Keep mixed-color filaments intact when the extruder count changes (#15385)

* Keep mixed-color filaments intact when the extruder count changes

The extruder-count spinner resized the filament arrays in bulk at the tail,
which is where mixed-color slots live, so a new filament landed behind the
mix and the sidebar skipped a slot number. It now adds and removes one slot
at a time through the same calls the sidebar's +/- buttons use, so a new
slot opens ahead of the mixed tail and a removal renumbers object filament
ids, painted facets, custom g-code and mixed components rather than
clamping them away.

Drops the vector overload of set_num_filaments(), which this leaves without
callers.

src/libslic3r/PresetBundle.cpp

@@ -3190,63 +3190,6 @@ void PresetBundle::export_selections(AppConfig &config)
     BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << boost::format(": printer %1%, print %2%, filaments[0] %3% ")%printers.get_selected_preset_name() % prints.get_selected_preset_name() %filament_presets[0];
 }
 
-// BBS
-void PresetBundle::set_num_filaments(unsigned int n, std::vector<std::string> new_colors) {
-    int old_filament_count = this->filament_presets.size();
-    if (n > old_filament_count && old_filament_count != 0)
-        filament_presets.resize(n, filament_presets.back());
-    else {
-        filament_presets.resize(n);
-    }
-    ConfigOptionStrings* filament_color = project_config.option<ConfigOptionStrings>("filament_colour");
-    ConfigOptionStrings *filament_multi_color = project_config.option<ConfigOptionStrings>("filament_multi_colour");
-    ConfigOptionStrings* filament_color_type = project_config.option<ConfigOptionStrings>("filament_colour_type");
-    ConfigOptionInts* filament_map = project_config.option<ConfigOptionInts>("filament_map");
-    ConfigOptionInts* filament_nozzle_map = project_config.option<ConfigOptionInts>("filament_nozzle_map");
-    ConfigOptionInts* filament_volume_map = project_config.option<ConfigOptionInts>("filament_volume_map");
-
-    filament_color->resize(n);
-    // Sync filament multi colour
-    filament_multi_color->values.resize(n);
-    for (size_t i = 0; i < n; i++) {
-        filament_multi_color->values[i] = filament_color->values[i];
-    }
-    filament_color_type->resize(n);
-    filament_map->values.resize(n, 1);
-    filament_nozzle_map->values.resize(n, 0);
-    filament_volume_map->values.resize(n, static_cast<int>(NozzleVolumeType::nvtStandard));
-    ams_multi_color_filment.resize(n);
-
-    // Mixed-color metadata is a parallel per-filament array set, so it has to grow and shrink
-    // with the filament count exactly like filament_colour above.
-    if (auto* opt = project_config.option<ConfigOptionBools>("filament_is_mixed"))
-        opt->values.resize(n, false);
-    if (auto* opt = project_config.option<ConfigOptionStrings>("filament_mixed_components"))
-        opt->values.resize(n, std::string{});
-    if (auto* opt = project_config.option<ConfigOptionStrings>("filament_mixed_sublayer_ratios"))
-        opt->values.resize(n, std::string{});
-    if (auto* opt = project_config.option<ConfigOptionBools>("filament_mixed_gradient"))
-        opt->values.resize(n, false);
-    if (auto* opt = project_config.option<ConfigOptionStrings>("filament_mixed_gradient_range"))
-        opt->values.resize(n, std::string{});
-    if (auto* opt = project_config.option<ConfigOptionStrings>("filament_mixed_gradient_curve"))
-        opt->values.resize(n, std::string{});
-    if (auto* opt = project_config.option<ConfigOptionBools>("filament_mixed_gradient_per_part"))
-        opt->values.resize(n, false);
-
-    // BBS set new filament color to new_color
-    if (old_filament_count < n) {
-        if (!new_colors.empty()) {
-            for (int i = old_filament_count; i < n; i++) {
-                filament_color->values[i] = new_colors[i - old_filament_count];
-                filament_multi_color->values[i] = new_colors[i - old_filament_count];
-                filament_color_type->values[i]  = "1";  // default color type
-            }
-        }
-    }
-
-    update_multi_material_filament_presets();
-}
 void PresetBundle::set_num_filaments(unsigned int n, std::string new_color)
 {
     unsigned old_filament_count = this->filament_presets.size();
@@ -3262,6 +3205,11 @@ void PresetBundle::set_num_filaments(unsigned int n, std::string new_color)
     ConfigOptionInts* filament_nozzle_map = project_config.option<ConfigOptionInts>("filament_nozzle_map");
     ConfigOptionInts* filament_volume_map = project_config.option<ConfigOptionInts>("filament_volume_map");
 
