Fix of SPE-691 Slicer crash after extruder change

Added synchronization of GCodePreviewData between the front end / back end
(GCodePreview data is only used if PrintStep psGCodeExport is finished).
Added reset of GCodePreviewData on Print::apply() to conserve RAM.

src/libslic3r/Config.cpp

@@ -483,8 +483,9 @@ bool DynamicConfig::operator==(const DynamicConfig &rhs) const
     t_options_map::const_iterator it2     = rhs.options.begin();
     t_options_map::const_iterator it2_end = rhs.options.end();
     for (; it1 != it1_end && it2 != it2_end; ++ it1, ++ it2)
-        if (*it1->second != *it2->second)
-            return false;
+		if (it1->first != it2->first || *it1->second != *it2->second)
+			// key or value differ
+			return false;
     return it1 == it1_end && it2 == it2_end;
 }
 

src/libslic3r/GCode/Analyzer.cpp

@@ -668,6 +668,7 @@ void GCodeAnalyzer::_calc_gcode_preview_extrusion_layers(GCodePreviewData& previ
     {
         static GCodePreviewData::Extrusion::Layer& get_layer_at_z(GCodePreviewData::Extrusion::LayersList& layers, float z)
         {
+            //FIXME this has a terrible time complexity
             for (GCodePreviewData::Extrusion::Layer& layer : layers)
             {
                 // if layer found, return it
@@ -863,20 +864,4 @@ size_t GCodeAnalyzer::memory_used() const
     return out;
 }
 
-GCodePreviewData::Color operator + (const GCodePreviewData::Color& c1, const GCodePreviewData::Color& c2)
-{
-    return GCodePreviewData::Color(clamp(0.0f, 1.0f, c1.rgba[0] + c2.rgba[0]),
-        clamp(0.0f, 1.0f, c1.rgba[1] + c2.rgba[1]),
-        clamp(0.0f, 1.0f, c1.rgba[2] + c2.rgba[2]),
-        clamp(0.0f, 1.0f, c1.rgba[3] + c2.rgba[3]));
-}
-
-GCodePreviewData::Color operator * (float f, const GCodePreviewData::Color& color)
-{
-    return GCodePreviewData::Color(clamp(0.0f, 1.0f, f * color.rgba[0]),
-        clamp(0.0f, 1.0f, f * color.rgba[1]),
-        clamp(0.0f, 1.0f, f * color.rgba[2]),
-        clamp(0.0f, 1.0f, f * color.rgba[3]));
-}
-
 } // namespace Slic3r

src/libslic3r/GCode/PreviewData.cpp

@@ -521,4 +521,20 @@ size_t GCodePreviewData::memory_used() const
         sizeof(shell) + sizeof(ranges);
 }
 
+GCodePreviewData::Color operator + (const GCodePreviewData::Color& c1, const GCodePreviewData::Color& c2)
+{
+    return GCodePreviewData::Color(clamp(0.0f, 1.0f, c1.rgba[0] + c2.rgba[0]),
+        clamp(0.0f, 1.0f, c1.rgba[1] + c2.rgba[1]),
+        clamp(0.0f, 1.0f, c1.rgba[2] + c2.rgba[2]),
+        clamp(0.0f, 1.0f, c1.rgba[3] + c2.rgba[3]));
+}
+
+GCodePreviewData::Color operator * (float f, const GCodePreviewData::Color& color)
+{
+    return GCodePreviewData::Color(clamp(0.0f, 1.0f, f * color.rgba[0]),
+        clamp(0.0f, 1.0f, f * color.rgba[1]),
+        clamp(0.0f, 1.0f, f * color.rgba[2]),
+        clamp(0.0f, 1.0f, f * color.rgba[3]));
+}
+
 } // namespace Slic3r

src/libslic3r/GCode/PreviewData.hpp

@@ -22,6 +22,7 @@ public:
         static const Color Dummy;
     };
 
+    // Color mapping from a <min, max> range into a smooth rainbow of 10 colors.
     struct Range
     {
         static const unsigned int Colors_Count = 10;
@@ -45,9 +46,13 @@ public:
 
     struct Ranges
     {
+        // Color mapping by layer height.
         Range height;
+        // Color mapping by extrusion width.
         Range width;
+        // Color mapping by feedrate.
         Range feedrate;
+        // Color mapping by volumetric extrusion rate.
         Range volumetric_rate;
     };
 

src/slic3r/GUI/3DScene.hpp

@@ -18,7 +18,6 @@ class SLAPrintObject;
 enum  SLAPrintObjectStep : unsigned int;
 class Model;
 class ModelObject;
-class GCodePreviewData;
 class DynamicPrintConfig;
 class ExtrusionPath;
 class ExtrusionMultiPath;

src/slic3r/GUI/BackgroundSlicingProcess.cpp

@@ -15,8 +15,8 @@
 #include "libslic3r/SLAPrint.hpp"
 #include "libslic3r/Utils.hpp"
 #include "libslic3r/GCode/PostProcessor.hpp"
+#include "libslic3r/GCode/PreviewData.hpp"
 
