feat(gui): add purge mode selector dialog

The engine already implements prime_volume_mode (Default/Saving/Fast)
but nothing in the UI could set it, leaving prime-saving unreachable on
multi-sub-nozzle extruders and fast purge unreachable on printers that
support it.

- new PurgeModeDialog with selectable Standard/Fast or
  Standard/Prime Saving cards depending on printer capability
- "Purge mode" sidebar button next to Flushing volumes; opens the
  dialog and stores the choice in the project config
- printer preset-load gating: button shown only when the printer has
  multiple sub-nozzles per extruder or sets support_fast_purge_mode;
  stale project values the printer cannot honor reset to Default
- enable fast purge on A2L 0.4 (support_fast_purge_mode), explicit
  default 0 in the common machine base
- new dialog strings added to OrcaSlicer.pot

Printers without these capabilities never show the button and their
projects keep prime_volume_mode at Default, so slicing output is
unchanged.

src/slic3r/CMakeLists.txt

@@ -411,6 +411,8 @@ set(SLIC3R_GUI_SOURCES
     GUI/Project.hpp
     GUI/PublishDialog.cpp
     GUI/PublishDialog.hpp
+    GUI/PurgeModeDialog.cpp
+    GUI/PurgeModeDialog.hpp
     GUI/RammingChart.cpp
     GUI/RammingChart.hpp
     GUI/RecenterDialog.cpp

src/slic3r/GUI/Plater.cpp

@@ -170,6 +170,7 @@
 #include "StepMeshDialog.hpp"
 #include "FilamentMapDialog.hpp"
 #include "CloneDialog.hpp"
+#include "PurgeModeDialog.hpp"
 
 #include "DeviceCore/DevFilaSystem.h"
 #include "DeviceCore/DevManager.h"
@@ -551,6 +552,7 @@ struct Sidebar::priv
     wxStaticLine* m_staticline2;
     wxPanel* m_panel_project_title;
     ScalableButton* m_filament_icon = nullptr;
+    Button * m_purge_mode_btn = nullptr;
     Button * m_flushing_volume_btn = nullptr;
     TextInput* m_search_item = nullptr;
     StaticBox* m_search_bar = nullptr;
@@ -2663,12 +2665,13 @@ Sidebar::Sidebar(Plater *parent)
     p->m_panel_filament_title->SetBackgroundColor(title_bg);
     p->m_panel_filament_title->SetBackgroundColor2(0xF1F1F1);
     p->m_panel_filament_title->Bind(wxEVT_LEFT_UP, [this](wxMouseEvent &e) {
-        if (!p || !p->m_panel_filament_content || !m_scrolled_sizer || !p->m_bpButton_set_filament || !p->m_flushing_volume_btn || !p->m_bpButton_add_filament || !ams_btn)
+        if (!p || !p->m_panel_filament_content || !m_scrolled_sizer || !p->m_bpButton_set_filament || !p->m_purge_mode_btn || !p->m_flushing_volume_btn || !p->m_bpButton_add_filament || !ams_btn)
             return;
         // ORCA exclude area of del button from titlebar collapse/expand feature to fix undesired collapse when user spams del filament button
         // also block fold/unfold feature when user clicks to spacing between icons
         int exclude_pt = p->m_bpButton_set_filament->GetPosition().x; // maximum fixed item
-        if      (p->m_flushing_volume_btn->IsShown())   exclude_pt = p->m_flushing_volume_btn->GetPosition().x;
+        if      (p->m_purge_mode_btn->IsShown())        exclude_pt = p->m_purge_mode_btn->GetPosition().x;
+        else if (p->m_flushing_volume_btn->IsShown())   exclude_pt = p->m_flushing_volume_btn->GetPosition().x;
         else if (p->m_bpButton_add_filament->IsShown()) exclude_pt = p->m_bpButton_add_filament->GetPosition().x - FromDIP(30); // reserve spacing for delete button
         else if (ams_btn->IsShown())                    exclude_pt = ams_btn->GetPosition().x;
         if (e.GetPosition().x > exclude_pt)
@@ -2703,6 +2706,24 @@ Sidebar::Sidebar(Plater *parent)
 
     bSizer39->AddStretchSpacer(1);
 
