DoubleSlider modes(states) are extended and implemented mode detection from model

+ Some code refactoring

src/slic3r/GUI/GUI_Preview.cpp

@@ -692,7 +692,11 @@ void Preview::update_double_slider(const std::vector<double>& layers_z, bool kee
     bool color_print_enable = (wxGetApp().plater()->printer_technology() == ptFFF);
 
     m_slider->EnableTickManipulation(color_print_enable);
-    m_slider->SetManipulationState(wxGetApp().extruders_edited_cnt());
+
+    // Detect and set manipulation mode for double slider
+    m_slider->SetManipulationState( wxGetApp().extruders_edited_cnt() == 1               ? DoubleSlider::msSingleExtruder :
+                                    wxGetApp().plater()->is_one_extruder_printed_model() ? DoubleSlider::msMultiAsSingle :
+                                                                                           DoubleSlider::msMultiExtruder);
 }
 
 void Preview::reset_double_slider()

src/slic3r/GUI/Plater.cpp

@@ -5358,6 +5358,38 @@ bool Plater::is_export_gcode_scheduled() const
     return p->background_process.is_export_scheduled();
 }
 
+bool Plater::is_one_extruder_printed_model()
+{
+    if (wxGetApp().extruders_edited_cnt() == 1)
+        return true;    
+
+    // check if model use just one extruder
+    const ModelObjectPtrs& objects = p->model.objects;
+    if (!objects.empty())
+    {
+        const size_t extruder = objects[0]->config.has("extruder") ? 
+                                objects[0]->config.option("extruder")->getInt() : 0;
+        for (ModelObject* object : objects)
+        {
+            if (object->config.has("extruder") &&
+                object->config.option("extruder")->getInt() != extruder)
+                return false;
+
+            for (ModelVolume* volume : object->volumes)
+                if (volume->config.has("extruder") &&
+                    volume->config.option("extruder")->getInt() != extruder)
+                    return false;
+
+            for (const auto& range : object->layer_config_ranges)
+                if (range.second.has("extruder") &&
+                    range.second.option("extruder")->getInt() != extruder)
+                return false;
+        }
+    }
+
+    return true;
+}
+
 int Plater::get_selected_object_idx()
 {
     return p->get_selected_object_idx();

src/slic3r/GUI/Plater.hpp

@@ -234,6 +234,7 @@ public:
     void set_project_filename(const wxString& filename);
 
     bool is_export_gcode_scheduled() const;
+    bool is_one_extruder_printed_model();
 
     int get_selected_object_idx();
     bool is_single_full_object_selection() const;

src/slic3r/GUI/wxExtensions.cpp

@@ -2861,13 +2861,13 @@ void DoubleSlider::draw_colored_band(wxDC& dc)
 
     const wxColour bg_clr = GetParent()->GetBackgroundColour();
 
-    wxColour clr = m_state == msSingleExtruder ? wxColour(colors[0]) : bg_clr;
+    wxColour clr = m_ticks_.empty() ? bg_clr : wxColour(colors[0]);
     draw_band(dc, clr, main_band);
 
     size_t i = 1;
     for (auto tick : m_ticks_)
     {
-        if ( (m_state == msSingleExtruder && tick.gcode != Slic3r::ColorChangeCode) ||
+        if ( (m_state != msMultiExtruder/*m_state == msSingleExtruder*/ && tick.gcode != Slic3r::ColorChangeCode) ||
              (m_state == msMultiExtruder && tick.gcode != Slic3r::ExtruderChangeCode) )
             continue;
 
@@ -3182,31 +3182,50 @@ void DoubleSlider::OnLeftUp(wxMouseEvent& event)
 
     if (m_show_context_menu)
     {
-        if (m_state == msMultiExtruder)
+        if (m_state == msSingleExtruder)
+            add_code(Slic3r::ColorChangeCode);
+        else
         {
-            wxMenu menu;
             const int extruders_cnt = Slic3r::GUI::wxGetApp().extruders_edited_cnt();
             if (extruders_cnt > 1)
             {            
-                const int initial_extruder = get_extruder_for_tick(m_selection == ssLower ? m_lower_value : m_higher_value);
+                wxMenu menu;
+                wxMenu* sub_menu = new wxMenu();
+                wxString sub_menu_name = _(L("Change extruder"));
+                std::string menu_icon_name = "change_extruder";
 
