.4;stroke-linejoin:round;stroke-linecap:round"/><rect x="5.5" y="3.8" width="5" height="3.5" rx="0.9" style="fill:none;stroke:#949494;stroke-width:0.4;stroke-linejoin:round"/></g></svg>

resources/images/toolbar_image.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 16 16"><circle cx="5.9" cy="6.3" r="1.25" style="fill:#009688"/><path d="M3.4 11.9 6.4 7.7 8.8 10.7 10.4 8.6 12.6 11.9 Z" style="fill:#009688"/><rect x="2.375" y="2.375" width="11.25" height="11.25" rx="1.25" style="fill:none;stroke:#949494;stroke-width:0.4;stroke-linecap:round;stroke-linejoin:round"/></svg>

resources/shaders/110/texture_displacement_shaded.fs

@@ -51,6 +51,11 @@ uniform float      tex_aspect;
 uniform float      rotation_rad;
 uniform vec2       uv_offset;
 uniform bool       invert;
+// False means the layer places a single copy rather than repeating: outside that copy there is
+// simply no texture. DecodedHeightTexture::sample() has always returned 0 there, so the bake got
+// this right while the preview wrapped the image and showed a tiled pattern that was never going
+// to be printed.
+uniform bool       tile_enabled;
 uniform float      midlevel;      // the height that means "don't move"; needed by the parallax step
 uniform vec3       eye_model_pos; // camera position in the texture frame (world minus tex_anchor)
 uniform vec3       tex_anchor;    // the volume's origin in world space: the texture frame's origin
@@ -218,6 +223,14 @@ int nearest_palette_entry(vec3 rgb)
     return best;
 }
 
+// True where this uv has texture on it: everywhere when the layer repeats, and only inside the
+// single placed copy when it does not. The bake's own sampler draws the same line (see
+// DecodedHeightTexture::sample), so the preview now stops at the same edge it does.
+bool in_tile(vec2 uv)
+{
+    return tile_enabled || (uv.x >= 0.0 && uv.x <= 1.0 && uv.y >= 0.0 && uv.y <= 1.0);
+}
+
 void main()
 {
     if (any(lessThan(clipping_planes_dots, ZERO)))
@@ -243,9 +256,9 @@ void main()
                     ? vec2(dot(island_delta_lin.xy, vertex_uv), dot(island_delta_lin.zw, vertex_uv)) + island_delta_tr
                     : vertex_uv;
         color_uv = uv;
-        have_uv  = true;
+        have_uv  = in_tile(uv);
         float h = texture2D(height_tex, uv).r;
-        float k = (invert ? -1.0 : 1.0) * depth_mm * clamp(weight, 0.0, 1.0);
+        float k = (invert ? -1.0 : 1.0) * depth_mm * clamp(weight, 0.0, 1.0) * (have_uv ? 1.0 : 0.0);
         vec3  sigmaS = dFdx(world_pos.xyz);
         vec3  sigmaT = dFdy(world_pos.xyz);
         vec3  R1 = cross(sigmaT, triangle_normal);
@@ -262,10 +275,12 @@ void main()
 
         // Parallax occlusion mapping: march the view ray through the height shell and shade at the
         // first point where it drops below the displaced surface (see header).
-        float amp      = (invert ? -1.0 : 1.0) * depth_mm * clamp(weight, 0.0, 1.0);
+        // uv first: outside a single placed copy there is no shell to march through.
+        vec2  uv       = project_uv(tex_pos, triangle_normal);
+        float amp      = (invert ? -1.0 : 1.0) * depth_mm * clamp(weight, 0.0, 1.0) *
+                         (in_tile(uv) ? 1.0 : 0.0);
         vec3  view_dir = normalize(eye_model_pos - tex_pos);
         float v_dot_n  = dot(view_dir, triangle_normal);
-        vec2  uv       = project_uv(tex_pos, triangle_normal);
 
         // The shell the displaced surface lives inside, as signed heights along the normal. Taken from
         // both ends of h in [0, 1] so it stays correct for an inverted layer or a raised midlevel,
@@ -302,7 +317,7 @@ void main()
         }
 
         color_uv = uv; // after the parallax march, so colour and relief stay registered
-        have_uv  = true;
+        have_uv  = in_tile(uv);
 
         float hL = texture2D(height_tex, uv - vec2(height_tex_texel.x, 0.0)).r;
         float hR = texture2D(height_tex, uv + vec2(height_tex_texel.x, 0.0)).r;
@@ -311,7 +326,8 @@ void main()
 
         vec2 dh_duv = vec2((hR - hL) / (2.0 * height_tex_texel.x), (hU - hD) / (2.0 * height_tex_texel.y));
         float inv_tiling = (tiling_scale > 1e-6) ? (1.0 / tiling_scale) : 1.0;
-        float amplitude  = (invert ? -1.0 : 1.0) * depth_mm * inv_tiling * clamp(weight, 0.0, 1.0);
+        float amplitude  = (invert ? -1.0 : 1.0) * depth_mm * inv_tiling * clamp(weight, 0.0, 1.0) *
+                           (have_uv ? 1.0 : 0.0);
 
         float cs = cos(rotation_rad);
         float sn = sin(rotation_rad);
@@ -341,7 +357,12 @@ void main()
     // Only the albedo - the specular term (intensity.y) stays white - so a coloured fragment reads as
     // the same material under the same light, and the relief this preview exists to show is unaffected.
     vec3 albedo = uniform_color.rgb;
-    if (palette_count > 0 && has_color_tex && have_uv && weight > 0.0)
-        albedo = palette_rgb[nearest_palette_entry(texture2D(color_tex, color_uv).rgb)];
+    // The fourth channel is coverage: where the picture is not there, the surface keeps its own
+    // colour rather than being painted the black that a transparent texel's rgb reads as.
+    if (palette_count > 0 && has_color_tex && have_uv && weight > 0.0) {
+        vec4 tex_rgba = texture2D(color_tex, color_uv);
+        if (tex_rgba.a >= 0.5)
+            albedo = palette_rgb[nearest_palette_entry(tex_rgba.rgb)];
+    }
     gl_FragColor = vec4(vec3(intensity.y) + albedo * intensity.x, uniform_color.a);
 }

resources/shaders/140/texture_displacement_shaded.fs

@@ -110,6 +110,11 @@ uniform float      tex_aspect;
 uniform float      rotation_rad;
 uniform vec2       uv_offset;
 uniform bool       invert;
+// False means the layer places a single copy rather than repeating: outside that copy there is
+// simply no texture. DecodedHeightTexture::sample() has always returned 0 there, so the bake got
+// this right while the preview wrapped the image and showed a tiled pattern that was never going
+// to be printed.
+uniform bool       tile_enabled;
 uniform float      midlevel;      // the height that means "don't move"; needed by the parallax step
 uniform vec3       eye_model_pos; // camera position in the texture frame (world minus tex_anchor)
 uniform vec3       tex_anchor;    // the volume's origin in world space: the texture frame's origin
@@ -284,6 +289,14 @@ int nearest_palette_entry(vec3 rgb)
     return best;
 }
 
+// True where this uv has texture on it: everywhere when the layer repeats, and only inside the
+// single placed copy when it does not. The bake's own sampler draws the same line (see
+// DecodedHeightTexture::sample), so the preview now stops at the same edge it does.
+bool in_tile(vec2 uv)
+{
+    return tile_enabled || (uv.x >= 0.0 && uv.x <= 1.0 && uv.y >= 0.0 && uv.y <= 1.0);
+}
+
 void main()
 {
     if (any(lessThan(clipping_planes_dots, ZERO)))
@@ -321,9 +334,9 @@ void main()
                     ? vec2(dot(island_delta_lin.xy, vertex_uv), dot(island_delta_lin.zw, vertex_uv)) + island_delta_tr
                     : vertex_uv;
         color_uv = uv;
-        have_uv  = true;
+        have_uv  = in_tile(uv);
         float h = texture(height_tex, uv).r;
-        float k = (invert ? -1.0 : 1.0) * depth_mm * clamp(weight, 0.0, 1.0);
+        float k = (invert ? -1.0 : 1.0) * depth_mm * clamp(weight, 0.0, 1.0) * (have_uv ? 1.0 : 0.0);
         vec3  sigmaS = dFdx(world_pos.xyz);
         vec3  sigmaT = dFdy(world_pos.xyz);
         vec3  R1 = cross(sigmaT, triangle_normal);
@@ -343,10 +356,12 @@ void main()
 
         // Parallax occlusion mapping: march the view ray through the height shell and shade at the
         // first point where it drops below the displaced surface (see header).
-        float amp      = (invert ? -1.0 : 1.0) * depth_mm * clamp(weight, 0.0, 1.0);
+        // uv first: outside a single placed copy there is no shell to march through.
+        vec2  uv       = project_uv(tex_pos, triangle_normal);
+        float amp      = (invert ? -1.0 : 1.0) * depth_mm * clamp(weight, 0.0, 1.0) *
+                         (in_tile(uv) ? 1.0 : 0.0);
         vec3  view_dir = normalize(eye_model_pos - tex_pos);
         float v_dot_n  = dot(view_dir, triangle_normal);
-        vec2  uv       = project_uv(tex_pos, triangle_normal);
 
         // The shell the displaced surface lives inside, as signed heights along the normal. Taken from
         // both ends of h in [0, 1] so it stays correct for an inverted layer or a raised midlevel,
@@ -383,7 +398,7 @@ void main()
         }
 
         color_uv = uv; // after the parallax march, so colour and relief stay registered
-        have_uv  = true;
+        have_uv  = in_tile(uv);
 
         float hL = texture(height_tex, uv - vec2(height_tex_texel.x, 0.0)).r;
         float hR = texture(height_tex, uv + vec2(height_tex_texel.x, 0.0)).r;
@@ -396,7 +411,8 @@ void main()
         // uv -> mm is 1/tiling_scale for the triplanar projection, so this turns the uv-space
         // gradient into a real surface slope.
         float inv_tiling = (tiling_scale > 1e-6) ? (1.0 / tiling_scale) : 1.0;
-        float amplitude  = (invert ? -1.0 : 1.0) * depth_mm * inv_tiling * clamp(weight, 0.0, 1.0);
+        float amplitude  = (invert ? -1.0 : 1.0) * depth_mm * inv_tiling * clamp(weight, 0.0, 1.0) *
+                           (have_uv ? 1.0 : 0.0);
         // uv was rotated by project_uv() while t/b are the unrotated model axes, so rotate the
         // gradient back into the axes' frame.
         float cs = cos(rotation_rad);
@@ -429,7 +445,12 @@ void main()
     // Only the albedo - the specular term (intensity.y) stays white - so a coloured fragment reads as
     // the same material under the same light, and the relief this preview exists to show is unaffected.
     vec3 albedo = uniform_color.rgb;
-    if (palette_count > 0 && has_color_tex && have_uv && weight > 0.0)
-        albedo = palette_rgb[nearest_palette_entry(texture(color_tex, color_uv).rgb)];
+    // The fourth channel is coverage: where the picture is not there, the surface keeps its own
+    // colour rather than being painted the black that a transparent texel's rgb reads as.
+    if (palette_count > 0 && has_color_tex && have_uv && weight > 0.0) {
+        vec4 tex_rgba = texture(color_tex, color_uv);
+        if (tex_rgba.a >= 0.5)
+            albedo = palette_rgb[nearest_palette_entry(tex_rgba.rgb)];
+    }
     out_color = vec4(vec3(intensity.y) + albedo * intensity.x, uniform_color.a);
 }

src/libslic3r/TextureDisplacement.cpp

@@ -115,6 +115,20 @@ float DecodedHeightTexture::sample(const Vec2f &uv, bool tile_enabled, TextureTi
     return top * (1.f - ty) + bottom * ty;
 }
 
+float DecodedHeightTexture::sample_alpha(const Vec2f &uv, bool tile_enabled, TextureTileMethod tile_method) const
+{
+    TexelTap tap;
+    if (!has_alpha())
+        return 1.f; // no coverage plane means the picture is everywhere, which is the usual case
+    if (!texel_tap(uv, tile_enabled, tile_method, tap))
+        return 0.f;
+
+    auto at = [this](int x, int y) { return float(alpha[size_t(y) * size_t(width) + size_t(x)]) / 255.f; };
+    const float top    = at(tap.x0, tap.y0) * (1.f - tap.tx) + at(tap.x1, tap.y0) * tap.tx;
+    const float bottom = at(tap.x0, tap.y1) * (1.f - tap.tx) + at(tap.x1, tap.y1) * tap.tx;
+    return top * (1.f - tap.ty) + bottom * tap.ty;
+}
+
 Vec3f DecodedHeightTexture::sample_color(const Vec2f &uv, bool tile_enabled, TextureTileMethod tile_method) const
 {
     TexelTap tap;
@@ -261,6 +275,272 @@ bool height_texture_has_color(const TextureDisplacementLayer &layer)
     return decode_height_texture(layer).has_color();
 }
 