+    // Which slots are new is a fact about the arrays below, not about filament_presets:
+    // update_multi_material_filament_presets() tops that list up to the nozzle count on its own,
+    // so it can already sit at the new size while every array below is still at the old one.
+    const size_t old_slot_count = filament_color->values.size();
+
     filament_color->resize(n);
     // Sync filament multi colour
     filament_multi_color->values.resize(n);
@@ -3292,13 +3240,11 @@ void PresetBundle::set_num_filaments(unsigned int n, std::string new_color)
         opt->values.resize(n, false);
 
     //BBS set new filament color to new_color
-    if (old_filament_count < n) {
-        if (!new_color.empty()) {
-            for (unsigned i = old_filament_count; i < n; i++) {
-                filament_color->values[i] = new_color;
-                filament_multi_color->values[i] = new_color;
-                filament_color_type->values[i]  = "1";  // default color type
-            }
+    if (!new_color.empty()) {
+        for (size_t i = old_slot_count; i < n; i++) {
+            filament_color->values[i] = new_color;
+            filament_multi_color->values[i] = new_color;
+            filament_color_type->values[i]  = "1";  // default color type
         }
     }
 
@@ -3407,6 +3353,16 @@ size_t PresetBundle::num_mixed_filaments() const
     return opt == nullptr ? 0 : size_t(std::count(opt->values.begin(), opt->values.end(), true));
 }
 
+// Counted off the mixed flags, not filament_presets: that list is topped up to the nozzle count on
+// its own, so it can sit a slot ahead of the arrays that describe slots. Unlike the sibling
+// physical_filament_config_indices(), which bounds by filament_presets, this ignores that top-up.
+size_t PresetBundle::num_physical_filaments() const
+{
+    const auto *opt = project_config.option<ConfigOptionBools>("filament_is_mixed");
+    return opt == nullptr ? filament_presets.size()
+                          : size_t(std::count(opt->values.begin(), opt->values.end(), false));
+}
+
 std::vector<size_t> PresetBundle::physical_filament_config_indices() const
 {
     std::vector<size_t> indices;

src/libslic3r/PresetBundle.hpp

@@ -326,8 +326,9 @@ public:
     // Export selections (current print, current filaments, current printer) into config.ini
     void            export_selections(AppConfig &config);
 
-    // BBS
-    void            set_num_filaments(unsigned int n, std::vector<std::string> new_colors);
+    // n is the total slot count, and growth appends at the raw tail - which is where the mixed
+    // slots live. A caller adding physical filaments has to add num_mixed_filaments() on top and
+    // then move the new slots ahead of the mixed tail, as Sidebar::add_custom_filament does.
     void            set_num_filaments(unsigned int n, std::string new_col = "");
     void         update_num_filaments(unsigned int to_del_flament_id);
 