+    p->m_purge_mode_btn = new Button(p->m_panel_filament_title, _L("Purge mode"));
+    p->m_purge_mode_btn->SetStyle(ButtonStyle::Confirm, ButtonType::Compact);
+
+    p->m_purge_mode_btn->Bind(wxEVT_BUTTON, [](wxCommandEvent &e) {
+        auto &preset_bundle         = *wxGetApp().preset_bundle;
+        auto support_fast_purge_opt = preset_bundle.printers.get_edited_preset().config.option<ConfigOptionBool>("support_fast_purge_mode");
+        bool support_fast_purge     = support_fast_purge_opt ? support_fast_purge_opt->value : false;
+        auto dlg_type               = support_fast_purge ? PurgeModeDialogType::FastMode : PurgeModeDialogType::MultiNozzle;
+        PurgeModeDialog dlg(static_cast<wxWindow *>(wxGetApp().mainframe), dlg_type);
+        if (dlg.ShowModal() == wxID_OK) {
+            preset_bundle.project_config.set_key_value("prime_volume_mode", new ConfigOptionEnum<PrimeVolumeMode>(dlg.get_selected_mode()));
+            wxGetApp().plater()->update();
+        }
+    });
+
+    bSizer39->Add(p->m_purge_mode_btn, 0, wxALIGN_CENTER_VERTICAL | wxLEFT, FromDIP(4));
+    bSizer39->Hide(p->m_purge_mode_btn); // hidden on launch; shown only for printers that support purge mode selection
+
     // BBS
     // add wiping dialog
     //wiping_dialog_button->SetFont(wxGetApp().normal_font());
@@ -3572,6 +3593,7 @@ void Sidebar::msw_rescale()
     p->m_bpButton_del_filament->msw_rescale();
     p->m_bpButton_ams_filament->msw_rescale();
     p->m_bpButton_set_filament->msw_rescale();
+    p->m_purge_mode_btn->Rescale();
     p->m_flushing_volume_btn->Rescale();
     set_flushing_volume_warning(is_flush_config_modified()); // ORCA reapply appearance
 
@@ -3657,6 +3679,7 @@ void Sidebar::sys_color_changed()
     p->m_bpButton_del_filament->msw_rescale();
     p->m_bpButton_ams_filament->msw_rescale();
     p->m_bpButton_set_filament->msw_rescale();
+    p->m_purge_mode_btn->Rescale();
     p->m_flushing_volume_btn->Rescale();
     set_flushing_volume_warning(is_flush_config_modified()); // ORCA reapply appearance
 
@@ -4426,6 +4449,17 @@ void Sidebar::show_SEMM_buttons()
     Layout();
 }
 
+void Sidebar::enable_purge_mode_btn(bool enable)
+{
+    if (!p || !p->m_purge_mode_btn)
+        return;
+    p->m_purge_mode_btn->Show(enable);
+    wxGetApp().CallAfter([this]() {
+        p->m_panel_filament_title->Layout();
+        this->Layout();
+    });
+}
+
 void Sidebar::update_dynamic_filament_list()
 {
     dynamic_filament_list.update();

src/slic3r/GUI/Plater.hpp

@@ -208,6 +208,7 @@ public:
     // Orca
     static bool should_show_SEMM_buttons();
     void show_SEMM_buttons();
+    void enable_purge_mode_btn(bool enable);
     void update_dynamic_filament_list();
 
     PlaterPresetComboBox *  printer_combox();