+namespace {
+// Unsharp mask over the colour: blur a copy and push each texel away from it. The blur is the same
+// sliding-window helper the Smoothing slider uses, run per channel, so the cost is the image size
+// rather than the image size times the radius.
+//
+// Worth having here for a reason it would not be in a photo editor: the picture is about to be
+// reduced to a handful of flat colours, and a soft edge between two of them quantizes into a ragged
+// band of both. Sharpening first makes that boundary land in one place.
+void sharpen_rgb(DecodedHeightTexture &tex, float amount)
+{
+    if (!tex.has_color() || amount <= 0.f)
+        return;
+    const size_t n = size_t(tex.width) * size_t(tex.height);
+    // A small radius, scaled with the image so a 4k picture is not sharpened a tenth as hard as a
+    // 512 one. Deliberately not tied to `amount`: that is how much, this is how wide.
+    const int radius = std::max(1, int(std::lround(double(std::min(tex.width, tex.height)) / 512.0)));
+    const float k    = std::clamp(amount, 0.f, 1.f) * 1.5f;
+
+    std::vector<uint8_t> plane(n);
+    for (int c = 0; c < 3; ++c) {
+        for (size_t i = 0; i < n; ++i)
+            plane[i] = tex.rgb[i * 3 + size_t(c)];
+        smooth_height_pixels_box(plane, tex.width, tex.height, radius);
+        for (size_t i = 0; i < n; ++i) {
+            const float sharp = float(tex.rgb[i * 3 + size_t(c)]) + k * (float(tex.rgb[i * 3 + size_t(c)]) - float(plane[i]));
+            tex.rgb[i * 3 + size_t(c)] = uint8_t(std::lround(std::clamp(sharp, 0.f, 255.f)));
+        }
+    }
+}
+
+// Reduces the picture to at most `count` colours, by k-means in RGB.
+//
+// "At most": two of the chosen colours can still match the same filament, in which case the print
+// uses fewer. The guarantee runs the right way round, which is the one that matters - asking for
+// three colours cannot produce four.
+//
+// k-means rather than a fixed palette or an even split of the luma range, because the useful
+// question is which colours this picture is actually made of. A tartan asks for its own handful of
+// greens and reds; posterizing the range would hand it eight shades of mud instead. The clustering
+// runs over a coarse histogram, not over the pixels: at 1024 x 1024 that is 4096 weighted points
+// instead of a million, which is what makes it cheap enough to sit on a slider.
+void reduce_colors(DecodedHeightTexture &tex, int count)
+{
+    if (!tex.has_color() || count < 2 || count > 64)
+        return;
+    const size_t n = size_t(tex.width) * size_t(tex.height);
+
+    // 16 levels per channel, each bin keeping the mean of what fell in it, so a colour is not
+    // snapped to a bin corner before the clustering has had a say.
+    struct Bin { double r = 0, g = 0, b = 0; uint32_t n = 0; };
+    std::vector<Bin> bins(size_t(16 * 16 * 16));
+    for (size_t i = 0; i < n; ++i) {
+        const uint8_t r = tex.rgb[i * 3], g = tex.rgb[i * 3 + 1], b = tex.rgb[i * 3 + 2];
+        Bin &bin = bins[(size_t(r >> 4) << 8) | (size_t(g >> 4) << 4) | size_t(b >> 4)];
+        bin.r += r; bin.g += g; bin.b += b; ++bin.n;
+    }
+    struct Point { float c[3]; double w; };
+    std::vector<Point> pts;
+    pts.reserve(bins.size());
+    for (const Bin &bin : bins)
+        if (bin.n > 0)
+            pts.push_back({ { float(bin.r / bin.n), float(bin.g / bin.n), float(bin.b / bin.n) }, double(bin.n) });
+    if (pts.size() <= size_t(count))
+        return; // already no more colours than asked for
+
+    // Seeded the k-means++ way, deterministically: the heaviest point first, then each next one is
+    // whichever point is furthest from everything chosen so far, weighted by how much of the image
+    // it is. Picking the N fullest bins instead would put every centre inside the one dominant
+    // colour of a picture that has one.
+    std::vector<std::array<float, 3>> centre;
+    {
+        size_t best = 0;
+        for (size_t i = 1; i < pts.size(); ++i)
+            if (pts[i].w > pts[best].w)
+                best = i;
+        centre.push_back({ pts[best].c[0], pts[best].c[1], pts[best].c[2] });
+        std::vector<double> d2(pts.size(), std::numeric_limits<double>::max());
+        while (int(centre.size()) < count) {
+            const auto &last = centre.back();
+            double      top  = -1.0;
+            size_t      pick = 0;
+            for (size_t i = 0; i < pts.size(); ++i) {
+                const double dr = pts[i].c[0] - last[0], dg = pts[i].c[1] - last[1], db = pts[i].c[2] - last[2];
+                d2[i] = std::min(d2[i], dr * dr + dg * dg + db * db);
+                if (const double score = d2[i] * pts[i].w; score > top) {
+                    top  = score;
+                    pick = i;
+                }
+            }
+            if (top <= 0.0)
+                break; // fewer distinct colours than asked for
+            centre.push_back({ pts[pick].c[0], pts[pick].c[1], pts[pick].c[2] });
+        }
+    }
+
+    // Lloyd's algorithm over the weighted bins. Twelve passes: on a histogram this coarse it has
+    // stopped moving well before that, and a fixed count keeps the slider's cost predictable.
+    const int k = int(centre.size());
+    for (int iter = 0; iter < 12; ++iter) {
+        std::vector<std::array<double, 3>> sum(size_t(k), { 0.0, 0.0, 0.0 });
+        std::vector<double>                wsum(size_t(k), 0.0);
+        for (const Point &p : pts) {
+            int    best = 0;
+            double bd   = std::numeric_limits<double>::max();
+            for (int c = 0; c < k; ++c) {
+                const double dr = p.c[0] - centre[size_t(c)][0], dg = p.c[1] - centre[size_t(c)][1],
+                             db = p.c[2] - centre[size_t(c)][2];
+                if (const double d = dr * dr + dg * dg + db * db; d < bd) { bd = d; best = c; }
+            }
+            for (int ch = 0; ch < 3; ++ch)
+                sum[size_t(best)][size_t(ch)] += double(p.c[ch]) * p.w;
+            wsum[size_t(best)] += p.w;
+        }
+        for (int c = 0; c < k; ++c)
+            if (wsum[size_t(c)] > 0.0)
+                for (int ch = 0; ch < 3; ++ch)
+                    centre[size_t(c)][size_t(ch)] = float(sum[size_t(c)][size_t(ch)] / wsum[size_t(c)]);
+    }
+
+    // Every texel takes its nearest centre. Parallel by rows, as the tonal pass is.
+    const size_t rows = size_t(tex.height), cols = size_t(tex.width);
+    tbb::parallel_for(tbb::blocked_range<size_t>(0, rows), [&](const tbb::blocked_range<size_t> &range) {
+        for (size_t y = range.begin(); y < range.end(); ++y)
+            for (size_t x = 0; x < cols; ++x) {
+                uint8_t *px   = tex.rgb.data() + (y * cols + x) * 3;
+                int      best = 0;
+                float    bd   = std::numeric_limits<float>::max();
+                for (int c = 0; c < k; ++c) {
+                    const float dr = float(px[0]) - centre[size_t(c)][0], dg = float(px[1]) - centre[size_t(c)][1],
+                                db = float(px[2]) - centre[size_t(c)][2];
+                    if (const float d = dr * dr + dg * dg + db * db; d < bd) { bd = d; best = c; }
+                }
+                for (int ch = 0; ch < 3; ++ch)
+                    px[size_t(ch)] = uint8_t(std::lround(std::clamp(centre[size_t(best)][size_t(ch)], 0.f, 255.f)));
+            }
+    });
+}
+
+// Keys one colour out, so a logo on a white card prints as the logo and the object's own colour
+// shows through the rest.
+//
+// The corners are the default because a background that does not reach all four of them is not a
+// background, and that makes the common case one click; the median of the four is taken so a single
+// stray corner cannot decide it. The panel's dropper and swatch override it when the picture needs
+// something else keyed out.
+void remove_background(DecodedHeightTexture &tex, const TextureDisplacementLayer &layer)
+{
+    if (!tex.has_color() || !layer.bg_remove || tex.width < 2 || tex.height < 2)
+        return;
+    const size_t n = size_t(tex.width) * size_t(tex.height);
+    float key[3];
+    if (layer.bg_from_corners) {
+        const size_t corner[4] = { 0, size_t(tex.width) - 1, (size_t(tex.height) - 1) * size_t(tex.width),
+                                   n - 1 };
+        for (int c = 0; c < 3; ++c) {
+            std::array<float, 4> v{};
+            for (int i = 0; i < 4; ++i)
+                v[size_t(i)] = float(tex.rgb[corner[i] * 3 + size_t(c)]);
+            std::sort(v.begin(), v.end());
+            key[c] = 0.5f * (v[1] + v[2]);
+        }
+    } else {
+        for (int c = 0; c < 3; ++c)
+            key[c] = std::clamp(layer.bg_color[c], 0.f, 1.f) * 255.f;
+    }
+    // Euclidean in 0..255 RGB, against a tolerance scaled to the diagonal of that cube, so the
+    // slider reads as "how different from the background still counts as background".
+    const float limit = std::clamp(layer.bg_tolerance, 0.f, 1.f) * 441.67f;
+    if (!tex.has_alpha())
+        tex.alpha.assign(n, 255);
+    for (size_t i = 0; i < n; ++i) {
+        const float dr = float(tex.rgb[i * 3]) - key[0];
+        const float dg = float(tex.rgb[i * 3 + 1]) - key[1];
+        const float db = float(tex.rgb[i * 3 + 2]) - key[2];
+        if (std::sqrt(dr * dr + dg * dg + db * db) <= limit)
+            tex.alpha[i] = 0;
+    }
+}
+} // namespace
+
+bool has_color_adjustments(const TextureDisplacementLayer &layer)
+{
+    return layer.brightness != 0.f || layer.contrast != 0.f || layer.saturation != 1.f ||
+           layer.gamma != 1.f || layer.color_invert || layer.hue != 0.f || layer.sharpness > 0.f ||
+           layer.color_count >= 2 || layer.bg_remove;
+}
+
+void apply_color_adjustments(DecodedHeightTexture &tex, const TextureDisplacementLayer &layer)
+{
+    if (!tex.has_color() || !has_color_adjustments(layer))
+        return;
+
+    // A contrast of -1 collapses the image to mid grey and +1 doubles the slope about it, which is
+    // the range a single slider can offer without a scale nobody can read off the handle.
+    const float slope  = 1.f + std::clamp(layer.contrast, -1.f, 1.f);
+    const float bright = std::clamp(layer.brightness, -1.f, 1.f);
+    const float sat    = std::max(0.f, layer.saturation);
+    const float inv_g  = 1.f / std::max(0.01f, layer.gamma);
+    const bool  negate = layer.color_invert;
+    // Hue is a rotation of the colour about the grey axis. Rodrigues' formula about (1,1,1)/sqrt(3),
+    // then the luma is put back exactly (the rotation preserves R+G+B, not the Rec. 709 weighting),
+    // so turning the wheel changes which filament an area matches without also changing how light
+    // it is.
+    const float hue_rad = layer.hue * float(M_PI) / 180.f;
+    const float hue_cos = std::cos(hue_rad), hue_sin = std::sin(hue_rad);
+    const bool  rotate  = layer.hue != 0.f;
+    constexpr float LW[3] = { 0.2126f, 0.7152f, 0.0722f }; // Rec. 709 luma
+
+    // Each output byte depends only on its own pixel, so the rows are independent. At 1024 x 1024
+    // this runs on every preview rebuild and every bake, which is what makes it worth splitting.
+    const size_t rows = size_t(tex.height);
+    const size_t cols = size_t(tex.width);
+    tbb::parallel_for(tbb::blocked_range<size_t>(0, rows), [&](const tbb::blocked_range<size_t> &range) {
+        for (size_t y = range.begin(); y < range.end(); ++y) {
+            uint8_t *row = tex.rgb.data() + y * cols * 3;
+            for (size_t x = 0; x < cols; ++x) {
+                uint8_t *px = row + x * 3;
+                float    c[3];
+                for (int k = 0; k < 3; ++k) {
+                    float v = float(px[k]) * (1.f / 255.f);
+                    v       = std::pow(v, inv_g);
+                    v       = (v - 0.5f) * slope + 0.5f;
+                    v      += bright;
+                    c[k]    = v;
+                }
+                if (rotate) {
+                    const float luma = LW[0] * c[0] + LW[1] * c[1] + LW[2] * c[2];
+                    // The component of the colour across the grey axis, which is what a hue is.
+                    const float mean = (c[0] + c[1] + c[2]) / 3.f;
+                    const float p[3] = { c[0] - mean, c[1] - mean, c[2] - mean };
+                    // k x p for the unit grey axis k = (1,1,1)/sqrt(3).
+                    constexpr float INV_SQRT3 = 0.57735027f;
+                    const float     x[3]      = { INV_SQRT3 * (p[1] - p[2]), INV_SQRT3 * (p[2] - p[0]),
+                                                  INV_SQRT3 * (p[0] - p[1]) };
+                    for (int k = 0; k < 3; ++k)
+                        c[k] = mean + p[k] * hue_cos + x[k] * hue_sin;
+                    const float luma_now = LW[0] * c[0] + LW[1] * c[1] + LW[2] * c[2];
+                    for (float &v : c)
+                        v += luma - luma_now;
+                }
+                if (sat != 1.f) {
+                    // Rec. 709 luma, the same weights the rest of the colour path uses to decide
+                    // what counts as light and dark.
+                    const float luma = LW[0] * c[0] + LW[1] * c[1] + LW[2] * c[2];
+                    for (float &v : c)
+                        v = luma + (v - luma) * sat;
+                }
+                for (int k = 0; k < 3; ++k) {
+                    float v = std::clamp(c[k], 0.f, 1.f);
+                    if (negate)
+                        v = 1.f - v;
+                    px[k] = uint8_t(std::lround(v * 255.f));
+                }
+            }
+        }
+    });
+
+    // Sharpen, threshold and the background key are all passes over the whole image rather than
+    // per-texel arithmetic, so they come after the loop above and in this order: sharpening a
+    // thresholded image would only ring along the one edge it has left, and the key has to read the
+    // colours the user is actually looking at.
+    sharpen_rgb(tex, layer.sharpness);
+    reduce_colors(tex, layer.color_count);
+    remove_background(tex, layer);
+}
+
 DecodedHeightTexture decode_height_texture(const TextureDisplacementLayer &layer)
 {
     DecodedHeightTexture result;
@@ -313,6 +593,10 @@ DecodedHeightTexture decode_height_texture(const TextureDisplacementLayer &layer
             result.height = h;
             result.pixels.resize(size_t(w) * size_t(h));
             result.rgb.resize(size_t(w) * size_t(h) * 3);
+            // A fourth channel is coverage, and it is the only thing that can say "the picture is
+            // not here" as opposed to "the picture is black here". Kept only when the source has it.
+            if (bpp >= 4)
+                result.alpha.resize(size_t(w) * size_t(h));
             // decode_colored_png() hands its buffer back bottom-up - it is shared with the CLI's
             // plate-thumbnail loader, which expects that - while this type, and decode_png()'s
             // grayscale path above, are top-to-bottom. Reverse the rows on the way in so a colour
@@ -326,6 +610,8 @@ DecodedHeightTexture decode_height_texture(const TextureDisplacementLayer &layer
                     result.rgb[dst * 3 + 1] = g;
                     result.rgb[dst * 3 + 2] = b;
                     result.pixels[dst] = uint8_t(std::lround(0.299 * r + 0.587 * g + 0.114 * b));
+                    if (bpp >= 4)
+                        result.alpha[dst] = src[3];
                 }
         }
 
@@ -1859,10 +2145,14 @@ bool sample_layer_color(const DecodedHeightTexture &texture, const TextureDispla
     // Outside a non-tiled placement there is no texture at all - the same hard edge sample() gives the
     // height. Checked explicitly because sample_color() reports it as black, which is a real colour.
     auto covered = [&](const Vec2f &planar) {
-        if (layer.tile_enabled)
-            return true;
         const Vec2f uv = xf(planar);
-        return uv.x() >= 0.f && uv.x() < 1.f && uv.y() >= 0.f && uv.y() < 1.f;
+        if (!layer.tile_enabled && !(uv.x() >= 0.f && uv.x() < 1.f && uv.y() >= 0.f && uv.y() < 1.f))
+            return false;
+        // Where the picture is transparent there is no colour to print, which is the same answer as
+        // being outside the placement - not black, which is a colour. Half coverage counts as
+        // covered: a triangle prints in one filament either way, so the only useful question is
+        // which side of the edge it falls on.
+        return texture.sample_alpha(uv, layer.tile_enabled, layer.tile_method) >= 0.5f;
     };
 
     if (lscm_uv != nullptr) {
@@ -3241,9 +3531,13 @@ std::shared_ptr<std::vector<PreparedLayer>> prepare_sampleable_layers(
         const TriangleSelector::TriangleSplittingData &data = facets_data[size_t(layer->slot)];
         if (data.triangles_to_split.empty())
             continue;
-        const DecodedHeightTexture tex = decode_height_texture(*layer);
+        DecodedHeightTexture tex = decode_height_texture(*layer);
         if (tex.empty() || (need_color && !tex.has_color()))
             continue;
+        // The one place the bake and every preview job read a layer's colour from, so correcting it
+        // here is what keeps what the panel shows and what the bake prints the same image.
+        if (need_color)
+            apply_color_adjustments(tex, *layer);
 
         TriangleSelector selector(selector_mesh);
         selector.deserialize(data, false);

src/libslic3r/TextureDisplacement.hpp

@@ -293,6 +293,32 @@ struct TextureDisplacementLayer
     // for the boundary to be drawn on.
     bool color_enabled = false;
 
+    // Colour correction, applied to the image's RGB before it is matched against the filaments and
+    // before the preview quantizes it. Never to the height: the relief is what the grayscale says,
+    // and a brightness slider has no business moving geometry. The defaults below are the identity,
+    // so a layer that never meets the Image tool behaves exactly as it did.
+    float brightness   = 0.f;  // -1 .. 1, added last, after contrast
+    float contrast     = 0.f;  // -1 .. 1, pivoted on mid grey; -1 flattens to grey, 1 doubles the slope
+    float hue          = 0.f;  // -180 .. 180 degrees, rotated about the grey axis at constant luma
+    float sharpness    = 0.f;  //  0 .. 1 unsharp mask amount, 0 is off
+    // How many colours the picture is allowed to use, 0 for as many as it likes. Reduced by k-means
+    // in RGB before the filaments are matched, so the result uses at most this many of them: 2 for a
+    // logo that should be two flat colours, 4 or 5 for a poster, off for a photograph.
+    int   color_count  = 0;    // 0, or 2 .. 12
+    // Leaves the background of a picture unprinted, so the object's own colour shows through instead
+    // of a slab of white behind a logo. Texels the source image marked transparent always count;
+    // `bg_remove` additionally keys out one colour.
+    bool  bg_remove    = false;
+    float bg_tolerance = 0.15f; // 0 .. 1, distance from the keyed colour that still counts as background
+    // The colour keyed out. Taken from the median of the picture's four corners while
+    // `bg_from_corners` is set, which is right for nearly every logo on a flat card; the panel's
+    // dropper and swatch clear it and put a colour of the user's own here.
+    bool  bg_from_corners = true;
+    float bg_color[3]     = { 1.f, 1.f, 1.f };
+    float saturation   = 1.f;  //  0 .. 2, 1 leaves it alone, 0 is grayscale
+    float gamma        = 1.f;  // 0.2 .. 5, 1 leaves it alone; above 1 lifts the midtones
+    bool  color_invert = false; // negative of the colour, as opposed to `invert` which flips relief
+
     bool empty() const { return !image_data || image_data->empty(); }
 
     template<class Archive> void save(Archive &ar) const
@@ -302,7 +328,9 @@ struct TextureDisplacementLayer
            static_cast<int>(tile_method), static_cast<int>(projection_method), lscm_seam_angle_deg, islands,
            static_cast<int>(blend_mode), midlevel, island_padding_mm, lscm_seam_edges, view_project_right,
            view_project_up, smoothing, edge_smoothing, edge_smoothing_amount, auto_connect_islands, island_groups,
-           lscm_uv_overrides, view_project_projective, view_project_matrix, color_enabled);
+           lscm_uv_overrides, view_project_projective, view_project_matrix, color_enabled, brightness,
+           contrast, saturation, gamma, color_invert, hue, sharpness, color_count, bg_remove,
+           bg_tolerance, bg_from_corners, bg_color[0], bg_color[1], bg_color[2]);
     }
     template<class Archive> void load(Archive &ar)
     {
@@ -314,7 +342,8 @@ struct TextureDisplacementLayer
            tile_method_int, projection_method_int, lscm_seam_angle_deg, islands, blend_mode_int, midlevel,
            island_padding_mm, lscm_seam_edges, view_project_right, view_project_up, smoothing, edge_smoothing,
            edge_smoothing_amount, auto_connect_islands, island_groups, lscm_uv_overrides, view_project_projective,
-           view_project_matrix, color_enabled);
+           view_project_matrix, color_enabled, brightness, contrast, saturation, gamma, color_invert, hue, sharpness,
+           color_count, bg_remove, bg_tolerance, bg_from_corners, bg_color[0], bg_color[1], bg_color[2]);
         image_data        = blob.empty() ? nullptr : std::make_shared<std::vector<unsigned char>>(blob.begin(), blob.end());
         tile_method       = static_cast<TextureTileMethod>(tile_method_int);
         projection_method = static_cast<TextureProjectionMethod>(projection_method_int);
@@ -448,11 +477,19 @@ struct DecodedHeightTexture
     // has_color() is what the whole colour feature keys off: a layer set to colour a model with a
     // grayscale texture on it simply colours nothing.
     std::vector<uint8_t> rgb;
+    // Coverage: 0 where the picture is not there at all, 255 where it is fully there. Empty when the
+    // source image had no alpha and nothing has keyed a background out, which is the common case and
+    // means "opaque everywhere". Distinct from a black texel, which is a colour.
+    std::vector<uint8_t> alpha;
     int width  = 0;
     int height = 0;
 
     bool empty() const { return width <= 0 || height <= 0 || pixels.empty(); }
     bool has_color() const { return !empty() && rgb.size() == size_t(width) * size_t(height) * 3; }
+    bool has_alpha() const { return !empty() && alpha.size() == size_t(width) * size_t(height); }
+    // Coverage at a uv, bilinear, in [0, 1]. 1 everywhere when there is no alpha plane.
+    float sample_alpha(const Vec2f &uv, bool tile_enabled = true,
+                       TextureTileMethod tile_method = TextureTileMethod::Repeat) const;
     // Bilinearly sampled height in [0, 1] at a normalized uv coordinate. When tile_enabled is false,
     // a uv outside [0, 1) samples as 0 - the texture simply is not there, rather than its border
     // row/column being smeared outward forever (which is what clamping the coordinate would do, and
@@ -489,6 +526,19 @@ DecodedHeightTexture decode_height_texture(const TextureDisplacementLayer &layer
 // texture - cheap enough to ask every frame. Smoothing does not change it, so the raw decode is what is read.
 bool height_texture_has_color(const TextureDisplacementLayer &layer);
 