@@ -503,6 +504,8 @@ public:
     // How many slots are mixed. They sit at the tail of the filament list and have no nozzle of
     // their own, so any resize driven by the printer's extruder count has to add this on top.
     size_t                      num_mixed_filaments() const;
+    // How many slots hold a real filament, i.e. everything ahead of the mixed tail.
+    size_t                      num_physical_filaments() const;
 
     void                        on_extruders_count_changed(int extruder_count);
 

src/slic3r/GUI/GUI_App.cpp

@@ -8906,10 +8906,16 @@ void GUI_App::load_current_presets(bool active_preset_combox/*= false*/, bool ch
         auto* nozzle_diameter = edited_printer_preset.config.option<ConfigOptionFloats>("nozzle_diameter");
         if (nozzle_diameter) {
             // Mixed-color slots are virtual filaments kept at the tail of the list, so they have no
-            // nozzle of their own. Sizing to the nozzle count alone would silently drop the mixes of
-            // a just-loaded project, and update_extruder_count() would then strip the facets painted
-            // with them.
-            preset_bundle->set_num_filaments(nozzle_diameter->values.size() + preset_bundle->num_mixed_filaments());
+            // nozzle of their own and the count has to allow for them. Only ever grow: this sizes
+            // the list so the combo boxes have something to bind to, and set_num_filaments() trims
+            // at the raw tail, so shrinking here would eat the mixes rather than the surplus
+            // physical slots. A list longer than the nozzle count is a state the app reaches
+            // legitimately - raising the extruder count and not saving the printer preset leaves
+            // exactly that on the next start - and losing the project's mixes to it is worse than
+            // carrying a filament the printer has no nozzle for until the count is next changed.
+            const size_t target = nozzle_diameter->values.size() + preset_bundle->num_mixed_filaments();
+            if (target > preset_bundle->filament_presets.size())
+                preset_bundle->set_num_filaments(target);
         }
     }
 	this->plater()->set_printer_technology(printer_technology);

src/slic3r/GUI/Plater.cpp

@@ -5506,12 +5506,15 @@ void Sidebar::add_custom_filament(wxColour new_col, const std::string& preset_na
 
     // Mixed-color slots are kept at the tail of the filament arrays, so a new physical
     // filament has to be inserted just after the last physical one rather than appended.
-    // total == every slot (physical + mixed); insert_pos == the physical slot count.
-    size_t      total          = wxGetApp().preset_bundle->filament_presets.size();
-    size_t      insert_pos     = p->combos_filament.size();
+    // Count off filament_is_mixed, not filament_presets or the combos: the extruder-count spinner
+    // reaches this before the sidebar has rebuilt, and update_multi_material_filament_presets()
+    // can have grown filament_presets alone.
+    auto       *bundle         = wxGetApp().preset_bundle;
+    size_t      insert_pos     = bundle->num_physical_filaments();
+    size_t      total          = insert_pos + bundle->num_mixed_filaments();
     int         filament_count = (int)(total + 1);
     std::string new_color      = new_col.GetAsString(wxC2S_HTML_SYNTAX).ToStdString();
-    wxGetApp().preset_bundle->set_num_filaments(filament_count, new_color);
+    bundle->set_num_filaments(filament_count, new_color);
 
     // Maintain physical-first ordering: rotate the new slot from end to insert_pos.
     // No mixed slots -> insert_pos == total -> every rotate below is a no-op.

src/slic3r/GUI/Tab.cpp

@@ -2174,21 +2174,25 @@ void Tab::on_value_change(const std::string& opt_key, const boost::any& value)
 