src/slic3r/GUI/PurgeModeDialog.cpp

@@ -0,0 +1,269 @@
+#include "PurgeModeDialog.hpp"
+
+#include <wx/sizer.h>
+#include <wx/stattext.h>
+#include <wx/statbmp.h>
+#include <wx/dcbuffer.h>
+#include <wx/graphics.h>
+
+#include "I18N.hpp"
+#include "GUI_App.hpp"
+#include "wxExtensions.hpp"
+#include "Widgets/Button.hpp"
+#include "libslic3r/Utils.hpp"
+
+namespace Slic3r { namespace GUI {
+
+static const wxColour BgNormalColor = wxColour("#FFFFFF");
+static const wxColour BgSelectColor = wxColour("#EBF9F0");
+
+static const wxColour BorderNormalColor   = wxColour("#CECECE");
+static const wxColour BorderSelectedColor = wxColour("#00AE42");
+
+static const wxColour TextNormalBlackColor = wxColour("#262E30");
+static const wxColour TextNormalGreyColor  = wxColour("#6B6B6B");
+
+PurgeModeDialog::PurgeModeDialog(wxWindow *parent, PurgeModeDialogType dialog_type)
+    : DPIDialog(parent, wxID_ANY, _L("Purge Mode Settings"), wxDefaultPosition, wxDefaultSize, wxDEFAULT_DIALOG_STYLE), m_dialog_type(dialog_type)
+{
+    SetBackgroundColour(*wxWHITE);
+    SetMinSize(wxSize(FromDIP(520), FromDIP(320)));
+    SetMaxSize(wxSize(FromDIP(520), FromDIP(320)));
+    std::string icon_path = (boost::format("%1%/images/OrcaSlicerTitle.ico") % resources_dir()).str();
+    SetIcon(wxIcon(encode_path(icon_path.c_str()), wxBITMAP_TYPE_ICO));
+
+    auto main_sizer = new wxBoxSizer(wxVERTICAL);
+
+    auto options_panel = new wxPanel(this);
+    auto options_sizer = new wxBoxSizer(wxVERTICAL);
+    auto panels_sizer  = new wxBoxSizer(wxHORIZONTAL);
+
+    auto           &preset_bundle = *wxGetApp().preset_bundle;
+    auto            current_mode  = preset_bundle.project_config.option<ConfigOptionEnum<PrimeVolumeMode>>("prime_volume_mode");
+    PrimeVolumeMode mode          = current_mode ? current_mode->value : pvmDefault;
+    m_selected_mode               = mode;
+
+    bool is_fast_mode = (m_dialog_type == PurgeModeDialogType::FastMode);
+
+    m_standard_panel = new PurgeModeBtnPanel(options_panel, _L("Standard"), _L("Perform full purging with speed and temperature transition for the best print quality."),
+                                             "shield");
+    m_standard_panel->SetMinSize(wxSize(FromDIP(200), FromDIP(150)));
+    m_standard_panel->Select(mode == pvmDefault);
+    m_standard_panel->Bind(wxEVT_LEFT_DOWN, [this](wxMouseEvent &) { select_option(pvmDefault); });
+    panels_sizer->Add(m_standard_panel, 1, wxEXPAND | wxRIGHT, FromDIP(12));
+    if (is_fast_mode) {
+        m_saving_panel = new PurgeModeBtnPanel(options_panel, _L("Fast"),
+                                               _L("Uses optimized purge temperature, multiplier and stronger extrusion for faster purging. May cause slight color mixing in some extreme cases."), "leaf");
+        m_saving_panel->SetMinSize(wxSize(FromDIP(200), FromDIP(150)));
+        m_saving_panel->Select(mode == pvmFast);
+        m_saving_panel->Bind(wxEVT_LEFT_DOWN, [this](wxMouseEvent &) { select_option(pvmFast); });
+    } else {
+        m_saving_panel = new PurgeModeBtnPanel(options_panel, _L("Prime Saving"),
+                                               _L("Reduces prime waste and prints faster. May cause slight color mixing or small surface defects."), "leaf");
+        m_saving_panel->SetMinSize(wxSize(FromDIP(200), FromDIP(150)));