+// True when `layer`'s colour correction is anything other than the identity, so callers can skip
+// both the work and the cache invalidation it would otherwise force.
+bool has_color_adjustments(const TextureDisplacementLayer &layer);
+
+// Applies that correction to an already decoded image, in place, to `rgb` only. Order is gamma,
+// contrast, brightness, saturation, invert, each clamped back into range - the order a photo editor
+// applies them in, and the one that keeps contrast pivoted on mid grey rather than on a brightness
+// the slider has already moved.
+//
+// Deliberately not folded into decode_height_texture(): that result is cached per image, shared by
+// every layer using the same file, and keyed on the image bytes alone.
+void apply_color_adjustments(DecodedHeightTexture &tex, const TextureDisplacementLayer &layer);
+
 // Maps a linear RGB colour in [0, 1] to an index into the caller's palette, or -1 for "no colour".
 //
 // Deliberately a callback rather than a function here: matching a colour to a filament is a

src/slic3r/CMakeLists.txt

@@ -186,6 +186,8 @@ set(SLIC3R_GUI_SOURCES
     GUI/Gizmos/GLGizmoFlatten.hpp
     GUI/Gizmos/GLGizmoFuzzySkin.cpp
     GUI/Gizmos/GLGizmoFuzzySkin.hpp
+    GUI/Gizmos/GLGizmoImage.cpp
+    GUI/Gizmos/GLGizmoImage.hpp
     GUI/Gizmos/GLGizmoMeasure.cpp
     GUI/Gizmos/GLGizmoMeasure.hpp
     GUI/Gizmos/GLGizmoMeshBoolean.cpp