     //Orca: sync filament num if it's a multi tool printer
     if (opt_key == "extruders_count" && !m_config->opt_bool("single_extruder_multi_material")){
-        auto num_extruder = boost::any_cast<size_t>(value);
-        int         old_filament_size = wxGetApp().preset_bundle->filament_presets.size();
-        std::vector<std::string> new_colors;
-        for (int i = old_filament_size; i < num_extruder; ++i) {
-            wxColour    new_col   = Plater::get_next_color_for_filament();
-            std::string new_color = new_col.GetAsString(wxC2S_HTML_SYNTAX).ToStdString();
-            new_colors.push_back(new_color);
+        const size_t num_extruder = boost::any_cast<size_t>(value);
+        auto        *bundle       = wxGetApp().preset_bundle;
+        Sidebar     &sidebar      = wxGetApp().plater()->sidebar();
+        // A tool changer feeds filament N from nozzle N, so the extruder count sizes the physical
+        // run only; mixed slots are virtual and keep the tail. Go one slot at a time through the
+        // sidebar's own +/- calls: they insert ahead of the mixed tail and renumber filament ids,
+        // painted facets, custom g-code and mixed components, which a bulk resize clamps away.
+        // Both also refresh the print tab and export the selections, so nothing to do afterwards.
+        size_t physical = bundle->num_physical_filaments();
+        while (physical != num_extruder) {
+            if (physical < num_extruder)
+                sidebar.add_custom_filament(Plater::get_next_color_for_filament());
+            else
+                sidebar.delete_filament(physical - 1);   // physical > num_extruder >= 1
+            const size_t updated = bundle->num_physical_filaments();
+            if (updated == physical)
+                break;   // the call declined, e.g. the total slot limit - do not spin
+            physical = updated;
         }
-        // Mixed-color slots are virtual filaments at the tail of the list with no nozzle of their
-        // own, so they are carried on top of the new extruder count instead of being truncated.
-        const size_t total_filaments = num_extruder + wxGetApp().preset_bundle->num_mixed_filaments();
-        wxGetApp().preset_bundle->set_num_filaments(total_filaments, new_colors);
-        wxGetApp().plater()->on_filament_count_change(total_filaments);
-        wxGetApp().get_tab(Preset::TYPE_PRINT)->update();
-        wxGetApp().preset_bundle->export_selections(*wxGetApp().app_config);
     }
 
     //Orca: disable purge_in_prime_tower if single_extruder_multi_material is disabled