+        m_saving_panel->Select(mode == pvmSaving);
+        m_saving_panel->Bind(wxEVT_LEFT_DOWN, [this](wxMouseEvent &) { select_option(pvmSaving); });
+    }
+
+    panels_sizer->Add(m_saving_panel, 1, wxEXPAND | wxLEFT, FromDIP(12));
+
+    options_sizer->Add(panels_sizer, 0, wxEXPAND | wxALL, FromDIP(20));
+
+    options_panel->SetSizer(options_sizer);
+    main_sizer->Add(options_panel, 1, wxEXPAND);
+
+    auto btn_sizer = new wxBoxSizer(wxHORIZONTAL);
+    btn_sizer->AddStretchSpacer();
+
+    auto ok_btn = new Button(this, _L("Confirm"));
+    ok_btn->SetStyle(ButtonStyle::Confirm, ButtonType::Compact);
+    ok_btn->SetId(wxID_OK);
+
+    auto cancel_btn = new Button(this, _L("Cancel"));
+    cancel_btn->SetStyle(ButtonStyle::Regular, ButtonType::Compact);
+    cancel_btn->SetId(wxID_CANCEL);
+
+    btn_sizer->Add(ok_btn, 0, wxRIGHT, FromDIP(12));
+    btn_sizer->Add(cancel_btn, 0);
+
+    main_sizer->Add(btn_sizer, 0, wxEXPAND | wxALL, FromDIP(20));
+
+    SetSizer(main_sizer);
+    Fit();
+    CenterOnParent();
+
+    wxGetApp().UpdateDlgDarkUI(this);
+}
+
+void PurgeModeDialog::select_option(PrimeVolumeMode mode)
+{
+    m_selected_mode = mode;
+    update_panel_selection();
+}
+
+void PurgeModeDialog::update_panel_selection()
+{
+    if (m_selected_mode == pvmDefault) {
+        m_standard_panel->Select(true);
+        m_saving_panel->Select(false);
+    } else {
+        m_standard_panel->Select(false);
+        m_saving_panel->Select(true);
+    }
+}
+
+void PurgeModeDialog::on_dpi_changed(const wxRect &suggested_rect)
+{
+    const int &em = em_unit();
+
+    msw_buttons_rescale(this, em, {wxID_OK, wxID_CANCEL});
+
+    const wxSize &size = wxSize(70 * em, 32 * em);
+    SetMinSize(size);
+
+    Fit();
+    Refresh();
+}
+
+PurgeModeBtnPanel::PurgeModeBtnPanel(wxWindow *parent, const wxString &label, const wxString &detail, const std::string &icon_path) : wxPanel(parent)
+{
+    SetBackgroundColour(*wxWHITE);
+    SetBackgroundStyle(wxBG_STYLE_PAINT);
+
+    const int horizontal_margin = FromDIP(12);
+
+    auto sizer = new wxBoxSizer(wxVERTICAL);
+
+    icon  = create_scaled_bitmap(icon_path, nullptr, 20);
+    m_btn = new wxStaticBitmap(this, wxID_ANY, icon, wxDefaultPosition, wxDefaultSize, wxNO_BORDER);
+
+    check_icon  = create_scaled_bitmap("completed_2", nullptr, 20);
+    m_check_btn = new wxStaticBitmap(this, wxID_ANY, check_icon, wxDefaultPosition, wxDefaultSize, wxNO_BORDER);
+    m_check_btn->Hide();
+
+    auto icon_sizer = new wxBoxSizer(wxHORIZONTAL);
+    icon_sizer->Add(m_btn, 0, wxALIGN_CENTER_VERTICAL | wxLEFT, horizontal_margin);
+    icon_sizer->AddStretchSpacer();
+    icon_sizer->Add(m_check_btn, 0, wxALIGN_CENTER_VERTICAL | wxRIGHT, horizontal_margin);
+
+    m_label = new wxStaticText(this, wxID_ANY, label);
+    m_label->SetFont(Label::Head_14);
+    m_label->SetForegroundColour(TextNormalBlackColor);
+
+    auto label_sizer = new wxBoxSizer(wxHORIZONTAL);
+    label_sizer->Add(m_label, 0, wxALIGN_CENTER_VERTICAL | wxLEFT, horizontal_margin);
+
+    auto detail_sizer = new wxBoxSizer(wxHORIZONTAL);
+    m_detail          = new Label(this, detail);
+    m_detail->SetFont(Label::Body_12);
+    m_detail->SetForegroundColour(TextNormalGreyColor);
+    m_detail->Wrap(FromDIP(200));
+    detail_sizer->Add(m_detail, 0, wxALIGN_CENTER_VERTICAL | wxLEFT | wxRIGHT, horizontal_margin);