src/slic3r/GUI/Gizmos/GLGizmoImage.cpp

@@ -0,0 +1,891 @@
+#include "GLGizmoImage.hpp"
+
+#include "libslic3r/Model.hpp"
+#include "libslic3r/Point.hpp"
+#include "libslic3r/TextureDisplacement.hpp"
+#include "libslic3r/format.hpp"
+
+#include "slic3r/GUI/Camera.hpp"
+#include "slic3r/GUI/GLCanvas3D.hpp"
+#include "slic3r/GUI/GLTexture.hpp"
+#include "slic3r/GUI/GUI.hpp"
+#include "slic3r/GUI/GUI_App.hpp"
+#include "slic3r/GUI/I18N.hpp"
+#include "slic3r/GUI/IconManager.hpp"
+#include "slic3r/GUI/ImGuiWrapper.hpp"
+#include "slic3r/GUI/Plater.hpp"
+#include "slic3r/GUI/TextureLibrary.hpp"
+#include "slic3r/GUI/Shortcuts.hpp"
+#include "slic3r/GUI/Gizmos/GLGizmoPainterBase.hpp"
+#include "slic3r/GUI/Gizmos/GLGizmoTextureDisplacement.hpp"
+#include "slic3r/GUI/Gizmos/GLGizmoUtils.hpp"
+#include "slic3r/GUI/Jobs/Worker.hpp"
+
+#include <algorithm>
+#include <array>
+#include <cmath>
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
+#include <imgui.h>
+#include <optional>
+#include <string>
+#include <vector>
+#include <wx/string.h>
+
+namespace Slic3r::GUI {
+
+GLGizmoImage::GLGizmoImage(GLCanvas3D &parent, const std::string &icon_filename, unsigned int sprite_id)
+    : GLGizmoTextureDisplacement(parent, icon_filename, sprite_id)
+{
+}
+
+bool GLGizmoImage::on_init()
+{
+    if (!GLGizmoTextureDisplacement::on_init())
+        return false;
+    // Everything the base set up stays - it is the same painting machinery - except the key that
+    // opens it, which is this tool's own.
+    m_shortcut = Shortcut::GizmoImage;
+    return true;
+}
+
+std::string GLGizmoImage::on_get_name() const
+{
+    return _u8L("Image");
+}
+
+wxString GLGizmoImage::handle_snapshot_action_name(bool shift_down, GLGizmoPainterBase::Button button_down) const
+{
+    // Same paint, same masks; only the undo step's wording follows the tool the user is in.
+    const bool erasing = shift_down || (m_erase_mode != (button_down == GLGizmoPainterBase::Button::Right));
+    return erasing ? _L("Remove image from the area") : _L("Place image");
+}
+
+bool GLGizmoTextureDisplacement::pick_background_at(const Vec2d &mouse_pos)
+{
+    ModelVolume              *mv    = texture_volume();
+    ModelObject              *mo    = m_c->selection_info()->model_object();
+    TextureDisplacementLayer *layer = mv != nullptr ? active_layer() : nullptr;
+    if (mv == nullptr || mo == nullptr || layer == nullptr || layer->empty())
+        return false;
+
+    const int idx = texture_volume_raycaster_index();
+    if (idx < 0)
+        return false;
+    const Selection  &selection = m_parent.get_selection();
+    const Transform3d trafo = mo->instances[selection.get_instance_idx()]->get_transformation().get_matrix() * mv->get_matrix();
+    const Camera     &camera = wxGetApp().plater()->get_camera();
+
+    Vec3f hit = Vec3f::Zero(), normal = Vec3f::Zero();
+    if (!m_c->raycaster()->raycasters()[size_t(idx)]->unproject_on_mesh(
+            mouse_pos, trafo, camera, hit, normal,
+            m_c->object_clipper()->get_clipping_plane()))
+        return false;
+
+    // The picture's own colour at that point, read through the projection the bake uses, rather
+    // than the pixel on screen: the screen pixel carries the lighting and the filament the colour
+    // was already quantized to, so keying on it would remove the wrong thing.
+    //
+    // Uncorrected, deliberately. The key is applied at the end of the correction chain, against
+    // colours the earlier passes have already moved, so it has to be stated in those terms - the
+    // same reason the panel's dropper reads the corrected preview.
+    const indexed_triangle_set &base = mv->mesh().its;
+    const indexed_triangle_set  patch =
+        extract_painted_patch(base, mv->texture_displacement_facet(layer->slot).get_data());
+    Vec3f center = Vec3f::Zero(), axis = Vec3f::UnitZ(), average_normal = Vec3f::UnitZ();
+    if (!patch.indices.empty())
+        texture_displacement_patch_frame(patch, texture_displacement_vertex_normals(base), center, axis,
+                                         average_normal);
+
+    DecodedHeightTexture tex = decode_height_texture(*layer);
+    apply_color_adjustments(tex, *layer);
+    Vec3f rgb;
+    if (!sample_layer_color(tex, *layer, hit, normal, rgb, center, axis))
+        return false;
+
+    for (int c = 0; c < 3; ++c)
+        layer->bg_color[c] = std::clamp(rgb[c], 0.f, 1.f);
+    layer->bg_from_corners = false;
+    layer->bg_remove       = true;
+    m_image_bg_picking     = false;
+    m_preview_params_dirty = true;
+    m_parent.set_as_dirty();
+    return true;
+}
+
+void GLGizmoTextureDisplacement::set_file_drag_over(bool over)
+{
+    if (!image_mode() || m_file_drag_over == over)
+        return;
+    m_file_drag_over = over;
+    // A drag is not a mouse move as far as the canvas is concerned, so nothing would repaint and the
+    // zone would appear only once something else happened to trigger a frame.
+    m_parent.set_as_dirty();
+    m_parent.request_extra_frame();
+}
+
+// Drawn over the whole canvas on the foreground list, from inside the panel's ImGui frame, which is
+// what puts it above the 3D view and above the panel itself.
+void GLGizmoTextureDisplacement::render_image_drop_hint()
+{
+    if (!m_file_drag_over)
+        return;
+
+    const ImVec2 size = ImGui::GetIO().DisplaySize;
+    if (size.x < 1.f || size.y < 1.f)
+        return;
+    ImDrawList *dl   = ImGui::GetForegroundDrawList();
+    const ImU32 teal = ImGui::GetColorU32(ImGuiWrapper::COL_ORCA);
+
+    // Dim the view so the zone reads as a state the canvas is in, not as decoration on top of it.
+    dl->AddRectFilled(ImVec2(0.f, 0.f), size, IM_COL32(0, 0, 0, 70));
+
+    const float inset = std::round(ImGui::GetFontSize() * 1.2f);
+    const ImVec2 a(inset, inset), b(size.x - inset, size.y - inset);
+    if (b.x <= a.x || b.y <= a.y)
+        return;
+
+    // A dashed border, drawn as runs along the four edges: ImGui 1.83 has no dashed stroke.
+    const float dash = std::round(ImGui::GetFontSize() * 0.75f);
+    const float gap  = dash;
+    const float th   = std::max(2.f, std::round(ImGui::GetFontSize() * 0.12f));
+    for (float x = a.x; x < b.x; x += dash + gap) {
+        const float x1 = std::min(x + dash, b.x);
+        dl->AddLine(ImVec2(x, a.y), ImVec2(x1, a.y), teal, th);
+        dl->AddLine(ImVec2(x, b.y), ImVec2(x1, b.y), teal, th);
+    }
+    for (float y = a.y; y < b.y; y += dash + gap) {
+        const float y1 = std::min(y + dash, b.y);
+        dl->AddLine(ImVec2(a.x, y), ImVec2(a.x, y1), teal, th);
+        dl->AddLine(ImVec2(b.x, y), ImVec2(b.x, y1), teal, th);
+    }
+
+    // What dropping here will do. Worded as an invitation rather than a promise: anything that is
+    // not a picture falls through to the model loader, exactly as it did before this tool existed.
+    const std::string text = _u8L("Drop a picture to put it on the model");
+    const ImVec2      ts   = ImGui::CalcTextSize(text.c_str());
+    const float       pad  = std::round(ImGui::GetFontSize() * 0.8f);
+    const ImVec2      c((a.x + b.x) * 0.5f, (a.y + b.y) * 0.5f);
+    const ImVec2      r0(c.x - ts.x * 0.5f - pad, c.y - ts.y * 0.5f - pad * 0.6f);
+    const ImVec2      r1(c.x + ts.x * 0.5f + pad, c.y + ts.y * 0.5f + pad * 0.6f);
+    dl->AddRectFilled(r0, r1, ImGui::GetColorU32(ImGuiCol_WindowBg, 0.92f), ImGui::GetStyle().FrameRounding);
+    dl->AddRect(r0, r1, teal, ImGui::GetStyle().FrameRounding, 0, th * 0.5f);
+    dl->AddText(ImVec2(c.x - ts.x * 0.5f, c.y - ts.y * 0.5f), ImGui::GetColorU32(ImGuiCol_Text), text.c_str());
+}
+
+bool GLGizmoTextureDisplacement::drop_image_file(const std::string &path)
+{
+    if (!image_mode() || texture_volume() == nullptr)
+        return false;
+
+    // Imported rather than just read: the same thing the panel's Import tile does, so a dropped
+    // picture lands in "My images" and is there the next time without hunting for the file again.
+    std::string                              error;
+    const std::optional<TextureLibraryEntry> entry = import_texture_to_library(path, error);
+    if (!entry) {
+        show_error(nullptr, error);
+        return false;
+    }
+
+    // The tool starts with no layer at all, so a drop before anything is loaded has to make one.
+    if (active_layer() == nullptr)
+        add_texture_layer();
+    TextureDisplacementLayer *layer = active_layer();
+    if (layer == nullptr)
+        return false;
+    set_layer_texture(*layer, *entry);
+    m_parent.set_as_dirty();
+    return true;
+}
+
+// ---------------------------------------------------------------------------------------------
+// The Image tool's window.
+//
+// A member of GLGizmoTextureDisplacement rather than of GLGizmoImage, and defined here rather than
+// in that class's own file: it needs the same private machinery the displacement panel uses (the
+// layer, the texture picker, the previews, the bake), and keeping it here leaves that 1700 line
+// panel untouched instead of threading it with tests for which tool is drawing.
+//
+// What it deliberately leaves out, all of which only means something once the surface moves or once
+// there is more than one picture: brushes and the erase toggle, the layer stack, blend modes, depth,
+// midlevel, edge fade, tiling mode, the unwrap projection and its UV editor, seams, the wireframe
+// and the mesh-preparation sections.
+// ---------------------------------------------------------------------------------------------
+void GLGizmoTextureDisplacement::render_image_input_window(float x, float y, float bottom_limit)
+{
+    ModelObject *mo = m_c->selection_info()->model_object();
+    if (mo == nullptr)
+        return;
+    ModelVolume *mv = texture_volume();
+
+    // The palette follows project state nobody tells this gizmo about (the filaments in the
+    // sidebar), so it is checked once a frame and a change re-runs the preview.
+    cached_palette();
+    if (m_palette_changed)
+        m_preview_params_dirty = true;
+
+    // Everything this tool fixes, re-pinned each frame so what the preview shows is what Apply will
+    // produce: Standard's recipe, zero depth with colour on, a click that floods the connected
+    // surface rather than a brush, and the fast preview, which with no relief to build is both
+    // instant and exactly the final colour.
+    // Two statements, not one `||`: short-circuiting would skip the image presets on any frame the
+    // standard ones changed something.
+    const bool std_changed   = apply_standard_mode_presets(mv);
+    const bool image_changed = apply_image_mode_presets(mv);
+    if (std_changed || image_changed)
+        m_preview_params_dirty = true;
+    m_tool_type   = ToolType::SMART_FILL;
+    m_cursor_type = TriangleSelector::CursorType::POINTER;
+    m_erase_mode  = false;
+    m_auto_update = true;
+    if (!m_use_shaded_preview)
+        apply_view_mode(1);
+
+    float scale = m_parent.get_scale();
+#ifdef WIN32
+    const int dpi = get_dpi_for_window(wxGetApp().GetTopWindow());
+    scale *= (float) dpi / (float) DPI_DEFAULT;
+#endif // WIN32
+
+    const float approx_height = m_imgui->scaled(22.f);
+    y = std::min(y, bottom_limit - approx_height);
+
+    // Docked (the default) it is pinned to the right edge of the 3D canvas and cannot be moved, the
+    // same place and the same rule as the displacement panel, so the two tools do not put their
+    // controls in different corners. Undocked it becomes an ordinary floating window with a title
+    // bar to drag it by; the position is deliberately not seeded on undock, so it stays exactly
+    // where it was and the user simply gains the ability to move it.
+    ImGuiWindowFlags flags = ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoCollapse;
+    if (!m_undocked) {
+        flags |= ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoTitleBar;
+        // Right-aligned (pivot 1), so the width the window auto-resized to last frame does not need
+        // to be known here.
+        float right = float(m_parent.get_canvas_size().get_width()) - m_imgui->scaled(0.5f);
+        GizmoImguiSetNextWIndowPos(right, y, 0.f, 0.f, ImGuiCond_Always, 1.0f, 0.0f);
+    }
+
+    ImGuiWrapper::push_toolbar_style(m_parent.get_scale());
+    GizmoImguiBegin(get_name(), flags);
+    ensure_panel_icons();
+    const float previous_body_h   = m_panel_body_h;
+    const float previous_footer_h = m_panel_footer_h;
+
+    const ImGuiStyle &style    = ImGui::GetStyle();
+    const bool        busy     = m_bake_in_progress || m_prepare_in_progress;
+    const float       panel_w  = m_imgui->scaled(16.f);
+    const float       frame_h  = ImGui::GetFrameHeight();
+    const float       icon_sm  = std::round(frame_h * 1.05f);
+    const float       gap_s    = std::round(m_imgui->scaled(0.4f));
+    const float       label_w  = m_imgui->scaled(4.6f);
+    const float       wrap_w   = m_imgui->scaled(15.f);
+    const ImVec4      orca     = ImGuiWrapper::COL_ORCA;
+    const ImVec4      col_frame = ImGui::GetStyleColorVec4(ImGuiCol_Separator);
+
+    const auto hover_tip = [&](const auto &text) {
+        if (ImGui::IsItemHovered())
+            m_imgui->tooltip(text, wrap_w);
+    };
+    // Label column plus a slider filling the rest of the row, the same shape the displacement panel
+    // uses, so the two tools read as one family.
+    const auto float_row = [&](const char *id, const wxString &label, float *v, float v_min, float v_max,
+                               const char *format, bool log) -> bool {
+        const float x0 = ImGui::GetCursorPosX();
+        ImGui::AlignTextToFramePadding();
+        m_imgui->text(label);
+        ImGui::SameLine();
+        ImGui::SetCursorPosX(std::max(ImGui::GetCursorPosX(), x0 + label_w));
+        ImGui::SetNextItemWidth(x0 + panel_w - ImGui::GetCursorPosX());
+        return ImGui::SliderFloat(id, v, v_min, v_max, format,
+                                  ImGuiSliderFlags_AlwaysClamp | (log ? ImGuiSliderFlags_Logarithmic : 0));
+    };
+    // Borderless icon button, for the dock toggle: always the grey monochrome variant.
+    const auto icon_button = [&](int uid, const std::string &iconfile, const wxString &label,
+                                 const wxString &tip_text) -> bool {
+        const auto  it  = m_panel_icon_map.find(iconfile);
+        const float pad = std::max(1.f, std::round(icon_sm * 0.14f));
+        bool        clicked = false;
+        ImGui::PushID(uid);
+        ImGui::PushStyleVar(ImGuiStyleVar_FrameBorderSize, 0.f);
+        ImGui::PushStyleColor(ImGuiCol_Button, ImVec4(0.f, 0.f, 0.f, 0.f));
+        if (it != m_panel_icon_map.end() && !it->second.empty() && it->second[0]->is_valid()) {
+            const IconManager::Icon &ic = *it->second[0];
+            clicked = m_imgui->image_button((ImTextureID) (intptr_t) ic.tex_id,
+                                            ImVec2(icon_sm - 2.f * pad, icon_sm - 2.f * pad), ic.tl, ic.br, int(pad));
+        } else {
+            clicked = ImGui::Button(label.ToUTF8().data(), ImVec2(0.f, icon_sm));
+        }
+        ImGui::PopStyleColor();
+        ImGui::PopStyleVar();
+        ImGui::PopID();
+        hover_tip(tip_text);
+        return clicked;
+    };
+    // A section header that folds its contents away. ImGui's own CollapsingHeader draws a filled bar
+    // that is louder than anything else in this window, so this is the same triangle-and-text the
+    // displacement panel's "More settings" link uses, at heading weight.
+    const auto section = [&](const char *id, const wxString &label, bool &open) {
+        const float  arrow = std::round(ImGui::GetFontSize() * 0.55f);
+        const ImVec2 ts    = ImGui::CalcTextSize(label.ToUTF8().data());
+        const ImVec2 p     = ImGui::GetCursorScreenPos();
+        ImGui::PushID(id);
+        if (ImGui::InvisibleButton("##sec", ImVec2(panel_w, ts.y + gap_s)))
+            open = !open;
+        const bool  hot = ImGui::IsItemHovered();
+        ImDrawList *dl  = ImGui::GetWindowDrawList();
+        const ImU32 col = ImGui::GetColorU32(hot ? ImGuiCol_Text : ImGuiCol_TextDisabled);
+        const float cx = p.x + 0.5f * arrow, cy = p.y + 0.5f * ts.y, hs = 0.32f * arrow;
+        if (open)
+            dl->AddTriangleFilled(ImVec2(cx - hs, cy - 0.5f * hs), ImVec2(cx + hs, cy - 0.5f * hs),
+                                  ImVec2(cx, cy + 0.5f * hs), col);
+        else
+            dl->AddTriangleFilled(ImVec2(cx - 0.5f * hs, cy - hs), ImVec2(cx - 0.5f * hs, cy + hs),
+                                  ImVec2(cx + 0.5f * hs, cy), col);
+        dl->AddText(ImVec2(p.x + arrow + gap_s, p.y), col, label.ToUTF8().data());
+        ImGui::PopID();
+        return open;
+    };
+
+    // The integer twin of float_row, for the colour count.
+    const auto int_row = [&](const char *id, const wxString &label, int *v, int v_min, int v_max,
+                             const char *format) -> bool {
+        const float x0 = ImGui::GetCursorPosX();
+        ImGui::AlignTextToFramePadding();
+        m_imgui->text(label);
+        ImGui::SameLine();
+        ImGui::SetCursorPosX(std::max(ImGui::GetCursorPosX(), x0 + label_w));
+        ImGui::SetNextItemWidth(x0 + panel_w - ImGui::GetCursorPosX());
+        return ImGui::SliderInt(id, v, v_min, v_max, format, ImGuiSliderFlags_AlwaysClamp);
+    };
+    // Framed icon toggle, the displacement panel's one cut down to what this window needs.
+    const auto icon_toggle = [&](int uid, const std::string &iconfile, bool active, const wxString &label,
+                                 const wxString &tip_text) -> bool {
+        const auto  it   = m_panel_icon_map.find(iconfile);
+        const float pad  = std::max(1.f, std::round(icon_sm * 0.14f));
+        bool        clicked = false;
+        ImGui::PushID(uid);
+        ImGui::PushStyleVar(ImGuiStyleVar_FrameBorderSize, 0.f);
+        ImGui::PushStyleColor(ImGuiCol_Button, active ? ImVec4(orca.x, orca.y, orca.z, 0.22f) : ImVec4(0.f, 0.f, 0.f, 0.f));
+        if (it != m_panel_icon_map.end() && int(it->second.size()) > (active ? 1 : 0) &&
+            it->second[active ? 1 : 0]->is_valid()) {
+            const IconManager::Icon &ic = *it->second[active ? 1 : 0];
+            clicked = m_imgui->image_button((ImTextureID) (intptr_t) ic.tex_id,
+                                            ImVec2(icon_sm - 2.f * pad, icon_sm - 2.f * pad), ic.tl, ic.br, int(pad));
+        } else {
+            clicked = ImGui::Button(label.ToUTF8().data(), ImVec2(0.f, icon_sm));
+        }
+        ImGui::GetWindowDrawList()->AddRect(ImGui::GetItemRectMin(), ImGui::GetItemRectMax(),
+                                            ImGui::GetColorU32(active ? orca : col_frame), style.FrameRounding);
+        ImGui::PopStyleColor();
+        ImGui::PopStyleVar();
+        ImGui::PopID();
+        hover_tip(tip_text);
+        return clicked;
+    };
+
+    TextureDisplacementLayer *layer = mv != nullptr ? active_layer() : nullptr;
+
+    {
+        const float x0 = ImGui::GetCursorPosX();
+        ImGui::AlignTextToFramePadding();
+        m_imgui->push_bold_font();
+        m_imgui->text(wxString::FromUTF8(get_name(false)));
+        m_imgui->pop_bold_font();
+        ImGui::SameLine();
+        ImGui::SetCursorPosX(std::max(ImGui::GetCursorPosX(), x0 + panel_w - icon_sm));
+        if (icon_button(920, "canvas_drag.svg", m_undocked ? _L("Dock panel") : _L("Undock panel"),
+                        _L("Detach this panel so it can be dragged anywhere over the 3D view, or dock it back "
+                           "against the right edge.")))
+            m_undocked = !m_undocked;
+    }
+    ImGui::Separator();
+
+    // Everything between the title and the footer scrolls as one, so Apply and Close stay on screen
+    // on a short canvas instead of being the first thing pushed off the bottom. Sized from last
+    // frame's content and footer heights, as the displacement panel's body is.
+    const float bottom     = m_undocked ? ImGui::GetIO().DisplaySize.y : bottom_limit;
+    const float max_body_h = std::max(m_imgui->scaled(8.f), bottom - ImGui::GetCursorScreenPos().y -
+                                                                m_panel_footer_h - style.WindowPadding.y -
+                                                                style.ItemSpacing.y);
+    const float body_h      = m_panel_body_h > 0.f ? std::min(m_panel_body_h + 1.f, max_body_h) : max_body_h;
+    const float scrollbar_w = m_imgui->scaled(0.5f);
+    const ImVec4 grab       = wxGetApp().dark_mode() ? ImVec4(1.f, 1.f, 1.f, 0.26f) : ImVec4(0.f, 0.f, 0.f, 0.26f);
+    ImGui::PushStyleVar(ImGuiStyleVar_ScrollbarSize, scrollbar_w);
+    ImGui::PushStyleVar(ImGuiStyleVar_ScrollbarRounding, 0.5f * scrollbar_w);
+    ImGui::PushStyleColor(ImGuiCol_ScrollbarBg, ImVec4(0.f, 0.f, 0.f, 0.f));
+    ImGui::PushStyleColor(ImGuiCol_ScrollbarGrab, grab);
+    ImGui::PushStyleColor(ImGuiCol_ScrollbarGrabHovered, ImVec4(grab.x, grab.y, grab.z, 0.45f));
+    ImGui::PushStyleColor(ImGuiCol_ScrollbarGrabActive, ImVec4(grab.x, grab.y, grab.z, 0.65f));
+    ImGui::PushStyleColor(ImGuiCol_ChildBg, ImVec4(0.f, 0.f, 0.f, 0.f));
+    ImGui::BeginChild("##image_body", ImVec2(panel_w, body_h), false);
+
+    // The picture, shown whole and the full width of the window: it is the thing being placed, so a
+    // row-sized thumbnail beside a file name is the wrong size for it. Clicking it opens the library,
+    // which is also where Import lives, and before anything is loaded the same box is an empty frame
+    // with a plus in it - one target, in the same place, whichever state the tool is in.
+    const auto open_library = [&](int slot) {
+        m_picker_slot         = slot;
+        m_picker_open_request = true;
+    };
+    // A layer with no picture on it is the starting state, not a broken one: the tool creates the
+    // layer empty and the panel stays on the frame below until a picture has been chosen.
+    const bool has_picture = layer != nullptr && !layer->empty();
+    const bool placed      = mv != nullptr && mv->is_texture_displacement_painted();
+
+    // The handle comes up by itself the first moment there is something to anchor it to, so the
+    // picture can be nudged straight after the click that placed it without hunting for a toggle.
+    // Armed once: turning it back off has to stay off, not be undone on the next frame.
+    if (has_picture && placed && !m_image_handle_armed) {
+        m_image_handle_armed = true;
+        if (update_adjust_anchor())
+            m_adjust_texture_mode = true;
+    }
+    if (!has_picture) {
+        const float  box_h = std::round(panel_w * 0.6f);
+        const ImVec2 p0    = ImGui::GetCursorScreenPos();
+        m_imgui->disabled_begin(busy || mv == nullptr);
+        const bool clicked = ImGui::InvisibleButton("##load", ImVec2(panel_w, box_h));
+        m_imgui->disabled_end();
+        const bool  hot = ImGui::IsItemHovered();
+        ImDrawList *dl  = ImGui::GetWindowDrawList();
+        const ImU32 col = ImGui::GetColorU32(hot ? orca : col_frame);
+        dl->AddRect(p0, ImVec2(p0.x + panel_w, p0.y + box_h), col, style.FrameRounding);
+        const float cx = p0.x + 0.5f * panel_w, cy = p0.y + 0.5f * box_h;
+        const float arm = std::round(box_h * 0.18f), thick = std::max(1.f, std::round(box_h * 0.035f));
+        dl->AddLine(ImVec2(cx - arm, cy), ImVec2(cx + arm, cy), col, thick);
+        dl->AddLine(ImVec2(cx, cy - arm), ImVec2(cx, cy + arm), col, thick);
+        hover_tip(_u8L("Choose a picture to put on the model."));
+        if (clicked) {
+            if (layer == nullptr)
+                add_texture_layer();           // created with no picture on it, on purpose
+            open_library(layer != nullptr ? layer->slot : m_active_layer_slot);
+        }
+        ImGui::PushTextWrapPos(ImGui::GetCursorPosX() + panel_w);
+        ImGui::TextDisabled("%s", _u8L("Choose a picture, then click the model to put it there.").c_str());
+        ImGui::PopTextWrapPos();
+    } else {
+        // The colour texture is the corrected image at full resolution, which is exactly what should
+        // be previewed - move a correction slider and the box follows. A grayscale picture has no
+        // colour texture, so it falls back to the height thumbnail.
+        GLTexture  *shown  = get_layer_color_texture(*layer);
+        if (shown == nullptr)
+            shown = get_layer_thumbnail(*layer);
+        const float aspect = std::max(0.05f, layer_texture_aspect(*layer));
+        const float box_h  = std::clamp(std::round(panel_w / aspect), std::round(panel_w * 0.35f),
+                                        std::round(panel_w * 1.1f));
+        const ImVec2 box_min = ImGui::GetCursorScreenPos();
+        bool         box_hit = false;
+        if (shown != nullptr) {
+            box_hit = ImGui::ImageButton((ImTextureID) (intptr_t) shown->get_id(), ImVec2(panel_w, box_h),
+                                         ImVec2(0.f, 0.f), ImVec2(1.f, 1.f), 0);
+        } else {
+            box_hit = ImGui::Button("?##thumb", ImVec2(panel_w, box_h));
+        }
+        hover_tip(m_image_bg_picking ?