-//#undef NDEBUG
 #include <cassert>
 #include <stdexcept>
 #include <cctype>
@@ -367,6 +367,13 @@ Print::ApplyStatus BackgroundSlicingProcess::apply(const Model &model, const Dyn
 	assert(m_print != nullptr);
 	assert(config.opt_enum<PrinterTechnology>("printer_technology") == m_print->technology());
 	Print::ApplyStatus invalidated = m_print->apply(model, config);
+	if ((invalidated & PrintBase::APPLY_STATUS_INVALIDATED) != 0 && m_print->technology() == ptFFF &&
+		m_gcode_preview_data != nullptr && ! this->m_fff_print->is_step_done(psGCodeExport)) {
+		// Some FFF status was invalidated, and the G-code was not exported yet.
+		// Let the G-code preview UI know that the final G-code preview is not valid.
+		// In addition, this early memory deallocation reduces memory footprint.
+		m_gcode_preview_data->reset();
+	}
 	return invalidated;
 }
 
@@ -392,7 +399,7 @@ void BackgroundSlicingProcess::schedule_upload(Slic3r::PrintHostJob upload_job)
 	// Guard against entering the export step before changing the export path.
 	tbb::mutex::scoped_lock lock(m_print->state_mutex());
 	this->invalidate_step(bspsGCodeFinalize);
-	m_export_path = std::string();
+	m_export_path.clear();
 	m_upload_job = std::move(upload_job);
 }
 

src/slic3r/GUI/GLCanvas3D.hpp

@@ -28,6 +28,7 @@ namespace Slic3r {
 class GLShader;
 class ExPolygon;
 class BackgroundSlicingProcess;
+class GCodePreviewData;
 
 namespace GUI {
 

src/slic3r/GUI/GLCanvas3DManager.hpp

@@ -19,7 +19,6 @@ class ExPolygon;
 typedef std::vector<ExPolygon> ExPolygons;
 class ModelObject;
 class PrintObject;
-class GCodePreviewData;
 
 namespace GUI {
 

src/slic3r/GUI/GUI.hpp

@@ -16,7 +16,6 @@ namespace Slic3r {
 class AppConfig;
 class DynamicPrintConfig;
 class Print;
-class GCodePreviewData;
 
 namespace GUI {
 

src/slic3r/GUI/GUI_Preview.cpp

@@ -395,12 +395,6 @@ void Preview::set_number_extruders(unsigned int number_extruders)
     }
 }
 
-void Preview::reset_gcode_preview_data()
-{
-    m_gcode_preview_data->reset();
-    m_canvas->reset_legend_texture();
-}
-
 void Preview::set_canvas_as_dirty()
 {
     m_canvas->set_as_dirty();
@@ -451,6 +445,7 @@ void Preview::load_print()
 void Preview::reload_print(bool force)
 {
     m_canvas->reset_volumes();
+    m_canvas->reset_legend_texture();
     m_loaded = false;
 
     if (!IsShown() && !force)
@@ -759,7 +754,8 @@ void Preview::load_print_as_fff()
 
     // Collect colors per extruder.
     std::vector<std::string> colors;
-    if (!m_gcode_preview_data->empty() || (m_gcode_preview_data->extrusion.view_type == GCodePreviewData::Extrusion::Tool))
+    bool gcode_preview_data_valid = print->is_step_done(psGCodeExport) && ! m_gcode_preview_data->empty();
+    if (gcode_preview_data_valid || (m_gcode_preview_data->extrusion.view_type == GCodePreviewData::Extrusion::Tool))
     {
         const ConfigOptionStrings* extruders_opt = dynamic_cast<const ConfigOptionStrings*>(m_config->option("extruder_colour"));
         const ConfigOptionStrings* filamemts_opt = dynamic_cast<const ConfigOptionStrings*>(m_config->option("filament_colour"));
@@ -785,13 +781,7 @@ void Preview::load_print_as_fff()
         // used to set the sliders to the extremes of the current zs range
         m_force_sliders_full_range = false;
 
-        if (m_gcode_preview_data->empty())
-        {
-            // load skirt and brim
-            m_canvas->load_preview(colors);
-            show_hide_ui_elements("simple");
-        }
-        else
+        if (gcode_preview_data_valid)
         {
             m_force_sliders_full_range = (m_canvas->get_volumes_count() == 0);
             m_canvas->load_gcode_preview(*m_gcode_preview_data, colors);
@@ -805,8 +795,15 @@ void Preview::load_print_as_fff()
                 reset_sliders();
                 m_canvas_widget->Refresh();
             }
+        } 
+        else
+        {
+            // load skirt and brim
+            m_canvas->load_preview(colors);
+            show_hide_ui_elements("simple");
         }
 
+
         if (n_layers > 0)
             update_sliders(m_canvas->get_current_print_zs(true));
 

src/slic3r/GUI/GUI_Preview.hpp

@@ -140,7 +140,6 @@ public:
 #endif // ENABLE_REMOVE_TABS_FROM_PLATER
 
     void set_number_extruders(unsigned int number_extruders);
-    void reset_gcode_preview_data();
     void set_canvas_as_dirty();
     void set_enabled(bool enabled);
     void set_bed_shape(const Pointfs& shape);

src/slic3r/GUI/Plater.cpp

@@ -1273,7 +1273,6 @@ void Plater::priv::update(bool force_full_scene_refresh)
 #else
     this->canvas3D->reload_scene(false, force_full_scene_refresh);
 #endif // ENABLE_REMOVE_TABS_FROM_PLATER
-    preview->reset_gcode_preview_data();
     preview->reload_print();
 
     this->schedule_background_process();
@@ -2010,7 +2009,6 @@ unsigned int Plater::priv::update_background_process()
         this->sidebar->show_sliced_info_sizer(false);
         // Reset preview canvases. If the print has been invalidated, the preview canvases will be cleared.
         // Otherwise they will be just refreshed.
-        this->gcode_preview_data.reset();
         switch (this->printer_technology) {
         case ptFFF:
             if (this->preview != nullptr)