+
+    sizer->AddSpacer(FromDIP(15));
+    sizer->Add(icon_sizer, 0, wxEXPAND);
+    sizer->AddSpacer(FromDIP(10));
+    sizer->Add(label_sizer, 0, wxEXPAND);
+    sizer->AddSpacer(FromDIP(6));
+    sizer->Add(detail_sizer, 0, wxEXPAND);
+    sizer->AddSpacer(FromDIP(10));
+
+    SetSizer(sizer);
+    Layout();
+    Fit();
+
+    wxGetApp().UpdateDarkUIWin(this);
+
+    // Clicks on child widgets must select the whole card, so re-dispatch them on the panel.
+    auto forward_click_to_parent = [this](wxMouseEvent &) {
+        wxCommandEvent click_event(wxEVT_LEFT_DOWN, GetId());
+        click_event.SetEventObject(this);
+        this->ProcessEvent(click_event);
+    };
+
+    m_btn->Bind(wxEVT_LEFT_DOWN, forward_click_to_parent);
+    m_label->Bind(wxEVT_LEFT_DOWN, forward_click_to_parent);
+    m_detail->Bind(wxEVT_LEFT_DOWN, forward_click_to_parent);
+
+    Bind(wxEVT_PAINT, &PurgeModeBtnPanel::OnPaint, this);
+    Bind(wxEVT_ENTER_WINDOW, &PurgeModeBtnPanel::OnEnterWindow, this);
+    Bind(wxEVT_LEAVE_WINDOW, &PurgeModeBtnPanel::OnLeaveWindow, this);
+}
+
+void PurgeModeBtnPanel::OnPaint(wxPaintEvent &event)
+{
+    wxAutoBufferedPaintDC dc(this);
+    wxGraphicsContext    *gc = wxGraphicsContext::Create(dc);
+
+    if (gc) {
+        dc.Clear();
+        wxRect rect = GetClientRect();
+        gc->SetBrush(wxTransparentColour);
+        gc->DrawRoundedRectangle(0, 0, rect.width, rect.height, 0);
+        wxColour bg_color = m_selected ? BgSelectColor : BgNormalColor;
+
+        wxColour border_color = m_hover || m_selected ? BorderSelectedColor : BorderNormalColor;
+
+        bg_color     = StateColor::darkModeColorFor(bg_color);
+        border_color = StateColor::darkModeColorFor(border_color);
+        gc->SetBrush(wxBrush(bg_color));
+        gc->SetPen(wxPen(border_color, 1));
+        gc->DrawRoundedRectangle(1, 1, rect.width - 2, rect.height - 2, 8);
+        delete gc;
+    }
+}
+
+void PurgeModeBtnPanel::UpdateStatus()
+{
+    if (m_selected) {
+        m_btn->SetBackgroundColour(BgSelectColor);
+        m_label->SetBackgroundColour(BgSelectColor);
+        m_detail->SetBackgroundColour(BgSelectColor);
+        if (m_check_btn) {
+            m_check_btn->SetBackgroundColour(BgSelectColor);
+            m_check_btn->Show();
+        }
+    } else {
+        m_btn->SetBackgroundColour(BgNormalColor);
+        m_label->SetBackgroundColour(BgNormalColor);
+        m_detail->SetBackgroundColour(BgNormalColor);
+        if (m_check_btn) {
+            m_check_btn->SetBackgroundColour(BgNormalColor);
+            m_check_btn->Hide();
+        }
+    }
+    Layout();
+    Refresh();
+    wxGetApp().UpdateDarkUIWin(this);
+}
+
+void PurgeModeBtnPanel::OnEnterWindow(wxMouseEvent &event)
+{
+    if (!m_hover) {
+        m_hover = true;
+        UpdateStatus();
+        Refresh();
+        event.Skip();
+    }
+}
+
+void PurgeModeBtnPanel::OnLeaveWindow(wxMouseEvent &event)
+{
+    if (m_hover) {
+        wxPoint pos = this->ScreenToClient(wxGetMousePosition());
+        if (this->GetClientRect().Contains(pos)) return;
+        m_hover = false;
+        UpdateStatus();
+        Refresh();
+        event.Skip();
+    }
+}
+
+void PurgeModeBtnPanel::Select(bool selected)
+{
+    m_selected = selected;
+    UpdateStatus();
+    Refresh();
+}
+
+}} // namespace Slic3r::GUI