+                      _u8L("Click the background, here or on the model.") :
+                      _u8L("Choose a different picture. Where you placed it and how it is corrected stay as "
+                           "they are."));
+        if (box_hit) {
+            if (!m_image_bg_picking) {
+                open_library(layer->slot);
+            } else {
+                // Read straight out of the decoded image rather than off the screen: the preview is
+                // scaled, and it already has the corrections applied, so a screen read would key the
+                // corrected colour against itself.
+                const ImVec2 rel((ImGui::GetIO().MousePos.x - box_min.x) / panel_w,
+                                 (ImGui::GetIO().MousePos.y - box_min.y) / box_h);
+                const DecodedHeightTexture &tex = decode_height_texture(*layer);
+                if (tex.has_color()) {
+                    const int px = std::clamp(int(rel.x * float(tex.width)), 0, tex.width - 1);
+                    const int py = std::clamp(int(rel.y * float(tex.height)), 0, tex.height - 1);
+                    const size_t i = (size_t(py) * size_t(tex.width) + size_t(px)) * 3;
+                    for (int c = 0; c < 3; ++c)
+                        layer->bg_color[c] = float(tex.rgb[i + size_t(c)]) / 255.f;
+                    layer->bg_from_corners = false;
+                    layer->bg_remove       = true;
+                    m_preview_params_dirty = true;
+                }
+                m_image_bg_picking = false;
+            }
+        }
+        const std::string name = layer->name.empty() ? _u8L("Image") : layer->name;
+        ImGui::PushTextWrapPos(ImGui::GetCursorPosX() + panel_w);
+        ImGui::TextDisabled("%s", name.c_str());
+        ImGui::PopTextWrapPos();
+
+        if (!height_texture_has_color(*layer)) {
+            ImGui::PushTextWrapPos(ImGui::GetCursorPosX() + panel_w);
+            m_imgui->warning_text(_L("This image is grayscale, so it has no colors to print. Choose a color picture."));
+            ImGui::PopTextWrapPos();
+        }
+
+        // Placing it: one click floods the surface it lands on, out to the first fold sharper than
+        // the angle below. No brush, no erase toggle - on a flat side or a cube face the click alone
+        // is the whole gesture, and the slider is there for the cases where it is not.
+        ImGui::PushTextWrapPos(ImGui::GetCursorPosX() + panel_w);
+        ImGui::TextDisabled("%s", placed ? _u8L("Click the model to move the picture somewhere else.").c_str() :
+                                           _u8L("Click the model to put the picture there.").c_str());
+        ImGui::PopTextWrapPos();
+        float fill_angle = m_smart_fill_angle;
+        if (float_row("##fill_angle", _L("Spread"), &fill_angle, SmartFillAngleMin, SmartFillAngleMax, "%.0f°", false))
+            m_smart_fill_angle = fill_angle;
+        hover_tip(_u8L("How far a click spreads from the spot you hit: it keeps going while the surface stays "
+                       "flatter than this, and stops at a sharper fold. Small values keep it to one face."));
+
+        ImGui::Separator();
+        if (section("place", _L("Placement"), m_image_sec_place)) {
+
+        // Projection, minus Unwrap: that one is an editor's worth of UI (seams, islands, the UV pane)
+        // for a tool whose whole point is a click and a few sliders.
+        {
+            struct Mapping { const char *file; wxString label; wxString tip; TextureProjectionMethod method; };
+            const Mapping mappings[] = {
+                { "menu_obj_cube.svg", _L("Flat"),
+                  _L("Flat - lays the picture straight onto the surface from whichever axis it faces, and blends "
+                     "where it wraps around an edge. The right choice for a face or a flat side."),
+                  TextureProjectionMethod::Triplanar },
+                { "menu_obj_cylinder.svg", _L("Around"),
+                  _L("Around - wraps the picture around the area, for a round part like a mug or a tube."),
+                  TextureProjectionMethod::Cylindrical },
+                { "menu_obj_sphere.svg", _L("Ball"),
+                  _L("Ball - wraps the picture around the area in both directions, for a dome or a sphere."),
+                  TextureProjectionMethod::Spherical },
+                { "texture_displacement_map_view.svg", _L("From view"),
+                  _L("From view - throws the picture onto the area from where you are looking now, like a slide "
+                     "projector. Line the view up with the surface first, because faces turned away stretch."),
+                  TextureProjectionMethod::ViewProjected },
+            };
+            const float x0 = ImGui::GetCursorPosX();
+            ImGui::AlignTextToFramePadding();
+            // Plain text, like every other label in this window: the displacement panel greys its
+            // headings because it has many, and here there are five rows in total.
+            m_imgui->text(_L_CONTEXT("Mapping", "Texture Displacement"));
+            ImGui::SameLine();
+            ImGui::SetCursorPosX(std::max(ImGui::GetCursorPosX(), x0 + label_w));
+            for (int mi = 0; mi < int(IM_ARRAYSIZE(mappings)); ++mi) {
+                if (mi > 0)
+                    ImGui::SameLine(0.f, gap_s);
+                const bool on = layer->projection_method == mappings[mi].method;
+                if (icon_toggle(900 + mi, mappings[mi].file, on, mappings[mi].label, mappings[mi].tip) && !on) {
+                    // Capture the current view the moment "From view" is chosen, so it does something
+                    // sensible immediately rather than projecting from a stale direction.
+                    if (mappings[mi].method == TextureProjectionMethod::ViewProjected)
+                        capture_view_projection(*layer);
+                    layer->projection_method = mappings[mi].method;
+                    m_preview_params_dirty   = true;
+                }
+            }
+        }
+        if (layer->projection_method == TextureProjectionMethod::ViewProjected) {
+            if (m_imgui->button(_u8L("Capture current view"))) {
+                capture_view_projection(*layer);
+                m_preview_params_dirty = true;
+            }
+            hover_tip(_u8L("Throws the picture on again from where you are looking now. Orbit the model, press "
+                           "this, and it is re-laid from the new angle."));
+        }
+
+        m_preview_params_dirty |= float_row("##size", _L("Size"), &layer->tiling_scale, 1.f, 300.f, "%.1f mm", true);
+        hover_tip(_u8L("How wide the picture is on the model, in millimetres."));
+        m_preview_params_dirty |= float_row("##rotation", _L("Rotation"), &layer->rotation_deg, 0.f, 360.f, "%.0f°", false);
+        hover_tip(_u8L("Turns the picture on the surface, for lining it up with an edge of the model."));
+
+        // Sliding it into place, and whether it repeats. Both belong on one row: the handle is the
+        // coarse control and Tile decides what it is sliding - one copy, or a pattern.
+        {
+            const float x0 = ImGui::GetCursorPosX();
+            ImGui::AlignTextToFramePadding();
+            m_imgui->text(_L("Move"));
+            ImGui::SameLine();
+            ImGui::SetCursorPosX(std::max(ImGui::GetCursorPosX(), x0 + label_w));
+            if (icon_toggle(910, "texture_displacement_adjust.svg", m_adjust_texture_mode, _L("Move on the model"),
+                            _L("Move on the model - drag the handle that appears on the surface to slide the "
+                               "picture around, or one of its two arrows to slide it along just that axis."))) {
+                if (!m_adjust_texture_mode) {
+                    update_model_object(); // flush any pending placement before anchoring to it
+                    if (update_adjust_anchor())
+                        m_adjust_texture_mode = true;
+                    else
+                        show_error(nullptr, _u8L("Click the model to put the picture somewhere first."));
+                } else {
+                    m_adjust_texture_mode = false;
+                    m_adjust_drag_handle  = AdjustHandle::None;
+                }
+            }
+            ImGui::SameLine(0.f, gap_s * 2.f);
+            if (m_imgui->bbl_checkbox(_L("Tile"), layer->tile_enabled))
+                m_preview_params_dirty = true;
+            hover_tip(_u8L("Repeats the picture over the area instead of placing a single copy. Off by "
+                           "default, because a photo or a logo goes on once; Size then sets how big that "
+                           "one copy is."));
+        }
+
+        // The one number that decides how sharp the printed picture is. Each triangle prints in a
+        // single filament, so the mesh under the paint has to be finer than the detail wanted out of
+        // the image - and the budget above is what stops that running away.
+        {
+            TextureDisplacementOptions &opts = mv->texture_displacement_options;
+            float                       edge = opts.v2_refine_mm;
+            m_imgui->disabled_begin(busy);
+            if (float_row("##resolution", _L("Detail"), &edge, 0.02f, 2.f, "%.2f mm", true)) {
+                opts.v2_refine_mm      = edge;
+                m_preview_params_dirty = true;
+            }
+            m_imgui->disabled_end();
+            hover_tip(_u8L("How fine the mesh is made under the picture, in millimetres. Each triangle prints "
+                           "in one filament, so this is how sharp an edge between two colors can come out. "
+                           "Smaller costs triangles fast: halving it needs four times as many."));
+
+            // Refining past the budget is not an error - the bake simplifies back down to it - but the
+            // result then carries less of the picture than this slider asks for, and without saying so
+            // the only sign is a print that came out softer than expected.
+            const size_t budget = size_t(std::max(0, opts.v2_max_triangles_k)) * 1000;
+            const size_t needed = estimated_refined_triangles(*mv, edge);
+            if (budget > 0 && needed > budget * 5 / 4) {
+                const auto count = [](size_t n) {
+                    return n >= 1000000 ? Slic3r::format("%1$.1f M", double(n) / 1000000.) :
+                                          Slic3r::format("%1% k", (n + 500) / 1000);
+                };
+                ImGui::PushTextWrapPos(ImGui::GetCursorPosX() + panel_w);
+                m_imgui->warning_text(Slic3r::format(_u8L("Needs about %1% triangles, budget %2% - it will be "
+                                                          "simplified back down and come out softer."),
+                                                     count(needed), count(budget)));
+                ImGui::PopTextWrapPos();
+            }
+        }
+
+        } // Placement
+
+        ImGui::Separator();
+        if (section("color", _L("Color"), m_image_sec_color)) {
+
+        // Colour correction. Every one of these changes which filament each area lands in, which is
+        // why they are here rather than left to whatever the file happened to contain: a photo that
+        // prints as mud usually only needs contrast.
+        m_preview_params_dirty |= float_row("##brightness", _L("Brightness"), &layer->brightness, -1.f, 1.f, "%.2f", false);
+        hover_tip(_u8L("Lightens or darkens the whole picture before it is matched to your filaments."));
+        m_preview_params_dirty |= float_row("##contrast", _L("Contrast"), &layer->contrast, -1.f, 1.f, "%.2f", false);
+        hover_tip(_u8L("Pushes light and dark apart. Raise it when a photo prints as mud; lower it when "
+                       "everything collapses into the lightest and darkest filament."));
+        m_preview_params_dirty |= float_row("##saturation", _L("Saturation"), &layer->saturation, 0.f, 2.f, "%.2f", false);
+        hover_tip(_u8L("How strong the colors are. At 0 the picture is gray, so it prints in your grays and "
+                       "blacks; raising it pushes each area towards a purer filament."));
+        m_preview_params_dirty |= float_row("##hue", _L("Hue"), &layer->hue, -180.f, 180.f, "%.0f°", false);
+        hover_tip(_u8L("Turns every color of the picture around the color wheel, without changing how light "
+                       "it is. Your filaments are a fixed, arbitrary set, so this is what lets the picture "
+                       "meet them: if you have orange loaded but no red, a small turn puts the reds on it."));
+        m_preview_params_dirty |= float_row("##gamma", _L("Gamma"), &layer->gamma, 0.2f, 5.f, "%.2f", true);
+        hover_tip(_u8L("Lifts or drops the midtones without touching the brightest and darkest parts. Use it "
+                       "when the middle of the picture is the part coming out wrong."));
+        m_preview_params_dirty |= float_row("##sharpen", _L("Sharpen"), &layer->sharpness, 0.f, 1.f, "%.2f", false);
+        hover_tip(_u8L("Crisps up the edges before the picture is matched to your filaments. Worth more here "
+                       "than in a photo: a soft edge between two colors quantizes into a ragged band of "
+                       "both, and sharpening first makes it land in one place."));
+
+        // How many colours the picture may use. 2 is a logo in two flat colours, 4 or 5 a poster,
+        // off a photograph. This is not the same as the displacement tool's "Mixed colors", which
+        // caps how many mixed filament slots a bake may create rather than what the picture uses.
+        {
+            int count = layer->color_count;
+            if (int_row("##colors", _L("Colors"), &count, 0, 12, count == 0 ? _u8L("Off").c_str() : "%d")) {
+                // 1 is not a picture, so the slider steps over it on the way out of Off.
+                layer->color_count     = count == 1 ? 2 : count;
+                m_preview_params_dirty = true;
+            }
+            hover_tip(_u8L("Reduces the picture to this many colors before your filaments are matched to "
+                           "it, so it prints in at most that many. The colors are the ones the picture is "
+                           "actually made of, not an even split of the range. Off leaves it alone."));
+        }
+
+        if (m_imgui->bbl_checkbox(_L("Negative"), layer->color_invert))
+            m_preview_params_dirty = true;
+        hover_tip(_u8L("Prints the picture inverted, light for dark and each color for its opposite."));
+
+        } // Color
+
+        ImGui::Separator();
+        if (!section("bg", _L("Background"), m_image_sec_bg)) {
+            // Folded away, but still worth saying whether it is doing anything.
+            ImGui::SameLine();
+            ImGui::TextDisabled("%s", layer->bg_remove ? _u8L("removed").c_str() : _u8L("kept").c_str());
+        } else {
+        if (m_imgui->bbl_checkbox(_L("Remove background"), layer->bg_remove))
+            m_preview_params_dirty = true;
+        hover_tip(_u8L("Leaves the background unprinted, so the object's own color shows through instead of "
+                       "a slab of white behind a logo. A picture that is already transparent needs none of "
+                       "this: those parts are left out either way."));
+        if (layer->bg_remove) {
+            // Which colour is being removed, shown rather than described: the swatch is also a
+            // picker, and the dropper beside it takes the colour from the preview above.
+            const float x0 = ImGui::GetCursorPosX();
+            ImGui::AlignTextToFramePadding();
+            m_imgui->text(_L("Color"));
+            ImGui::SameLine();
+            ImGui::SetCursorPosX(std::max(ImGui::GetCursorPosX(), x0 + label_w));
+            float shown_bg[3] = { layer->bg_color[0], layer->bg_color[1], layer->bg_color[2] };
+            if (layer->bg_from_corners) {
+                // Nothing has been picked, so show what the corners actually gave: the same median
+                // the bake will key on, not a placeholder white.
+                const DecodedHeightTexture &tex = decode_height_texture(*layer);
+                if (tex.has_color() && tex.width > 1 && tex.height > 1) {
+                    const size_t n = size_t(tex.width) * size_t(tex.height);
+                    const size_t corner[4] = { 0, size_t(tex.width) - 1,
+                                               (size_t(tex.height) - 1) * size_t(tex.width), n - 1 };
+                    for (int c = 0; c < 3; ++c) {
+                        std::array<float, 4> v{};
+                        for (int i = 0; i < 4; ++i)
+                            v[size_t(i)] = float(tex.rgb[corner[i] * 3 + size_t(c)]);
+                        std::sort(v.begin(), v.end());
+                        shown_bg[c] = 0.5f * (v[1] + v[2]) / 255.f;
+                    }
+                }
+            }
+            ImGui::SetNextItemWidth(x0 + panel_w - ImGui::GetCursorPosX() - icon_sm - gap_s);
+            if (ImGui::ColorEdit3("##bg_color", shown_bg,
+                                  ImGuiColorEditFlags_NoInputs | ImGuiColorEditFlags_NoLabel)) {
+                for (int c = 0; c < 3; ++c)
+                    layer->bg_color[c] = shown_bg[c];
+                layer->bg_from_corners = false;
+                m_preview_params_dirty = true;
+            }
+            hover_tip(layer->bg_from_corners ?
+                          _u8L("Taken from the four corners of the picture, which is right for a logo on a "
+                               "plain card. Click to choose a color yourself instead.") :
+                          _u8L("The color being removed. Click to change it."));
+            ImGui::SameLine(0.f, gap_s);
+                if (icon_toggle(930, "texture_displacement_pipette.svg", m_image_bg_picking, _L("Pick the color"),
+                            _L("Pick the color - then click the background, either in the preview above or on "
+                               "the model itself.")))
+                m_image_bg_picking = !m_image_bg_picking;
+            if (!layer->bg_from_corners) {
+                ImGui::SameLine(0.f, gap_s);
+                if (m_imgui->button(_u8L("Corners"))) {
+                    layer->bg_from_corners = true;
+                    m_preview_params_dirty = true;
+                }
+                hover_tip(_u8L("Back to taking the color from the picture's four corners."));
+            }
+
+            m_preview_params_dirty |= float_row("##bg_tol", _L("Tolerance"), &layer->bg_tolerance, 0.01f, 0.6f, "%.2f", false);
+            hover_tip(_u8L("How different from that color still counts as background. Raise it when a "
+                           "shadow or a gradient is left behind; lower it when it starts eating the picture."));
+        }
+
+        } // Background
+
+        // Outside both sections, because it clears the colour corrections and the background key
+        // alike, and a reset that lives inside one of them would look like it only reached that far.
+        ImGui::Separator();
+        if (m_imgui->button(_u8L("Reset all"))) {
+            layer->brightness      = 0.f;
+            layer->contrast        = 0.f;
+            layer->saturation      = 1.f;
+            layer->hue             = 0.f;
+            layer->gamma           = 1.f;
+            layer->sharpness       = 0.f;
+            layer->color_count     = 0;
+            layer->bg_remove       = false;
+            layer->bg_tolerance    = 0.15f;
+            layer->bg_from_corners = true;
+            layer->bg_color[0] = layer->bg_color[1] = layer->bg_color[2] = 1.f;
+            m_image_bg_picking     = false;
+            layer->color_invert    = false;
+            m_preview_params_dirty = true;
+        }
+        hover_tip(_u8L("Puts every correction and the background back to where they started, leaving the "
+                       "picture as it was loaded. Where you placed it and how big it is are not touched."));
+    }
+
+    // The library popup lives in this window's scope, where its open request and the popup itself
+    // share one ID stack.
+    {
+        const ImVec2 win_min = ImGui::GetWindowPos();
+        const ImVec2 win_sz  = ImGui::GetWindowSize();
+        render_texture_library_popup(win_min, ImVec2(win_min.x + win_sz.x, win_min.y + win_sz.y));
+    }
+
+    // ImGui sliders report "changed" on every frame of a drag, and a preview rebuild is real work,
+    // so with the mouse still down it waits for the release.
+    if (m_preview_params_dirty && !ImGui::IsMouseDown(ImGuiMouseButton_Left)) {
+        rebuild_preview();
+        m_preview_params_dirty = false;
+    }
+
+    m_panel_body_h = ImGui::GetCursorPosY() - style.ItemSpacing.y;
+    ImGui::EndChild();
+    ImGui::PopStyleColor(5);
+    ImGui::PopStyleVar(2);
+
+    const float footer_top = ImGui::GetCursorScreenPos().y;
+    ImGui::Separator();
+    {
+        const bool painted   = placed;
+        const bool no_colors = mv != nullptr && !any_layer_colors(*mv);
+        // Colour is the only thing this bake produces, so with a grayscale picture there would be
+        // nothing to show for it - and it is not a cheap no-op: the bake still refines the painted
+        // area and replaces the mesh with the result.
+        const bool can_apply = !busy && mv != nullptr && painted && !no_colors;
+
+        const float button_h = std::round(frame_h * 1.25f);
+        const float button_w = std::max({ ImGui::CalcTextSize(_u8L("Apply").c_str()).x,
+                                          ImGui::CalcTextSize(_u8L("Close").c_str()).x,
+                                          ImGui::CalcTextSize(_u8L("Stop").c_str()).x,
+                                          ImGui::CalcTextSize(_u8L("Working...").c_str()).x }) +
+                               m_imgui->scaled(0.5f);
+        const float row_y  = ImGui::GetCursorPosY();
+        const float icon_h = 21.f * scale;
+        const float row_h  = std::max(icon_h, button_h);
+
+        ImGui::SetCursorPosY(row_y + (row_h - icon_h) * .5f);
+        ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(int(m_imgui->scaled(.5f)), style.ItemSpacing.y));
+        GLGizmoUtils::render_wiki_guide_button(m_parent, scale,
+                                               "https://www.orcaslicer.com/wiki/print_prepare/prepare_texture_displacement");
+        ImGui::PopStyleVar(1);
+
+        ImGui::SameLine(panel_w - button_w * 2 - style.ItemSpacing.x);
+        GLGizmoUtils::push_orca_button_style();
+        m_imgui->push_bold_font();
+        m_imgui->disabled_begin(!can_apply);
+        ImGui::SetCursorPosY(row_y + (row_h - button_h) * .5f);
+        const std::string apply_label = busy ? _u8L("Working...") : _u8L("Apply");
+        if (ImGui::Button((apply_label + "##apply").c_str(), ImVec2(button_w, button_h)))
+            bake_standard();
+        m_imgui->disabled_end();
+        m_imgui->pop_bold_font();
+        GLGizmoUtils::pop_orca_button_style();
+        if (ImGui::IsItemHovered(ImGuiHoveredFlags_AllowWhenDisabled))
+            m_imgui->tooltip(!has_picture ? _u8L("Choose a picture first.") :
+                             !painted     ? _u8L("Click the model to place the picture first.") :
+                             no_colors        ? _u8L("This picture is grayscale, so there is nothing to print. "
+                                                     "Choose a color picture.") :
+                                                _u8L("Prints the picture where you placed it, in the nearest of your "
+                                                     "loaded filaments. The surface itself is left exactly where it "
+                                                     "is: this adds color, not relief."),
+                             wrap_w);
+
+        ImGui::SameLine();
+        if (busy) {
+            if (ImGui::Button((_u8L("Stop") + "##stop").c_str(), ImVec2(button_w, button_h)))
+                wxGetApp().plater()->get_ui_job_worker().cancel_all();
+            hover_tip(_u8L("Stops it. Whatever it had already finished stays on the model, and can be undone."));
+        } else {
+            if (ImGui::Button((_u8L("Close") + "##close").c_str(), ImVec2(button_w, button_h)))
+                m_parent.reset_all_gizmos();
+            hover_tip(_u8L("Closes the tool. Your picture and where you put it stay with the model."));
+        }
+    }
+
+    m_panel_footer_h = ImGui::GetCursorScreenPos().y - footer_top;
+    // Both heights feed back into next frame's layout, so the window needs one more frame whenever
+    // either of them moved.
+    if (std::abs(m_panel_body_h - previous_body_h) > 0.5f || std::abs(m_panel_footer_h - previous_footer_h) > 0.5f)
+        m_parent.request_extra_frame();
+
+    // Last, on the foreground list, so it covers the panel as well as the view.
+    render_image_drop_hint();
+
+    GizmoImguiEnd();
+    ImGuiWrapper::pop_toolbar_style();
+}
+
+} // namespace Slic3r::GUI

