PixelPaint: Set Tool on_*_color_change logic using virtual functions

Previously, we were rewriting the on_primary_color_change in the Text
Tool and Gradient, which made the palette widget no longer update after
picking a color from an image. Additionally, it also crashed the program
after leaving the Gradient tool and trying to change color.

Userland/Applications/PixelPaint/MainWidget.cpp

@@ -1229,6 +1229,17 @@ ImageEditor& MainWidget::create_new_editor(NonnullRefPtr<Image> image)
     },
         100);
 
+    image_editor.on_primary_color_change = [&](Color color) {
+        m_palette_widget->set_primary_color(color);
+        if (image_editor.active_tool())
+            image_editor.active_tool()->on_primary_color_change(color);
+    };
+    image_editor.on_secondary_color_change = [&](Color color) {
+        m_palette_widget->set_secondary_color(color);
+        if (image_editor.active_tool())
+            image_editor.active_tool()->on_secondary_color_change(color);
+    };
+
     if (image->layer_count())
         image_editor.set_active_layer(&image->layer(0));
 

Userland/Applications/PixelPaint/PaletteWidget.cpp

@@ -150,14 +150,6 @@ void PaletteWidget::set_image_editor(ImageEditor* editor)
 
     set_primary_color(editor->primary_color());
     set_secondary_color(editor->secondary_color());
-
-    editor->on_primary_color_change = [this](Color color) {
-        set_primary_color(color);
-    };
-
-    editor->on_secondary_color_change = [this](Color color) {
-        set_secondary_color(color);
-    };
 }
 
 void PaletteWidget::set_primary_color(Color color)

Userland/Applications/PixelPaint/Tools/GradientTool.cpp

@@ -163,13 +163,14 @@ void GradientTool::on_second_paint(Layer const* layer, GUI::PaintEvent& event)
     draw_gradient(painter, true, m_editor->content_to_frame_position(Gfx::IntPoint(0, 0)), m_editor->scale(), m_editor->content_rect());
 }
 
-void GradientTool::on_tool_activation()
+void GradientTool::on_primary_color_change(Color)
 {
-    m_editor->on_primary_color_change = [this](Color) {
-        if (m_gradient_end.has_value())
-            m_editor->update();
-    };
+    if (m_gradient_end.has_value())
+        m_editor->update();
+}
 
+void GradientTool::on_tool_activation()
+{
     reset();
 }
 

Userland/Applications/PixelPaint/Tools/GradientTool.h

@@ -20,6 +20,7 @@ public:
     virtual void on_mouseup(Layer*, MouseEvent&) override;
     virtual bool on_keydown(GUI::KeyEvent&) override;
     virtual void on_keyup(GUI::KeyEvent&) override;
+    virtual void on_primary_color_change(Color) override;
     virtual void on_tool_activation() override;
     virtual GUI::Widget* get_properties_widget() override;
 

Userland/Applications/PixelPaint/Tools/TextTool.cpp

@@ -41,11 +41,9 @@ TextTool::TextTool()
     }).release_value_but_fixme_should_propagate_errors();
 }
 
-void TextTool::on_tool_activation()
+void TextTool::on_primary_color_change(Color color)
 {
-    m_editor->on_primary_color_change = [this](auto color) {
-        m_text_color = color;
-    };
+    m_text_color = color;
 }
 
 void TextTool::on_tool_deactivation()

Userland/Applications/PixelPaint/Tools/TextTool.h

@@ -37,7 +37,7 @@ public:
     virtual void on_mousedown(Layer*, MouseEvent&) override;
     virtual bool on_keydown(GUI::KeyEvent&) override;
     virtual void on_second_paint(Layer const*, GUI::PaintEvent&) override;
-    virtual void on_tool_activation() override;
+    virtual void on_primary_color_change(Color) override;
     virtual void on_tool_deactivation() override;
     virtual Variant<Gfx::StandardCursor, NonnullRefPtr<Gfx::Bitmap>> cursor() override;
     virtual GUI::Widget* get_properties_widget() override;

Userland/Applications/PixelPaint/Tools/Tool.h

@@ -63,6 +63,8 @@ public:
     virtual void on_second_paint(Layer const*, GUI::PaintEvent&) { }
     virtual bool on_keydown(GUI::KeyEvent&);
     virtual void on_keyup(GUI::KeyEvent&) { }
+    virtual void on_primary_color_change(Color) { }
+    virtual void on_secondary_color_change(Color) { }
     virtual void on_tool_activation() { }
     virtual void on_tool_deactivation() { }
     virtual GUI::Widget* get_properties_widget() { return nullptr; }