src/slic3r/GUI/PurgeModeDialog.hpp

@@ -0,0 +1,69 @@
+#pragma once
+
+#include <wx/dialog.h>
+#include <wx/panel.h>
+
+#include "GUI_Utils.hpp"
+#include "libslic3r/PrintConfig.hpp"
+#include "Widgets/Label.hpp"
+
+class wxStaticText;
+class wxStaticBitmap;
+
+namespace Slic3r {
+
+namespace GUI {
+
+class PurgeModeBtnPanel : public wxPanel
+{
+public:
+    PurgeModeBtnPanel(wxWindow *parent, const wxString &label, const wxString &detail, const std::string &icon_path);
+    void Select(bool selected);
+
+protected:
+    void OnPaint(wxPaintEvent &event);
+
+private:
+    void OnEnterWindow(wxMouseEvent &event);
+    void OnLeaveWindow(wxMouseEvent &event);
+
+    void UpdateStatus();
+
+    wxBitmap icon;
+    wxBitmap check_icon;
+
+    wxStaticBitmap *m_btn;
+    wxStaticBitmap *m_check_btn;
+    wxStaticText   *m_label;
+    Label          *m_detail;
+    bool            m_hover{false};
+    bool            m_selected{false};
+};
+
+enum class PurgeModeDialogType {
+    MultiNozzle,
+    FastMode
+};
+
+class PurgeModeDialog : public DPIDialog
+{
+public:
+    PurgeModeDialog(wxWindow *parent, PurgeModeDialogType dialog_type = PurgeModeDialogType::MultiNozzle);
+
+    PrimeVolumeMode get_selected_mode() const { return m_selected_mode; }
+
+protected:
+    void on_dpi_changed(const wxRect &suggested_rect) override;
+
+private:
+    void select_option(PrimeVolumeMode mode);
+    void update_panel_selection();
+
+    PurgeModeBtnPanel  *m_standard_panel;
+    PurgeModeBtnPanel  *m_saving_panel;
+    PrimeVolumeMode     m_selected_mode;
+    PurgeModeDialogType m_dialog_type;
+};
+
+} // namespace GUI
+} // namespace Slic3r

src/slic3r/GUI/Tab.cpp

@@ -5656,6 +5656,27 @@ void TabPrinter::on_preset_loaded()
         if (wxGetApp().plater())
             wxGetApp().plater()->sidebar().reset_fila_switch();
     }
+
+    // Purge mode selection is only meaningful for printers with multiple sub-nozzles per
+    // extruder (prime saving) or fast-purge support; reset stale project values that the
+    // current printer cannot honor and toggle the sidebar button accordingly.
+    auto extruder_max_nozzle_count = current_printer.config.option<ConfigOptionIntsNullable>("extruder_max_nozzle_count");
+    bool has_multiple_nozzle = extruder_max_nozzle_count &&
+        std::any_of(extruder_max_nozzle_count->values.begin(), extruder_max_nozzle_count->values.end(),
+                    [](int v) { return v > 1 && v != ConfigOptionIntsNullable::nil_value(); });
+    auto support_fast_purge_opt = current_printer.config.option<ConfigOptionBool>("support_fast_purge_mode");
+    bool support_fast_purge     = support_fast_purge_opt ? support_fast_purge_opt->value : false;
+    bool show_purge_mode        = has_multiple_nozzle || support_fast_purge;
+    if (auto *prime_volume_mode = m_preset_bundle->project_config.option<ConfigOptionEnum<PrimeVolumeMode>>("prime_volume_mode")) {
+        if (!show_purge_mode)
+            prime_volume_mode->value = PrimeVolumeMode::pvmDefault;
+        else if (!has_multiple_nozzle && prime_volume_mode->value == PrimeVolumeMode::pvmSaving)
+            prime_volume_mode->value = PrimeVolumeMode::pvmDefault;
+        else if (!support_fast_purge && prime_volume_mode->value == PrimeVolumeMode::pvmFast)
+            prime_volume_mode->value = PrimeVolumeMode::pvmDefault;
+    }
+    if (wxGetApp().plater())
+        wxGetApp().plater()->sidebar().enable_purge_mode_btn(show_purge_mode);
 }
 
 void TabPrinter::update_pages()