src/slic3r/GUI/Gizmos/GLGizmoImage.hpp

@@ -0,0 +1,46 @@
+#ifndef slic3r_GLGizmoImage_hpp_
+#define slic3r_GLGizmoImage_hpp_
+
+#include "slic3r/GUI/Gizmos/GLGizmoTextureDisplacement.hpp"
+#include "slic3r/GUI/I18N.hpp"
+
+#include <string>
+#include <wx/string.h>
+
+namespace Slic3r::GUI {
+
+class GLCanvas3D;
+
+// "Put this picture on the model": the texture-displacement gizmo with the relief taken out of it.
+//
+// There is no second engine here and no copy of one. It is GLGizmoTextureDisplacement with
+// image_mode() on, which pins every layer to zero depth and colour on (see
+// apply_image_mode_presets()) and leaves out the controls that only mean something once the surface
+// moves. Painting, the layer stack, the texture library, the previews and the bake are the very same
+// code, reached the very same way - a zero-depth bake refines the painted area and writes the
+// colours exactly as a relief bake does, it just displaces by nothing.
+//
+// Its own toolbar button because the two are different jobs, not two settings of one: a user who
+// wants a photo on a part should not have to know what a height map is, or find the one slider that
+// has to be zero.
+class GLGizmoImage : public GLGizmoTextureDisplacement
+{
+public:
+    GLGizmoImage(GLCanvas3D &parent, const std::string &icon_filename, unsigned int sprite_id);
+
+protected:
+    bool image_mode() const override { return true; }
+
+    bool        on_init() override;
+    std::string on_get_name() const override;
+
+    wxString handle_snapshot_action_name(bool shift_down, Button button_down) const override;
+
+    std::string get_gizmo_entering_text() const override { return _u8L("Entering Image painting"); }
+    std::string get_gizmo_leaving_text() const override { return _u8L("Leaving Image painting"); }
+    std::string get_action_snapshot_name() const override { return _u8L("Image editing"); }
+};
+
+} // namespace Slic3r::GUI
+
+#endif // slic3r_GLGizmoImage_hpp_

src/slic3r/GUI/Gizmos/GLGizmoTextureDisplacement.cpp

@@ -409,10 +409,18 @@ std::unique_ptr<GLTexture> upload_color_texture(const DecodedHeightTexture &deco
                     for (int c = 0; c < 3; ++c)
                         sum[c] += decoded.rgb[si + size_t(c)];
                 }
+            // Coverage rides in the fourth channel, box-filtered with the colour, so the shader can
+            // leave the surface alone where the picture is not there (see the colour path in
+            // texture_displacement_shaded.fs).
+            unsigned int sum_a = 0;
+            if (decoded.has_alpha())
+                for (int sy = y0; sy < y1 && sy < decoded.height; ++sy)
+                    for (int sx = x0; sx < x1 && sx < decoded.width; ++sx)
+                        sum_a += decoded.alpha[size_t(sy) * size_t(decoded.width) + size_t(sx)];
             const size_t di = (size_t(y) * size_t(w) + size_t(x)) * 4;
             for (int c = 0; c < 3; ++c)
                 rgba[di + size_t(c)] = (n > 0) ? static_cast<unsigned char>(sum[size_t(c)] / n) : 0;
-            rgba[di + 3] = 255;
+            rgba[di + 3] = (decoded.has_alpha() && n > 0) ? static_cast<unsigned char>(sum_a / n) : 255;
         }
 
     auto texture = std::make_unique<GLTexture>();
@@ -494,17 +502,7 @@ bool GLGizmoTextureDisplacement::on_init()
         {ctrl + _L("Mouse wheel"), m_desc["gap_area"]},
         toggle_wireframe_shortcut
     };
-
-    // Both ways into the same input box on any slider in the panel: ImGui turns a slider into one when
-    // it is Ctrl+clicked or when it is given the keyboard focus, which is what the edit icon asks for.
-    m_desc["type_value"] = _L("Type an exact value into a slider");
-    m_shortcuts_sliders  = {
-        {ctrl + _L("Left mouse button"), m_desc["type_value"]},
-        {_L("Edit icon at a slider's right end"), m_desc["type_value"]},
-    };
-    for (std::vector<std::pair<wxString, wxString>> *list : {&m_shortcuts_brush, &m_shortcuts_bucket_fill, &m_shortcuts_gap_fill})
-        list->insert(list->end(), m_shortcuts_sliders.begin(), m_shortcuts_sliders.end());
-
+ 
     return true;
 }
 
@@ -541,6 +539,7 @@ void GLGizmoTextureDisplacement::on_shutdown()
     m_palette_pure_quantizer = nullptr;
     m_palette_filaments.clear();
     m_palette_images.clear();
+    m_palette_adjusts.clear();
     m_mix_ranking.reset();
     m_palette_slots.clear();
     m_palette_changed = false;
@@ -566,6 +565,8 @@ void GLGizmoTextureDisplacement::on_shutdown()
     m_seam_edit_mode      = false;
     m_adjust_drag_handle  = AdjustHandle::None;
     m_adjust_anchor_valid = false;
+    m_image_handle_armed  = false;
+    m_file_drag_over      = false;
     // The pane is request-only: closing the gizmo drops the request, so reopening it later doesn't
     // silently reopen the pane too.
     m_show_uv_editor = false;
@@ -770,8 +771,21 @@ bool GLGizmoTextureDisplacement::on_mouse(const wxMouseEvent &mouse_event)
 {
     if (m_seam_edit_mode)
         return on_mouse_seam(mouse_event);
-    if (m_adjust_texture_mode)
-        return on_mouse_adjust_texture(mouse_event);
+    // The background dropper takes the next click wherever it lands, the model included, so it comes
+    // before both the handle and the paint.
+    if (m_image_bg_picking && mouse_event.LeftDown() &&
+        pick_background_at(Vec2d(mouse_event.GetX(), mouse_event.GetY())))
+        return true;
+    if (m_adjust_texture_mode) {
+        if (on_mouse_adjust_texture(mouse_event))
+            return true;
+        // The displacement tool turns this mode on deliberately, so there a click off the handle
+        // doing nothing is the point. The Image tool has it on from the start, so the same click has
+        // to fall through and place the picture, or turning it on would disable the tool's one
+        // gesture.
+        if (!image_mode())
+            return false;
+    }
 
     const bool handled = GLGizmoPainterBase::on_mouse(mouse_event);
     // A consumed drag/click is a paint (or erase) event: the base class has already updated the live
@@ -1573,6 +1587,9 @@ void GLGizmoTextureDisplacement::render_shaded_preview_mesh()
     shader->set_uniform("height_tex", 0);
     shader->set_uniform("height_tex_texel", Vec2f(1.f / float(tex->get_width()), 1.f / float(tex->get_height())));
     shader->set_uniform("depth_mm", layer->depth_mm);
+    // Without this the preview wrapped the image and showed a repeating pattern where the bake
+    // places a single copy.
+    shader->set_uniform("tile_enabled", layer->tile_enabled);
     shader->set_uniform("tiling_scale", layer->tiling_scale);
     // Read off the uploaded texture rather than the decoded one: they are the same image, and this is
     // the aspect the sampler will actually see.
@@ -3596,6 +3613,11 @@ void GLGizmoTextureDisplacement::update_model_object()
         wxGetApp().obj_list()->update_info_items(std::find(mos.begin(), mos.end(), mo) - mos.begin());
         m_parent.post_event(SimpleEvent(EVT_GLCANVAS_SCHEDULE_BACKGROUND_PROCESS));
         rebuild_preview();
+        // The on-canvas handle is anchored to the paint patch, so a stroke that moved the paint has
+        // to move it with them. Matters most in the Image tool, where the handle is on from the
+        // start and a click moves the picture to a different part of the model.
+        if (m_adjust_texture_mode)
+            update_adjust_anchor();
     }
 }
 
@@ -3678,6 +3700,7 @@ void GLGizmoTextureDisplacement::ensure_panel_icons()
     // a monochrome ("normal", grey in the current theme) and an original-colour variant.
     static const std::vector<std::string> names = {
         "texture_displacement_brush.svg", "texture_displacement_face.svg", "texture_displacement_connected_area.svg",
+        "texture_displacement_pipette.svg", // the Image panel's background dropper
         "texture_displacement_real_preview.svg", "texture_displacement_fast_preview.svg",
         "texture_displacement_checker.svg", "texture_displacement_distortion.svg",
         "texture_displacement_wireframe.svg", "texture_displacement_cross.svg",
@@ -3690,7 +3713,6 @@ void GLGizmoTextureDisplacement::ensure_panel_icons()
         "texture_displacement_adjust.svg", "canvas_drag.svg", "texture_displacement_move_up.svg",
         "texture_displacement_move_down.svg", "texture_displacement_drag.svg",
         "texture_displacement_select_all.svg", "texture_displacement_erase_all.svg",
-        "edit.svg", // the "type a value" button at the right end of every slider
     };
     std::vector<std::string> paths;
     paths.reserve(names.size());
@@ -3737,13 +3759,24 @@ void GLGizmoTextureDisplacement::add_texture_layer()
     // Start the layer off on the first library texture rather than on nothing at all: a textureless
     // layer looks broken (painting on it appears to do nothing, because there is no height map to
     // displace by). The user swaps it for another from the layer's own picker.
-    const std::vector<TextureLibraryEntry> &library = texture_library();
-    if (!library.empty())
-        if (const LibraryTexture *tex = get_library_texture(library.front().path)) {
-            layer.name       = library.front().name;
-            layer.path       = library.front().path;
-            layer.image_data = tex->image_data;
-        }
+    //
+    // Not in the Image tool: there the layer deliberately starts with no picture at all, so the panel
+    // stays on its empty frame until the user has chosen one. Picking a shipped height map for them
+    // would be choosing the wrong thing twice over - it is not their picture, and most of that
+    // library is grayscale, which an image bake cannot print.
+    if (image_mode()) {
+        // One copy, not a repeating pattern: a photo or a logo is placed once. The panel's Tile
+        // checkbox is there for the cases that do want it, so this is a default and not a pin.
+        layer.tile_enabled = false;
+    } else {
+        const std::vector<TextureLibraryEntry> &library = texture_library();
+        if (!library.empty())
+            if (const LibraryTexture *tex = get_library_texture(library.front().path)) {
+                layer.name       = library.front().name;
+                layer.path       = library.front().path;
+                layer.image_data = tex->image_data;
+            }
+    }
     mv->texture_displacement_layers.push_back(std::move(layer));
     // A new layer opens with every setting showing; there is nothing on it yet to hide settings from.
     m_layer_expanded[size_t(free_slot)] = true;
@@ -3938,15 +3971,19 @@ void GLGizmoTextureDisplacement::render_texture_library_popup(const ImVec2 &pane
         return n;
     };
 
-    ImGui::TextDisabled("%s", _u8L("Built-in").c_str());
-    {
+    // The shipped library is grayscale height maps, which is what the displacement tool wants and the
+    // opposite of what an image bake can use: it prints colour, and a height map has none. So the
+    // Image tool offers only the user's own pictures, and the section is left out entirely rather
+    // than shown full of things that would all warn when picked.
+    if (!image_mode()) {
+        ImGui::TextDisabled("%s", _u8L("Built-in").c_str());
         const ImVec2 origin = ImGui::GetCursorScreenPos();
         const int    count  = grid(origin, false);
         end_grid(origin, count);
         if (count == 0)
             ImGui::TextDisabled("%s", _u8L("No textures found.").c_str());
     }
-    ImGui::TextDisabled("%s", _u8L("My textures").c_str());
+    ImGui::TextDisabled("%s", image_mode() ? _u8L("My images").c_str() : _u8L("My textures").c_str());
     {
         const ImVec2 origin = ImGui::GetCursorScreenPos();
         const int    count  = grid(origin, true);
@@ -3954,15 +3991,20 @@ void GLGizmoTextureDisplacement::render_texture_library_popup(const ImVec2 &pane
         if (ImGui::Button("+##import_texture", ImVec2(tile, tile)))
             import_clicked = true;
         if (ImGui::IsItemHovered())
-            m_imgui->tooltip(_u8L("Import your own image as a height map. It is converted to the format the slicer "
-                                  "bakes from and saved to your personal texture folder, kept separate from the "
-                                  "textures shipped with OrcaSlicer."),
+            m_imgui->tooltip(image_mode() ?
+                                 _u8L("Import a picture from your computer. Its colors are kept, and it is saved to "
+                                      "your personal folder so it is here next time.") :
+                                 _u8L("Import your own image as a height map. It is converted to the format the "
+                                      "slicer bakes from and saved to your personal texture folder, kept separate "
+                                      "from the textures shipped with OrcaSlicer."),
                              m_imgui->scaled(20.f));
         end_grid(origin, count + 1);
     }
 
     ImGui::PushTextWrapPos(ImGui::GetCursorPosX() + grid_w);
-    ImGui::TextDisabled("%s", _u8L("PNG, JPG or BMP - converted to a height map on import. Hover one of yours to remove it.").c_str());
+    ImGui::TextDisabled("%s", image_mode() ?
+                                  _u8L("PNG, JPG or BMP. Hover one to remove it.").c_str() :
+                                  _u8L("PNG, JPG or BMP - converted to a height map on import. Hover one of yours to remove it.").c_str());
     ImGui::PopTextWrapPos();
 
     if (chosen || import_clicked)
@@ -4542,15 +4584,22 @@ const std::vector<GLGizmoTextureDisplacement::PaletteEntry> &GLGizmoTextureDispl
     // The images themselves rather than their addresses, so a freed and reallocated image can never
     // pass for the old one. Whether one has colour, and whether its colours are flat, follows from it.
     std::vector<std::shared_ptr<std::vector<unsigned char>>> images;
+    // ... and what each one is corrected by, which changes the colours the mixes are ranked against
+    // without changing the image it came from.
+    std::vector<ColorAdjustKey> adjusts;
     if (mv != nullptr)
         for (const TextureDisplacementLayer &layer : mv->texture_displacement_layers)
-            if (layer.color_enabled && !layer.empty())
+            if (layer.color_enabled && !layer.empty()) {
                 images.push_back(layer.image_data);
+                adjusts.push_back(ColorAdjustKey::of(layer));
+            }
 
-    const bool ranking_stale = filaments != m_palette_filaments || images != m_palette_images;
+    const bool ranking_stale = filaments != m_palette_filaments || images != m_palette_images ||
+                               adjusts != m_palette_adjusts;
     if (ranking_stale) {
         m_palette_filaments = std::move(filaments);
         m_palette_images    = std::move(images);
+        m_palette_adjusts   = std::move(adjusts);
         m_mix_ranking.reset();
     }
     if (mixing && !m_mix_ranking)
@@ -4627,9 +4676,12 @@ std::vector<GLGizmoTextureDisplacement::MixTarget> GLGizmoTextureDisplacement::m
             continue;
         TextureDisplacementLayer raw = layer;
         raw.smoothing                = 0.f;
-        const DecodedHeightTexture tex = decode_height_texture(raw);
+        DecodedHeightTexture tex = decode_height_texture(raw);
         if (!tex.has_color())
             continue;
+        // Corrected first: the mixes are chosen to cover the colours the bake will actually ask for,
+        // and a darkened or desaturated image asks for different ones.
+        apply_color_adjustments(tex, layer);
 
         // 16 levels per channel, each bin keeping the mean of the colours that fell in it: a coarse grid
         // to gather on, without snapping every colour to a bin corner.
@@ -5335,10 +5387,16 @@ GLTexture *GLGizmoTextureDisplacement::get_layer_color_texture(const TextureDisp
 {
     if (layer.empty() || !layer.color_enabled)
         return nullptr;
-    if (m_color_tex && m_color_tex_source == layer.image_data.get() && m_color_tex_smoothing == layer.smoothing)
+    const ColorAdjustKey adjust = ColorAdjustKey::of(layer);
+    if (m_color_tex && m_color_tex_source == layer.image_data.get() && m_color_tex_smoothing == layer.smoothing &&
+        m_color_tex_adjust == adjust)
         return m_color_tex.get();
 
-    std::unique_ptr<GLTexture> texture = upload_color_texture(decode_height_texture(layer), HEIGHT_TEX_MAX_PX);
+    // Corrected here rather than inside the decode, exactly as prepare_sampleable_layers() does for
+    // the bake, so the fast preview shades the image the bake will print.
+    DecodedHeightTexture tex = decode_height_texture(layer);
+    apply_color_adjustments(tex, layer);
+    std::unique_ptr<GLTexture> texture = upload_color_texture(tex, HEIGHT_TEX_MAX_PX);
     if (!texture) {
         m_color_tex.reset();
         m_color_tex_source = nullptr;
@@ -5347,6 +5405,7 @@ GLTexture *GLGizmoTextureDisplacement::get_layer_color_texture(const TextureDisp
     m_color_tex           = std::move(texture);
     m_color_tex_source    = layer.image_data.get();
     m_color_tex_smoothing = layer.smoothing;
+    m_color_tex_adjust    = adjust;
     return m_color_tex.get();
 }
 
