DoubleSlider: Code refactoring for auto color change

src/slic3r/GUI/DoubleSlider.cpp

@@ -38,6 +38,25 @@ using GUI::format_wxstr;
 
 namespace DoubleSlider {
 
+bool possible_threshold(const double& bottom_area, const double& top_area)
+{
+            // Check percent of the area decrease. 
+            // This value have to be more than 25 mm2
+    return  (bottom_area - top_area > min_delta_area()) &&
+            // and more 10%
+            (top_area / bottom_area < 0.9);
+}
+
+bool equivalent_areas(const double& bottom_area, const double& top_area)
+{
+    return fabs(bottom_area - top_area <= min_threshold());
+}
+
+bool overhang(const double& bottom_area, const double& top_area)
+{
+    return top_area > bottom_area && !equivalent_areas(bottom_area, top_area);
+}
+
 wxDEFINE_EVENT(wxCUSTOMEVT_TICKSCHANGED, wxEvent);
 
 static std::string gcode(Type type)
@@ -2049,8 +2068,6 @@ void Control::auto_color_change()
     int extruder = 2;
 
     const Print& print = GUI::wxGetApp().plater()->fff_print();  
-    double delta_area = scale_(scale_(25)); // equal to 25 mm2
-
     for (auto object : print.objects()) {
         if (object->layer_count() == 0)
             continue;
@@ -2060,14 +2077,10 @@ void Control::auto_color_change()
             Layer* layer = object->get_layer(i);
             double cur_area = area(layer->lslices);
 
-            if (cur_area > prev_area && prev_area - cur_area > scale_(scale_(1)))
+            if (overhang(prev_area, cur_area))
                 break;
 
-            if (prev_area - cur_area > delta_area) {
+            if (possible_threshold(prev_area, cur_area)) {
-                // Check percent of the area decrease. 
-                // Ignore it, if this value is less than 10% 
-                if (cur_area / prev_area > 0.9)
-                    continue;
                 int tick = get_tick_from_value(layer->print_z);
                 if (tick >= 0 && !m_ticks.has_tick(tick)) {
                     if (m_mode == SingleExtruder) {

src/slic3r/GUI/DoubleSlider.hpp

@@ -25,6 +25,13 @@ namespace DoubleSlider {
  */
 constexpr double epsilon() { return 0.0011; }
 
+constexpr double min_delta_area() { return scale_(scale_(25)); } // equal to 25 mm2
+constexpr double min_threshold()  { return scale_(scale_(1)); }  // equal to 1 mm2
+
+bool possible_threshold(const double& bottom_area, const double& top_area);
+bool equivalent_areas(const double& bottom_area, const double& top_area);
+bool overhang(const double& bottom_area, const double& top_area);
+
 // custom message the slider sends to its parent to notify a tick-change:
 wxDECLARE_EVENT(wxCUSTOMEVT_TICKSCHANGED, wxEvent);
 

src/slic3r/GUI/GUI_Preview.cpp

@@ -687,7 +687,6 @@ void Preview::update_layers_slider(const std::vector<double>& layers_z, bool kee
     if (m_layers_slider->IsNewPrint())
     {
         const Print& print = wxGetApp().plater()->fff_print();
-        double delta_area = scale_(scale_(25)); // equal to 25 mm2
 
         //bool is_possible_auto_color_change = false;
         for (auto object : print.objects()) {
@@ -708,7 +707,7 @@ void Preview::update_layers_slider(const std::vector<double>& layers_z, bool kee
             int  i, min_solid_height = int(0.25 * num_layers);
             for (i = 1; i <= min_solid_height; ++ i) {
                 double cur_area = area(object->get_layer(i)->lslices);
-                if (cur_area != bottom_area && fabs(cur_area - bottom_area) > scale_(scale_(1))) {
+                if (!DoubleSlider::equivalent_areas(bottom_area, cur_area)) {
                     // but due to the elephant foot compensation, the first layer may be slightly smaller than the others
                     if (i == 1 && fabs(cur_area - bottom_area) / bottom_area < 0.1) {
                         // So, let process this case and use second layer as a bottom 
@@ -725,7 +724,7 @@ void Preview::update_layers_slider(const std::vector<double>& layers_z, bool kee
             double prev_area = area(object->get_layer(i)->lslices);
             for ( i++; i < num_layers; i++) {
                 double cur_area = area(object->get_layer(i)->lslices);
-                if (cur_area > prev_area && prev_area - cur_area > scale_(scale_(1)))
+                if (DoubleSlider::overhang(prev_area, cur_area))
                     break;
                 prev_area = cur_area;
             }
@@ -733,7 +732,7 @@ void Preview::update_layers_slider(const std::vector<double>& layers_z, bool kee
                 continue;
 
             double top_area = area(object->get_layer(int(object->layers().size()) - 1)->lslices);
-            if( bottom_area - top_area > delta_area) {
+            if (DoubleSlider::possible_threshold(bottom_area, top_area)) {
                 NotificationManager *notif_mngr = wxGetApp().plater()->get_notification_manager();
                 notif_mngr->push_notification(
                     NotificationType::SignDetected, NotificationManager::NotificationLevel::PrintInfoNotificationLevel,