tests/libslic3r/test_preset_bundle_loading.cpp

@@ -704,3 +704,189 @@ TEST_CASE("Sizing the filament list to a multi-tool nozzle count keeps mixed slo
         CHECK(bundle.num_mixed_filaments() == 0);
     }
 }
+
+// The nozzle-count top-up in update_multi_material_filament_presets() grows filament_presets on
+// its own, so a physical count derived from that list reports a slot no per-filament array has
+// yet. That is what made the extruder-count handler conclude there was nothing to add and leave
+// the new sidebar combo with no colour to draw.
+TEST_CASE("The physical filament count is not fooled by a lone filament_presets top-up", "[Preset][Bundle][FilamentMixer]")
+{
+    PresetBundle bundle;
+
+    SECTION("no mixed slots") {
+        bundle.set_num_filaments(4u, std::string("#FF0000"));
+        bundle.printers.get_edited_preset().config.option<ConfigOptionFloats>("nozzle_diameter", true)->values =
+            { 0.4, 0.4, 0.4, 0.4, 0.4 };
+        bundle.update_multi_material_filament_presets();
+
+        REQUIRE(bundle.filament_presets.size() == 5);   // the top-up moved this list on its own
+        REQUIRE(bundle.project_config.option<ConfigOptionStrings>("filament_colour")->values.size() == 4);
+        CHECK(bundle.num_physical_filaments() == 4);
+    }
+
+    SECTION("behind a mixed tail") {
+        bundle.set_num_filaments(5u, std::string("#FF0000"));
+        bundle.project_config.option<ConfigOptionBools>("filament_is_mixed")->values =
+            { false, false, false, false, true };
+        bundle.printers.get_edited_preset().config.option<ConfigOptionFloats>("nozzle_diameter", true)->values =
+            { 0.4, 0.4, 0.4, 0.4, 0.4, 0.4 };
+        bundle.update_multi_material_filament_presets();
+
+        REQUIRE(bundle.filament_presets.size() == 6);
+        REQUIRE(bundle.project_config.option<ConfigOptionStrings>("filament_colour")->values.size() == 5);
+        CHECK(bundle.num_physical_filaments() == 4);
+        CHECK(bundle.num_mixed_filaments() == 1);
+    }
+}
+
+// Which slots are new is a fact about the per-filament arrays, not about filament_presets, for the
+// same reason. Keyed off the wrong one, a freshly opened slot silently keeps filament 1's colour.
+TEST_CASE("New filament colours are placed by array position", "[Preset][Bundle][FilamentMixer]")
+{
+    PresetBundle bundle;
+    bundle.set_num_filaments(4u, std::string("#FF0000"));
+    bundle.printers.get_edited_preset().config.option<ConfigOptionFloats>("nozzle_diameter", true)->values =
+        { 0.4, 0.4, 0.4, 0.4, 0.4 };
+    bundle.update_multi_material_filament_presets();
+    REQUIRE(bundle.filament_presets.size() == 5);
+    REQUIRE(bundle.project_config.option<ConfigOptionStrings>("filament_colour")->values.size() == 4);
+
+    // The call Sidebar::add_custom_filament makes once the extruder count opens a slot.
+    bundle.set_num_filaments(5u, std::string("#00FF00"));
+
+    const auto &colours = bundle.project_config.option<ConfigOptionStrings>("filament_colour")->values;
+    REQUIRE(colours.size() == 5);
+    CHECK(colours[4] == "#00FF00");   // not colours[0], which resize() would have padded with
+}
+
+// The mixed-slot flags are written into the app config on exit and read back on the next start.
+// If the read side loses them the slots survive as filaments but stop being mixes, so the project
+// comes back with the mix showing as an ordinary physical filament.
+TEST_CASE("A saved mix is still a mix after an app restart", "[Preset][Bundle][FilamentMixer]")
+{
+    AppConfig app_config;
+
+    // Last session: a 4-tool project carrying one mix of filaments 2 and 3 at the tail.
+    {
+        PresetBundle bundle;
+        add_inmemory_preset(bundle.printers, "Test Printer");
+        bundle.printers.select_preset_by_name("Test Printer", true);
+        add_inmemory_preset(bundle.filaments, "Test Filament");
+        bundle.filaments.select_preset_by_name("Test Filament", true);
+        bundle.set_num_filaments(5u, std::string("#FF0000"));
+        bundle.filament_presets.assign(5, "Test Filament");
+        bundle.project_config.option<ConfigOptionBools>("filament_is_mixed")->values =
+            { false, false, false, false, true };
+        bundle.project_config.option<ConfigOptionStrings>("filament_mixed_components")->values =
+            { "", "", "", "", "2,3" };
+        bundle.export_selections(app_config);
+
+        REQUIRE(app_config.get_printer_setting("Test Printer", "filament_is_mixed") == "0,0,0,0,1");
+    }
+
+    // This session.
+    PresetBundle bundle;
+    add_inmemory_preset(bundle.printers, "Test Printer");
+    add_inmemory_preset(bundle.filaments, "Test Filament");
+    bundle.load_selections(app_config);
+
+    CHECK(bundle.filament_presets.size() == 5);
+    CHECK(bundle.num_mixed_filaments() == 1);