@@ -5423,6 +5482,8 @@ static constexpr float STD_SUBDIV_BORDER_MM   = 0.4f;
 // what the eye actually lands on - a stepped outline around a printed decal reads as a defect in a
 // way a slightly coarse relief transition does not - and it costs triangles along an outline only.
 static constexpr float STD_SUBDIV_COLOR_MM    = 0.25f;
+// The Image tool's triangle budget, in thousands. See apply_image_mode_presets().
+static constexpr int   IMAGE_BUDGET_K        = 1000;
 
 bool GLGizmoTextureDisplacement::apply_standard_mode_presets(ModelVolume *mv)
 {
@@ -5453,6 +5514,61 @@ bool GLGizmoTextureDisplacement::apply_standard_mode_presets(ModelVolume *mv)
     return changed;
 }
 
+// Pinned into the volume rather than applied on the way to the bake, exactly as Standard mode pins
+// displace_border and smooth_enabled above: the preview, the bake, the triangle estimate and the
+// palette all read the layers straight off the volume, and a value that only some of them saw would
+// put the preview and the bake out of step.
+//
+// The two tools share one layer stack - that is what "not a fork" means here - so opening the Image
+// tool on a volume whose layers carry relief flattens them, and they stay flat when the displacement
+// tool is reopened. Only that one number changes: the paint, the image, the placement and any relief
+// already baked into the mesh are untouched.
+bool GLGizmoTextureDisplacement::apply_image_mode_presets(ModelVolume *mv)
+{
+    if (mv == nullptr)
+        return false;
+    bool                        changed = false;
+    TextureDisplacementOptions &opts    = mv->texture_displacement_options;
+    // A million triangles for the picture. The auto budget is 750 k, chosen for relief, where the
+    // triangles buy shape; here they buy nothing but the sharpness of the edges between colours, and
+    // that is the whole output, so it is worth spending more of them on it.
+    if (opts.v2_max_triangles_k != IMAGE_BUDGET_K) {
+        opts.v2_max_triangles_k = IMAGE_BUDGET_K;
+        changed                 = true;
+    }
+    // Resolution is a slider in this panel rather than an Auto checkbox, so it needs a real value to
+    // start from: the same recommendation Auto would have produced for this model.
+    if (opts.v2_refine_mm <= 0.f) {
+        const float edge   = v2_recommendation(*mv).edge_mm;
+        opts.v2_refine_mm  = edge > 0.f ? edge : 0.3f;
+        changed            = true;
+    }
+    for (TextureDisplacementLayer &layer : mv->texture_displacement_layers) {
+        // Zero depth is the whole of "no relief": the bake still refines the painted area and still
+        // writes the colours, every layer just contributes a displacement of 0 (see
+        // make_combined_displacement_sampler()). Nothing special-cases it.
+        if (layer.depth_mm != 0.f) {
+            layer.depth_mm = 0.f;
+            changed        = true;
+        }
+        // Colour is the only thing an image bake produces, so it is on wherever there is colour to
+        // use rather than being a checkbox the user could leave off and wonder at.
+        const bool wanted = height_texture_has_color(layer);
+        if (layer.color_enabled != wanted) {
+            layer.color_enabled = wanted;
+            changed             = true;
+        }
+        // Unwrap is the one projection the Image tool does not offer: it is an editor's worth of UI
+        // (seams, islands, the UV pane) for a case that wants a click and a slider. A layer arriving
+        // from the displacement tool set to it falls back to the triplanar default.
+        if (layer.projection_method == TextureProjectionMethod::LSCM) {
+            layer.projection_method = TextureProjectionMethod::Triplanar;
+            changed                 = true;
+        }
+    }
+    return changed;
+}
+
 void GLGizmoTextureDisplacement::bake_standard()
 {
     ModelVolume *mv = texture_volume();
@@ -5761,6 +5877,14 @@ void GLGizmoTextureDisplacement::render_paint_cursor_hint()
 
 void GLGizmoTextureDisplacement::on_render_input_window(float x, float y, float bottom_limit)
 {
+    // The Image tool gets its own, much smaller window (see GLGizmoImage.cpp): everything below this
+    // point is the displacement panel, and it is left exactly as it was rather than being threaded
+    // with tests for which of the two tools is drawing.
+    if (image_mode()) {
+        render_image_input_window(x, y, bottom_limit);
+        return;
+    }
+
     ModelObject *mo = m_c->selection_info()->model_object();
     if (!mo)
         return;
@@ -5930,8 +6054,8 @@ void GLGizmoTextureDisplacement::on_render_input_window(float x, float y, float
         }
         return s + "...";
     };
-    // Label column + a slider filling the rest of the row, value printed inside the track.
-    // `right_inset` keeps a layer card's inner padding.
+    // Label column + a slider filling the rest of the row, value printed inside the track. Ctrl+click on
+    // any of these types a value in. `right_inset` keeps a layer card's inner padding.
     const auto slider_label = [&](const wxString &label) {
         const float x0 = ImGui::GetCursorPosX();
         ImGui::AlignTextToFramePadding();
@@ -5939,98 +6063,17 @@ void GLGizmoTextureDisplacement::on_render_input_window(float x, float y, float
         ImGui::SameLine();
         ImGui::SetCursorPosX(std::max(ImGui::GetCursorPosX(), x0 + label_w));
     };
-
-    // ---- Typed values on sliders ----
-    // Every slider in the panel goes through typed_row(), so all of them take a number the same two
-    // ways: Ctrl+click on the track, or the edit icon at the right end for the same box without the
-    // modifier. Both end up in ImGui's own "temp input" mode - the icon only asks ImGui to focus the
-    // slider, which is what turns it into an input box (see SliderScalar) - so the parsing, the
-    // clamping and the Enter/click-away behaviour are ImGui's, not a second implementation.
-
-    // Retires a click whose row is no longer being drawn - the panel changed mode in between - so that
-    // it cannot fire later when that row comes back. Before any row is drawn, so a live one still wins.
-    if (!m_slider_type_request.empty() && ImGui::GetFrameCount() > m_slider_type_request_frame + 1)
-        m_slider_type_request.clear();
-
-    // Exactly as tall as the slider it sits beside, so it lines up with the track without the row
-    // having to be re-centred around it; icon_button() pads the glyph itself down to about 0.7 of this.
-    const float edit_icon_w = frame_h;
-    // What the slider's own width has to give up for the icon beside it.
-    const float edit_icon_room = edit_icon_w + gap_s;
-
-    // One end of a range, through the slider's own format, so the bounds in the tooltip read exactly
-    // like the value in the track. A parenthesised note in the format - "(auto)" - is dropped: it
-    // describes the current state, not the bound.
-    const auto fmt_bound = [](const char *format, auto v) {
-        char buf[64];
-        std::snprintf(buf, sizeof(buf), format, v);
-        std::string out(buf);
-        const size_t paren = out.find('(');
-        if (paren != std::string::npos)
-            out.erase(paren);
-        while (!out.empty() && out.back() == ' ')
-            out.pop_back();
-        return out;
-    };
-    const auto edit_icon_tip = [](const std::string &lo, const std::string &hi) {
-        return _u8L("Type a value instead of dragging. Ctrl+click on the slider does the same.") + "\n\n" +
-               Slic3r::format(_u8L("Range: %1% to %2%"), lo, hi);
-    };
-
-    // Draws the edit icon at the right end of the row and then `slider` to its left - in that order on
-    // purpose. The slider is then the last item submitted, so the hover_tip() a caller writes after the
-    // row still describes the slider rather than the icon, and no row has to pass its tooltip through
-    // here. `item_w` follows SetNextItemWidth's convention (negative measures back from the right edge)
-    // and already has edit_icon_room taken out of it.
-    const auto typed_row = [&](const char *id, float item_w, const std::string &tip,
-                               const std::function<bool()> &slider) -> bool {
-        const float x0 = ImGui::GetCursorPosX();
-        const float w  = item_w > 0.f ? item_w : std::max(1.f, ImGui::GetContentRegionAvail().x + item_w);
-        ImGui::SetCursorPosX(x0 + w + gap_s);
-        if (icon_button(int(ImGui::GetID(id)), "edit.svg", edit_icon_w, _L("Edit"), from_u8(tip))) {
-            m_slider_type_request       = id;
-            m_slider_type_request_frame = ImGui::GetFrameCount();
-            m_parent.set_as_dirty(); // the next frame is where the request above is turned into focus
-        }
-        // Back onto the same row and to its start, which is where the slider belongs.
-        ImGui::SameLine(0.f, 0.f);
-        ImGui::SetCursorPosX(x0);
-        // Deferred from the click a frame ago: SetKeyboardFocusHere() is a request for the *next*
-        // frame, so it has to be issued before the slider it names, not from the icon beside it.
-        if (m_slider_type_request == id) {
-            ImGui::SetKeyboardFocusHere();
-            m_slider_type_request.clear();
-            m_parent.set_as_dirty(); // the focus only lands on a frame that actually gets drawn
-        }
-        ImGui::SetNextItemWidth(w);
-        return slider();
-    };
-
-    // The two forms every slider in the panel is one of. They derive the icon's range note from the
-    // bounds they are already given, so no row states its bounds or its format twice.
-    const auto typed_slider = [&](const char *id, float item_w, float *v, float v_min, float v_max,
-                                  const char *format, bool log) -> bool {
-        return typed_row(id, item_w, edit_icon_tip(fmt_bound(format, v_min), fmt_bound(format, v_max)), [&] {
-            return ImGui::SliderFloat(id, v, v_min, v_max, format,
-                                      ImGuiSliderFlags_AlwaysClamp | (log ? ImGuiSliderFlags_Logarithmic : 0));
-        });
-    };
-    const auto typed_slider_int = [&](const char *id, float item_w, int *v, int v_min, int v_max,
-                                      const char *format) -> bool {
-        return typed_row(id, item_w, edit_icon_tip(fmt_bound(format, v_min), fmt_bound(format, v_max)), [&] {
-            return ImGui::SliderInt(id, v, v_min, v_max, format, ImGuiSliderFlags_AlwaysClamp);
-        });
-    };
-
     const auto float_row = [&](const char *id, const wxString &label, float *v, float v_min, float v_max, const char *format,
                                bool log, float right_inset) -> bool {
         slider_label(label);
-        return typed_slider(id, -(std::max(right_inset, 1.f) + edit_icon_room), v, v_min, v_max, format, log);
+        ImGui::SetNextItemWidth(-std::max(right_inset, 1.f));
+        return ImGui::SliderFloat(id, v, v_min, v_max, format, ImGuiSliderFlags_AlwaysClamp | (log ? ImGuiSliderFlags_Logarithmic : 0));
     };
     const auto int_row = [&](const char *id, const wxString &label, int *v, int v_min, int v_max, const char *format,
                              float right_inset) -> bool {
         slider_label(label);
-        return typed_slider_int(id, -(std::max(right_inset, 1.f) + edit_icon_room), v, v_min, v_max, format);
+        ImGui::SetNextItemWidth(-std::max(right_inset, 1.f));
+        return ImGui::SliderInt(id, v, v_min, v_max, format, ImGuiSliderFlags_AlwaysClamp);
     };
     const auto layer_name = [](const TextureDisplacementLayer &l) {
         return l.name.empty() ? Slic3r::format(_u8L("Layer %1%"), l.slot + 1) : l.name;
@@ -6252,10 +6295,10 @@ void GLGizmoTextureDisplacement::on_render_input_window(float x, float y, float
         const auto  centre_on_row = [&](float h) { ImGui::SetCursorPosY(row_y + std::round((icon_md - h) * 0.5f)); };
         vsep(icon_md);
         if (is_brush_mode) {
+            ImGui::SetNextItemWidth(std::max(1.f, row_end - ImGui::GetCursorPosX() - (3.f * gap_s + 1.f + 2.f * icon_sm)));
             centre_on_row(frame_h);
-            typed_slider("##cursor_radius",
-                         std::max(1.f, row_end - ImGui::GetCursorPosX() - (3.f * gap_s + 1.f + 2.f * icon_sm) - edit_icon_room),
-                         &m_cursor_radius, CursorRadiusMin, CursorRadiusMax, "%.2f mm", false);
+            ImGui::SliderFloat("##cursor_radius", &m_cursor_radius, CursorRadiusMin, CursorRadiusMax, "%.2f mm",
+                               ImGuiSliderFlags_AlwaysClamp);
             hover_tip(m_desc.at("cursor_size"));
             vsep(icon_sm);
             const bool is_circle = m_cursor_type == TriangleSelector::CursorType::CIRCLE;
@@ -6269,9 +6312,10 @@ void GLGizmoTextureDisplacement::on_render_input_window(float x, float y, float
                             _L("Sphere - paints only within a ball around the point under the cursor")))
                 m_cursor_type = TriangleSelector::CursorType::SPHERE;
         } else if (is_area_mode) {
+            ImGui::SetNextItemWidth(std::max(1.f, row_end - ImGui::GetCursorPosX()));
             centre_on_row(frame_h);
-            typed_slider("##smart_fill_angle", std::max(1.f, row_end - ImGui::GetCursorPosX() - edit_icon_room),
-                         &m_smart_fill_angle, SmartFillAngleMin, SmartFillAngleMax, "%.0f°", false);
+            ImGui::SliderFloat("##smart_fill_angle", &m_smart_fill_angle, SmartFillAngleMin, SmartFillAngleMax, "%.0f°",
+                               ImGuiSliderFlags_AlwaysClamp);
             hover_tip(_u8L("Angle threshold - the fill stops at edges sharper than this"));
         } else {
             centre_on_row(frame_h);
@@ -7463,7 +7507,7 @@ void GLGizmoTextureDisplacement::on_render_input_window(float x, float y, float
             : m_tool_type == ToolType::SMART_FILL  ? m_shortcuts_bucket_fill 
             : m_tool_type == ToolType::BRUSH       ? m_shortcuts_brush 
             : m_tool_type == ToolType::GAP_FILL    ? m_shortcuts_gap_fill 
-            : m_shortcuts_sliders; // the sliders are there whether or not a painting tool is
+            : std::vector<std::pair<wxString, wxString>>{};
 
         ImGui::SetCursorPosY(row_y + (row_h - icon_h) * .5f); // center vertically
         ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(int(m_imgui->scaled(.5f)), style.ItemSpacing.y));

src/slic3r/GUI/Gizmos/GLGizmoTextureDisplacement.hpp

@@ -154,6 +154,33 @@ public:
     // What the cache was built from.
     std::vector<ColorRGBA>                                   m_palette_filaments;
     std::vector<std::shared_ptr<std::vector<unsigned char>>> m_palette_images; // the colouring layers' images
+    // One layer's colour correction, as a value that can be compared and cached on. It belongs to
+    // every cache keyed on "what the image looks like", because a correction slider changes the
+    // pixels while leaving the image_data pointer alone.
+    struct ColorAdjustKey
+    {
+        float brightness = 0.f, contrast = 0.f, saturation = 1.f, gamma = 1.f, hue = 0.f;
+        float sharpness = 0.f, bg_tolerance = 0.15f;
+        float bg_r = 1.f, bg_g = 1.f, bg_b = 1.f;
+        int   color_count = 0;
+        bool  invert = false, bg_remove = false, bg_from_corners = true;
+        bool  operator==(const ColorAdjustKey &o) const
+        {
+            return brightness == o.brightness && contrast == o.contrast && saturation == o.saturation &&
+                   gamma == o.gamma && hue == o.hue && sharpness == o.sharpness &&
+                   bg_tolerance == o.bg_tolerance && bg_r == o.bg_r && bg_g == o.bg_g && bg_b == o.bg_b &&
+                   color_count == o.color_count && invert == o.invert && bg_remove == o.bg_remove &&
+                   bg_from_corners == o.bg_from_corners;
+        }
+        bool operator!=(const ColorAdjustKey &o) const { return !(*this == o); }
+        static ColorAdjustKey of(const TextureDisplacementLayer &l)
+        {
+            return { l.brightness,  l.contrast,     l.saturation,      l.gamma,        l.hue,
+                     l.sharpness,   l.bg_tolerance, l.bg_color[0],     l.bg_color[1],  l.bg_color[2],
+                     l.color_count, l.color_invert, l.bg_remove,       l.bg_from_corners };
+        }
+    };
+    std::vector<ColorAdjustKey> m_palette_adjusts; // alongside m_palette_images, one per entry
     std::optional<std::vector<PaletteEntry>>                 m_mix_ranking;    // rank_mixes(), computed on demand
     bool                                                     m_palette_mixing     = false;
     int                                                      m_palette_mix_count  = 0;
@@ -203,7 +230,25 @@ public:
     // rotation handles instead of painting); otherwise forwards to the normal painting handling.
     bool on_mouse(const wxMouseEvent &mouse_event) override;
 
