Add support to create palettes for Indexed images (fix #751)

src/app/commands/cmd_color_quantization.cpp

@@ -55,10 +55,9 @@ public:
 private:
 
   void onJob() override {
-    render::create_palette_from_rgb(m_sprite,
-                                    0, m_sprite->lastFrame(),
-                                    m_withAlpha, m_palette,
-                                    this);
+    render::create_palette_from_sprite(
+      m_sprite, 0, m_sprite->lastFrame(),
+      m_withAlpha, m_palette, this);
   }
 
   bool onPaletteOptimizerContinue() override {
@@ -83,9 +82,7 @@ ColorQuantizationCommand::ColorQuantizationCommand()
 
 bool ColorQuantizationCommand::onEnabled(Context* context)
 {
-  ContextWriter writer(context);
-  Sprite* sprite(writer.sprite());
-  return (sprite && sprite->pixelFormat() == IMAGE_RGB);
+  return context->checkFlags(ContextFlags::ActiveDocumentIsWritable);
 }
 
 void ColorQuantizationCommand::onExecute(Context* context)

src/app/file/file.cpp

@@ -739,7 +739,7 @@ void fop_post_load(FileOp* fop)
         sprite->getPalettes().size() <= 1 &&
         sprite->palette(frame_t(0))->isBlack()) {
       base::SharedPtr<Palette> palette(
-        render::create_palette_from_rgb(
+        render::create_palette_from_sprite(
           sprite, frame_t(0), sprite->lastFrame(), true,
           nullptr, nullptr));
 

src/app/ui/color_bar.cpp

@@ -369,7 +369,8 @@ void ColorBar::onFocusPaletteView()
 void ColorBar::onBeforeExecuteCommand(CommandExecutionEvent& ev)
 {
   if (ev.command()->id() == CommandId::SetPalette ||
-      ev.command()->id() == CommandId::LoadPalette)
+      ev.command()->id() == CommandId::LoadPalette ||
+      ev.command()->id() == CommandId::ColorQuantization)
     showRemap();
 }
 

src/render/quantization.cpp

@@ -33,7 +33,7 @@ namespace render {
 using namespace doc;
 using namespace gfx;
 
-Palette* create_palette_from_rgb(
+Palette* create_palette_from_sprite(
   const Sprite* sprite,
   frame_t fromFrame,
   frame_t toFrame,

src/render/quantization.h

@@ -44,7 +44,7 @@ namespace render {
   };
 
   // Creates a new palette suitable to quantize the given RGB sprite to Indexed color.
-  Palette* create_palette_from_rgb(
+  Palette* create_palette_from_sprite(
     const Sprite* sprite,
     frame_t fromFrame,
     frame_t toFrame,