+    CHECK(bundle.is_mixed_filament(4));
+    CHECK(bundle.project_config.option<ConfigOptionStrings>("filament_mixed_components")->values[4] == "2,3");
+}
+
+// The same restart, on the printer shape that actually shows the bug: a 4-tool changer whose
+// saved filament list is one longer than its nozzle count, because the extra slot is the mix.
+TEST_CASE("A saved mix survives a restart on a multi-tool printer", "[Preset][Bundle][FilamentMixer]")
+{
+    auto make_toolchanger = [](PresetBundle &bundle) -> Preset & {
+        Preset &p = add_inmemory_preset(bundle.printers, "Tool Changer");
+        p.config.option<ConfigOptionFloats>("nozzle_diameter", true)->values = { 0.4, 0.4, 0.4, 0.4 };
+        p.config.option<ConfigOptionBool>("single_extruder_multi_material", true)->value = false;
+        return p;
+    };
+
+    AppConfig app_config;
+    {
+        PresetBundle bundle;
+        make_toolchanger(bundle);
+        bundle.printers.select_preset_by_name("Tool Changer", true);
+        add_inmemory_preset(bundle.filaments, "Test Filament");
+        bundle.filaments.select_preset_by_name("Test Filament", true);
+        bundle.set_num_filaments(5u, std::string("#FF0000"));
+        bundle.filament_presets.assign(5, "Test Filament");
+        bundle.project_config.option<ConfigOptionBools>("filament_is_mixed")->values =
+            { false, false, false, false, true };
+        bundle.project_config.option<ConfigOptionStrings>("filament_mixed_components")->values =
+            { "", "", "", "", "1,2" };
+        bundle.export_selections(app_config);
+        REQUIRE(app_config.get_printer_setting("Tool Changer", "filament_is_mixed") == "0,0,0,0,1");
+    }
+
+    PresetBundle bundle;
+    make_toolchanger(bundle);
+    add_inmemory_preset(bundle.filaments, "Test Filament");
+    bundle.load_selections(app_config);
+
+    CHECK(bundle.filament_presets.size() == 5);
+    CHECK(bundle.num_mixed_filaments() == 1);
+    CHECK(bundle.is_mixed_filament(4));
+
+    SECTION("and through the GUI startup calls that follow it") {
+        // GUI_App::load_current_presets sizes the list for a non-SEMM printer, growing only.
+        const size_t target = 4u + bundle.num_mixed_filaments();
+        if (target > bundle.filament_presets.size())
+            bundle.set_num_filaments(target);
+        CHECK(bundle.num_mixed_filaments() == 1);
+
+        // TabPrinter::extruders_count_changed.
+        bundle.on_extruders_count_changed(4);
+        CHECK(bundle.num_mixed_filaments() == 1);
+
+        // Tab::select_preset re-reads the snapshot when remember_printer_config is on.
+        bundle.update_selections(app_config);
+        CHECK(bundle.filament_presets.size() == 5);
+        CHECK(bundle.num_mixed_filaments() == 1);
+        CHECK(bundle.is_mixed_filament(4));
+    }
+}
+
+// The startup sizing in GUI_App::load_current_presets targets the nozzle count plus the mixes.
+// That is a floor, never a ceiling: set_num_filaments() trims at the raw tail, which is exactly
+// where the mixes live, so applying the target to a longer list deletes them. A list longer than
+// the target is reachable - raising the extruder count without saving the printer preset leaves
+// the extra physical slot behind on the next start - so the startup sizing must only ever grow.
+TEST_CASE("Sizing down to the nozzle count plus mixes is what eats the mixed tail", "[Preset][Bundle][FilamentMixer]")
+{
+    // 5 physical + 1 mix, on a printer preset still reporting 4 nozzles.
+    const size_t nozzle_count = 4;
+    PresetBundle bundle;
+    bundle.set_num_filaments(6u, std::string("#FF0000"));
+    bundle.project_config.option<ConfigOptionBools>("filament_is_mixed")->values =
+        { false, false, false, false, false, true };
+    bundle.project_config.option<ConfigOptionStrings>("filament_mixed_components")->values =
+        { "", "", "", "", "", "1,2" };
+    REQUIRE(bundle.num_physical_filaments() == 5);
+
+    const size_t target = nozzle_count + bundle.num_mixed_filaments();
+    REQUIRE(target < bundle.filament_presets.size());
+
+    SECTION("applied as written, the mix is gone and every slot reads physical") {
+        bundle.set_num_filaments(target);
+
+        CHECK(bundle.filament_presets.size() == target);
+        CHECK(bundle.num_mixed_filaments() == 0);
+        CHECK(bundle.num_physical_filaments() == target);
+    }
+
+    SECTION("applied as a floor, the mix is left alone") {
+        if (target > bundle.filament_presets.size())
+            bundle.set_num_filaments(target);
+
+        CHECK(bundle.filament_presets.size() == 6);
+        CHECK(bundle.num_mixed_filaments() == 1);
+        CHECK(bundle.is_mixed_filament(5));
+        CHECK(bundle.project_config.option<ConfigOptionStrings>("filament_mixed_components")->values[5] == "1,2");
+    }
+}