+    // Loads `path` as the Image tool's picture, importing it into the user's library on the way so
+    // it is there next time. For a drop onto the 3D view; see PlaterDropTarget::OnDropFiles(). False
+    // when this is not the Image tool, or the file could not be read.
+    bool drop_image_file(const std::string &path);
+
+    // Called while a file is being dragged over the 3D view, so the Image tool can show that
+    // dropping it there will do something. Without it the drag has no feedback at all and the only
+    // way to find out is to let go.
+    void set_file_drag_over(bool over);
+
 protected:
+    // True in the Image tool (see GLGizmoImage): this same gizmo restricted to the one case where
+    // the surface does not move at all - a colour picture laid on the model. Everything behind the
+    // panel is shared and unchanged: the same layers, the same paint masks, the same bake. This flag
+    // only tells the panel which of the two tools it is drawing, and makes it pin the values the
+    // restricted case fixes (see apply_image_mode_presets()).
+    virtual bool image_mode() const { return false; }
+
+    bool        on_init() override;
     void        on_render_input_window(float x, float y, float bottom_limit) override;
     std::string on_get_name() const override;
     // Never in the assemble view: its toolbar does not offer this gizmo, and every preview here is drawn
@@ -221,8 +266,11 @@ protected:
     EnforcerBlockerType get_left_button_state_type() const override { return m_erase_mode ? EnforcerBlockerType::NONE : EnforcerBlockerType::ENFORCER; }
     EnforcerBlockerType get_right_button_state_type() const override { return m_erase_mode ? EnforcerBlockerType::ENFORCER : EnforcerBlockerType::NONE; }
 
+    // Paint / Erase, from the panel. See get_left_button_state_type(). Protected because a subclass
+    // overriding handle_snapshot_action_name() has to read the same flag to name the undo step.
+    bool m_erase_mode = false;
+
 private:
-    bool on_init() override;
     void update_model_object() override;
     void update_from_model_object(bool first_update) override;
     void on_opening() override {}
@@ -268,6 +316,36 @@ private:
     // the paint if it were not carried across (see prepare_mesh()).
     void bake_standard();
 
+    // Image mode's fixed values, on top of Standard's and pinned the same way (every frame, so the
+    // preview cannot disagree with the bake): zero depth on every layer, and colour on wherever the
+    // picture has any. Those two are what turn the displacement bake into "put this picture on the
+    // model" without a second code path. Returns true if it actually changed something.
+    bool apply_image_mode_presets(ModelVolume *mv);
+    // The Image tool's whole window: load a picture, click the model to place it, correct it, Apply.
+    // Defined in GLGizmoImage.cpp, beside the class it exists for, rather than here - it is a member
+    // only so that it can reach the same private machinery the displacement panel uses, and keeping
+    // it out of this file leaves that panel's 1700 lines alone.
+    void render_image_input_window(float x, float y, float bottom_limit);
+    // Set once the Image tool has switched its placement handle on for the current picture, so that
+    // turning the handle back off stays off instead of being re-armed on the next frame.
+    bool m_image_handle_armed = false;
+    // Set between a drag entering the 3D view and leaving or dropping on it; drives the drop zone
+    // render_image_input_window() draws over the canvas.
+    bool m_file_drag_over = false;
+    void render_image_drop_hint();
+    // Set while the panel's background dropper is armed: the next click on the picture preview takes
+    // the colour under it instead of opening the library.
+    bool m_image_bg_picking = false;
+    // Takes the background colour from the point of the model under `mouse_pos`: the picture's own
+    // colour there, read through the same projection the bake uses, not the lit pixel on screen.
+    // False when the ray misses or the layer does not colour that point, leaving the dropper armed.
+    bool pick_background_at(const Vec2d &mouse_pos);
+    // Which of the Image panel's sections are unfolded. Panel state for the session, deliberately
+    // not saved with the project.
+    bool m_image_sec_place = true;
+    bool m_image_sec_color = true;
+    bool m_image_sec_bg    = true;
+
     // Queues one prepare_mesh() run on the job worker and commits its result when it lands. Every
     // mesh-preparation button goes through here - Pro's Remesh, Pro's adaptive Subdivide and Standard's
     // Bake differ only in which stages `params` enables and in what happens afterwards:
@@ -399,8 +477,6 @@ private:
     void set_layer_texture(TextureDisplacementLayer &layer, const TextureLibraryEntry &entry);
     void import_custom_texture(TextureDisplacementLayer &layer);
 
-    // Paint / Erase, from the panel. See get_left_button_state_type().
-    bool m_erase_mode = false;
     // Per slot: whether the layer's card shows every setting or only Depth, Tile size and Rotation.
     // Panel state only, not saved with the project.
     std::array<bool, TEXTURE_DISPLACEMENT_MAX_LAYERS> m_layer_expanded{};
@@ -934,6 +1010,7 @@ private:
     std::unique_ptr<GLTexture> m_color_tex;
     const void                *m_color_tex_source    = nullptr;
     float                      m_color_tex_smoothing = -1.f;
+    ColorAdjustKey m_color_tex_adjust;
 
     // Library textures the picker has shown at least once, keyed by file path (see LibraryTexture).
     std::map<std::string, LibraryTexture> m_library_textures;
@@ -1016,15 +1093,6 @@ private:
     std::vector<std::pair<wxString, wxString>> m_shortcuts_bucket_fill;
     // Contains all shortcuts in the format of {shortcut, description}, e.g. {alt + _L("Left mouse button"), _L("Part_selection")}
     std::vector<std::pair<wxString, wxString>> m_shortcuts_gap_fill;
-    // The two ways every slider in the panel takes a typed value. They hold whatever tool is selected,
-    // so they are tacked onto each of the lists above and stand on their own when no tool is active.
-    std::vector<std::pair<wxString, wxString>> m_shortcuts_sliders;
-    // The slider whose edit icon was just clicked, as its ImGui id, and the frame it was clicked on.
-    // The row acts on it on the next frame - ImGui's keyboard-focus request only takes effect a frame
-    // later - and clears it; the frame number is what retires a request whose row has gone off screen
-    // in the meantime. Panel state only, not saved with the project.
-    std::string m_slider_type_request;
-    int         m_slider_type_request_frame = 0;
 
     // Icons for the panel's icon buttons (tools, views, mapping, tiling, layer actions). Loaded through IconManager with
     // the same colour/monochrome variants the main toolbar uses, so an inactive button shows the icon in

src/slic3r/GUI/Gizmos/GLGizmosManager.cpp

@@ -22,6 +22,7 @@
 //#include "slic3r/GUI/Gizmos/GLGizmoHollow.hpp"
 #include "slic3r/GUI/Gizmos/GLGizmoSeam.hpp"
 #include "slic3r/GUI/Gizmos/GLGizmoMmuSegmentation.hpp"
+#include "slic3r/GUI/Gizmos/GLGizmoImage.hpp"
 #include "slic3r/GUI/Gizmos/GLGizmoTextureDisplacement.hpp"
 #include "slic3r/GUI/Gizmos/GLGizmoSimplify.hpp"
 #include "slic3r/GUI/Gizmos/GLGizmoEmboss.hpp"
@@ -201,6 +202,11 @@ void GLGizmosManager::switch_gizmos_icon_filename()
             // light/dark switch.
             gizmo->set_icon_filename("toolbar_texture_displacement.svg");
             break;
+        case(EType::Image):
+            // Drawn flat in Orca's menu-icon palette, which reads on either background, so one file
+            // serves both themes here too.
+            gizmo->set_icon_filename("toolbar_image.svg");
+            break;
         case(EType::MeshBoolean):
             gizmo->set_icon_filename(m_is_dark ? "toolbar_meshboolean_dark.svg" : "toolbar_meshboolean.svg");
             break;
@@ -252,6 +258,8 @@ bool GLGizmosManager::init()
     m_gizmos.emplace_back(new GLGizmoMmuSegmentation(m_parent, m_is_dark ? "mmu_segmentation_dark.svg" : "mmu_segmentation.svg", EType::MmSegmentation));
     // One shared icon (no dedicated dark variant yet); it recolours acceptably in both themes.
     m_gizmos.emplace_back(new GLGizmoTextureDisplacement(m_parent, "toolbar_texture_displacement.svg", EType::TextureDisplacement));
+    // The same gizmo restricted to the zero-displacement case; see GLGizmoImage.
+    m_gizmos.emplace_back(new GLGizmoImage(m_parent, "toolbar_image.svg", EType::Image));
     m_gizmos.emplace_back(new GLGizmoEmboss(m_parent, m_is_dark ? "toolbar_text_dark.svg" : "toolbar_text.svg", EType::Emboss));
     m_gizmos.emplace_back(new GLGizmoSVG(m_parent));
     m_gizmos.emplace_back(new GLGizmoMeasure(m_parent, m_is_dark ? "toolbar_measure_dark.svg" : "toolbar_measure.svg", EType::Measure));
@@ -585,6 +593,8 @@ bool GLGizmosManager::gizmo_event(SLAGizmoEventType action, const Vec2d& mouse_p
         return dynamic_cast<GLGizmoFuzzySkin*>(m_gizmos[FuzzySkin].get())->gizmo_event(action, mouse_position, shift_down, alt_down, control_down);
     else if (m_current == TextureDisplacement)
         return dynamic_cast<GLGizmoTextureDisplacement*>(m_gizmos[TextureDisplacement].get())->gizmo_event(action, mouse_position, shift_down, alt_down, control_down);
+    else if (m_current == Image)
+        return dynamic_cast<GLGizmoImage*>(m_gizmos[Image].get())->gizmo_event(action, mouse_position, shift_down, alt_down, control_down);
     else if (m_current == MeshBoolean)
         return dynamic_cast<GLGizmoMeshBoolean*>(m_gizmos[MeshBoolean].get())->gizmo_event(action, mouse_position, shift_down, alt_down, control_down);
     else if (m_current == BrimEars)
@@ -599,6 +609,7 @@ bool GLGizmosManager::is_paint_gizmo()
            m_current == EType::MmSegmentation ||
            m_current == EType::FuzzySkin ||
            m_current == EType::TextureDisplacement ||
+           m_current == EType::Image ||
            m_current == EType::Seam;
 }
 
@@ -1550,6 +1561,8 @@ std::string get_name_from_gizmo_etype(GLGizmosManager::EType type)
         return "Fuzzy Skin Painting";
     case GLGizmosManager::EType::TextureDisplacement:
         return "Texture Displacement";
+    case GLGizmosManager::EType::Image:
+        return "Image";
     default:
         return "";
     }

src/slic3r/GUI/Gizmos/GLGizmosManager.hpp

@@ -96,6 +96,7 @@ public:
         FuzzySkin,
         MmSegmentation,
         TextureDisplacement,
+        Image,
         Emboss,
         Svg,
         Measure,

src/slic3r/GUI/Plater.cpp

@@ -67,6 +67,7 @@
 #include "slic3r/GUI/Field.hpp"
 #include "slic3r/GUI/Widgets/PopupWindow.hpp"
 #include <set>
+#include <wx/filename.h>
 #include "slic3r/GUI/Widgets/StaticLine.hpp"
 #include "slic3r/GUI/GUI_ObjectSettings.hpp"
 #include "slic3r/GUI/ColorDecomposeDialog.hpp"
@@ -246,6 +247,7 @@
 #include "DeviceCore/DevNozzleSystem.h"          // DevNozzle, GetExtNozzles / GetRackNozzles
 #include "ProjectDirtyStateManager.hpp"
 #include "Gizmos/GLGizmoSimplify.hpp" // create suggestion notification
+#include "Gizmos/GLGizmoImage.hpp" // Drop an image onto the Image tool
 #include "Gizmos/GLGizmoSVG.hpp" // Drop SVG file
 #include "Gizmos/GizmoObjectManipulation.hpp"
 
@@ -7110,6 +7112,9 @@ void Sidebar::can_search()
     p->can_search();
 }
 
+// Defined with the other drop helpers below; forward declared because the drop target uses it.
+void set_image_drag_over(Plater &plater, bool over);
+
 class PlaterDropTarget : public wxFileDropTarget
 {
 public:
@@ -7119,12 +7124,53 @@ public:
 
     virtual bool OnDropFiles(wxCoord x, wxCoord y, const wxArrayString &filenames);
 
+    // A drag has no feedback of its own, so the Image tool is told when one is over the view and
+    // draws a drop zone for as long as it is. wxWidgets cannot hand us the file names before the
+    // drop on GTK, so this says nothing about what is being dragged: the zone invites a picture,
+    // and anything else still falls through to the model loader.
+    virtual wxDragResult OnEnter(wxCoord x, wxCoord y, wxDragResult def)
+    {
+        set_image_drag_over(m_plater, true);
+        return wxFileDropTarget::OnEnter(x, y, def);
+    }
+    virtual void OnLeave()
+    {
+        set_image_drag_over(m_plater, false);
+        wxFileDropTarget::OnLeave();
+    }
+
 private:
     MainFrame& m_mainframe;
     Plater& m_plater;
 };
 
 namespace {
+// The Image gizmo, but only while it is the open one. Null otherwise, which is what keeps a drag or
+// a drop from meaning anything different with the tool closed.
+GLGizmoImage *open_image_gizmo(Plater &plater)
+{
+    GLCanvas3D *canvas = plater.canvas3D();
+    if (canvas == nullptr)
+        return nullptr;
+    GLGizmosManager &gizmos = canvas->get_gizmos_manager();
+    if (gizmos.get_current_type() != GLGizmosManager::Image)
+        return nullptr;
+    return dynamic_cast<GLGizmoImage *>(gizmos.get_gizmo(GLGizmosManager::Image));
+}
+
+// True when `file` is a picture and the Image gizmo is the one currently open, in which case it has
+// taken the file. Mirrors emboss_svg() below, which does the same for an SVG and the text tool.
+bool drop_image_on_gizmo(Plater &plater, const wxString &file)
+{
+    static const std::set<wxString> image_ext = { "png", "jpg", "jpeg", "bmp" };
+    const wxString                  ext       = wxFileName(file).GetExt().Lower();
+    if (image_ext.count(ext) == 0)
+        return false;
+
+    GLGizmoImage *image = open_image_gizmo(plater);
+    return image != nullptr && image->drop_image_file(into_u8(file));
+}
+
 bool emboss_svg(Plater& plater, const wxString &svg_file, const Vec2d& mouse_drop_position)
 {
     std::string svg_file_str = into_u8(svg_file);
@@ -7783,6 +7829,12 @@ const std::regex Plater::priv::pattern_zip_amf(".*[.]zip[.]amf", std::regex::ica
 const std::regex Plater::priv::pattern_any_amf(".*[.](amf|amf[.]xml|zip[.]amf)", std::regex::icase);
 const std::regex Plater::priv::pattern_prusa(".*bbl", std::regex::icase);
 
+void set_image_drag_over(Plater &plater, bool over)
+{
+    if (GLGizmoImage *image = open_image_gizmo(plater))
+        image->set_file_drag_over(over);
+}
+
 bool PlaterDropTarget::OnDropFiles(wxCoord x, wxCoord y, const wxArrayString &filenames)
 {
 #ifdef WIN32
@@ -7790,11 +7842,18 @@ bool PlaterDropTarget::OnDropFiles(wxCoord x, wxCoord y, const wxArrayString &fi
     this->MSWUpdateDragImageOnLeave();
 #endif // WIN32
 
+    set_image_drag_over(m_plater, false); // the drag is over, whoever ends up taking the file
+
     m_mainframe.Raise();
     m_mainframe.select_tab(TAB_ID_PREPARE);
     if (wxGetApp().is_editor())
         m_plater.select_view_3D("3D");
 
+    // A picture dropped while the Image tool is open is that tool's input, not a model to load. Only
+    // then: with the tool closed a dropped PNG goes on doing whatever it did before.
+    if (filenames.size() == 1 && drop_image_on_gizmo(m_plater, filenames.Last()))
+        return true;
+
     // When only one .svg file is dropped on scene
     if (filenames.size() == 1) {
         const wxString &filename = filenames.Last();

src/slic3r/GUI/Shortcuts.cpp

@@ -114,6 +114,9 @@ constexpr std::array<ShortcutInfo, size_t(Shortcut::Count)> shortcut_table = {{
     SHORTCUT(GizmoAssembly,     "gizmo_assembly",     L("Gizmo assemble"),                                       PLATER, { 'Y' }),
     SHORTCUT(GizmoBrimEars,     "gizmo_brim_ears",    L("Gizmo brim ears"),                                      PLATER, { 'E' }),
     SHORTCUT(GizmoDisplacement, "gizmo_displacement", L("Gizmo texture displacement painting"),                  PLATER, { 'D' }),
+    // Unbound by default: every single letter this context can reach is already taken, and a default
+    // that shadows one of them is worse than none. The shortcuts dialog lists it for binding.
+    SHORTCUT(GizmoImage,        "gizmo_image",        L("Gizmo image painting"),                                 PLATER, KeyChord{}),
 
     // Sliders
     SHORTCUT(GoToLayer,           "go_to_layer",           L("Jump to layer"),                                   PREVIEW, { 'G', SHIFT }),

src/slic3r/GUI/Shortcuts.hpp

@@ -38,7 +38,7 @@ enum class Shortcut : uint8_t {
     MoveSelectionLeft, MoveSelectionRight, MoveSelectionUp, MoveSelectionDown, RotateSelectionLeft, RotateSelectionRight,
     // Gizmos
     GizmoMove, GizmoRotate, GizmoScale, GizmoFlatten, GizmoCut, GizmoMeshBoolean, GizmoFdmSupports, GizmoSeam, GizmoFuzzySkin,
-    GizmoMmuSegmentation, GizmoEmboss, GizmoMeasure, GizmoAssembly, GizmoBrimEars, GizmoDisplacement,
+    GizmoMmuSegmentation, GizmoEmboss, GizmoMeasure, GizmoAssembly, GizmoBrimEars, GizmoDisplacement, GizmoImage,
     // Sliders
     GoToLayer, LayerSliderUp, LayerSliderDown, MovesSliderLeft, MovesSliderRight, MovesSliderStart, MovesSliderEnd,
     // Painting tools