-                wxMenu* change_extruder_menu = new wxMenu();
+                if (m_state == msMultiAsSingle)
+                {
+                    int initial_extruder = get_extruder_for_tick(m_selection == ssLower ? m_lower_value : m_higher_value);
+                    if (initial_extruder == 0)
+                        initial_extruder = 1;
 
-                for (int i = 0; i <= extruders_cnt; i++) {
+                    for (int i = /*0*/1; i <= extruders_cnt; i++) {
-                    const wxString item_name = i == 0 ? _(L("Default")) : wxString::Format(_(L("Extruder %d")), i);
+                        const wxString item_name = i == 0 ? _(L("Default")) : wxString::Format(_(L("Extruder %d")), i);
 
-                    append_menu_radio_item(change_extruder_menu, wxID_ANY, item_name, "",
+                        append_menu_radio_item(sub_menu, wxID_ANY, item_name, "",
-                        [this, i](wxCommandEvent&) { change_extruder(i); }, &menu)->Check(i == initial_extruder);
+                            [this, i](wxCommandEvent&) { change_extruder(i); }, &menu)->Check(i == initial_extruder);
+                    }
+                }
+                else
+                {
+                    for (int i = 1; i <= extruders_cnt; i++) {
+                        const wxString item_name = wxString::Format(_(L("Extruder %d")), i);
+
+                        append_menu_item(sub_menu, wxID_ANY, item_name, "",
+                            [this, i](wxCommandEvent&) { add_code(Slic3r::ColorChangeCode, i); }, "", &menu);
+                    }
+
+                    sub_menu_name = from_u8((boost::format(_utf8(L("Add color change (%1%) for:"))) % Slic3r::ColorChangeCode).str());
+                    menu_icon_name = "colorchange_add_m";
                 }
 
-                wxMenuItem* change_extruder_menu_item = menu.AppendSubMenu(change_extruder_menu, _(L("Change extruder")), _(L("Use another extruder")));
+                wxMenuItem* sub_menu_item = menu.AppendSubMenu(sub_menu, sub_menu_name, "");
-                change_extruder_menu_item->SetBitmap(create_scaled_bitmap(nullptr, "change_extruder"));
+                sub_menu_item->SetBitmap(create_scaled_bitmap(this, menu_icon_name));
-            }
 
-            Slic3r::GUI::wxGetApp().plater()->PopupMenu(&menu);
+                Slic3r::GUI::wxGetApp().plater()->PopupMenu(&menu);
+            }
         }
-        else
-            add_code(Slic3r::ColorChangeCode);
         
         m_show_context_menu = false;
     }

src/slic3r/GUI/wxExtensions.hpp

@@ -823,7 +823,10 @@ public:
 
     enum ManipulationState {
         msSingleExtruder,   // single extruder printer preset is selected
-        msMultiExtruder     // multiple extruder printer preset is selected, and "Whole print" is selected 
+        msMultiAsSingle,    // multiple extruder printer preset is selected, but 
+                            // this mode works just for Single extruder print 
+                            // (For all print from objects settings is used just one extruder) 
+        msMultiExtruder     // multiple extruder printer preset is selected
     };
     void SetManipulationState(ManipulationState state) {
         m_state = state;
@@ -976,31 +979,11 @@ private:
 public:
     struct ExtrudersSequence
     {
-        bool            is_mm_intervals;
+        bool            is_mm_intervals     = true;
-        double          interval_by_mm;
+        double          interval_by_mm      = 3.0;
-        int             interval_by_layers;
+        int             interval_by_layers  = 10;
-        std::vector<size_t>  extruders;
+        std::vector<size_t>  extruders      = { 0 };
 
-        ExtrudersSequence() :
-            is_mm_intervals(true),
-            interval_by_mm(3.0),
-            interval_by_layers(10),
-            extruders({ 0 }) {}
-
-        ExtrudersSequence(const ExtrudersSequence& other) :
-            is_mm_intervals(other.is_mm_intervals),
-            interval_by_mm(other.interval_by_mm),
-            interval_by_layers(other.interval_by_layers),
-            extruders(other.extruders) {}
-
-        ExtrudersSequence& operator=(const ExtrudersSequence& other) {
-            this->is_mm_intervals   = other.is_mm_intervals;
-            this->interval_by_mm    = other.interval_by_mm;
-            this->interval_by_layers= other.interval_by_layers;
-            this->extruders         = other.extruders;
-
-            return *this;
-        }
         bool operator==(const ExtrudersSequence& other) const
         {
             return  (other.is_mm_intervals      == this->is_mm_intervals    ) &&