PixelPaint: Have layers and images send out notifications on changes

We use this to automatically update the thumbnail in LayerListWidget
when you draw into a layer. We also use it to repaint the ImageEditor
when the image changes somehow. :^)

14 files changed, 53 insertions, 12 deletions

diff --git a/Applications/PixelPaint/BucketTool.cpp b/Applications/PixelPaint/BucketTool.cpp
index 6b18fb4fc2..9795f5b440 100644
--- a/Applications/PixelPaint/BucketTool.cpp
+++ b/Applications/PixelPaint/BucketTool.cpp
@@ -87,7 +87,7 @@ void BucketTool::on_mousedown(Layer& layer, GUI::MouseEvent& event, GUI::MouseEv
 
     flood_fill(layer.bitmap(), event.position(), target_color, m_editor->color_for(event));
 
-    m_editor->update();
+    layer.did_modify_bitmap(*m_editor->image());
 }
 
 }
diff --git a/Applications/PixelPaint/EraseTool.cpp b/Applications/PixelPaint/EraseTool.cpp
index 4d91580f09..6efab8c13f 100644
--- a/Applications/PixelPaint/EraseTool.cpp
+++ b/Applications/PixelPaint/EraseTool.cpp
@@ -59,7 +59,7 @@ void EraseTool::on_mousedown(Layer& layer, GUI::MouseEvent& event, GUI::MouseEve
     Gfx::Rect r = build_rect(event.position(), layer.rect());
     GUI::Painter painter(layer.bitmap());
     painter.clear_rect(r, get_color());
-    m_editor->update();
+    layer.did_modify_bitmap(*m_editor->image());
 }
 
 void EraseTool::on_mousemove(Layer& layer, GUI::MouseEvent& event, GUI::MouseEvent&)
@@ -68,7 +68,7 @@ void EraseTool::on_mousemove(Layer& layer, GUI::MouseEvent& event, GUI::MouseEve
         Gfx::Rect r = build_rect(event.position(), layer.rect());
         GUI::Painter painter(layer.bitmap());
         painter.clear_rect(r, get_color());
-        m_editor->update();
+        layer.did_modify_bitmap(*m_editor->image());
     }
 }
 
diff --git a/Applications/PixelPaint/Image.cpp b/Applications/PixelPaint/Image.cpp
index e1a906df11..fa55c563d6 100644
--- a/Applications/PixelPaint/Image.cpp
+++ b/Applications/PixelPaint/Image.cpp
@@ -146,4 +146,19 @@ void Image::remove_client(ImageClient& client)
     m_clients.remove(&client);
 }
 
+void Image::layer_did_modify_bitmap(Badge<Layer>, const Layer& layer)
+{
+    auto layer_index = index_of(layer);
+    for (auto* client : m_clients)
+        client->image_did_modify_layer(layer_index);
+
+    did_change();
+}
+
+void Image::did_change()
+{
+    for (auto* client : m_clients)
+        client->image_did_change();
+}
+
 }
diff --git a/Applications/PixelPaint/Image.h b/Applications/PixelPaint/Image.h
index d8c0b86a58..56adb3a089 100644
--- a/Applications/PixelPaint/Image.h
+++ b/Applications/PixelPaint/Image.h
@@ -44,7 +44,8 @@ class ImageClient {
 public:
     virtual void image_did_add_layer(size_t) { }
     virtual void image_did_remove_layer(size_t) { }
-    virtual void image_did_update_layer(size_t) { }
+    virtual void image_did_modify_layer(size_t) { }
+    virtual void image_did_change() { }
 };
 
 class Image : public RefCounted<Image> {
@@ -72,9 +73,13 @@ public:
     void add_client(ImageClient&);
     void remove_client(ImageClient&);
 
+    void layer_did_modify_bitmap(Badge<Layer>, const Layer&);
+
 private:
     explicit Image(const Gfx::Size&);
 
+    void did_change();
+
     size_t index_of(const Layer&) const;
 
     Gfx::Size m_size;
diff --git a/Applications/PixelPaint/ImageEditor.cpp b/Applications/PixelPaint/ImageEditor.cpp
index 4d82ad0015..6a503d3bb3 100644
--- a/Applications/PixelPaint/ImageEditor.cpp
+++ b/Applications/PixelPaint/ImageEditor.cpp
@@ -353,4 +353,9 @@ void ImageEditor::relayout()
     update();
 }
 
+void ImageEditor::image_did_change()
+{
+    update();
+}
+
 }
diff --git a/Applications/PixelPaint/ImageEditor.h b/Applications/PixelPaint/ImageEditor.h
index e9f9b9c182..ce28d3b38e 100644
--- a/Applications/PixelPaint/ImageEditor.h
+++ b/Applications/PixelPaint/ImageEditor.h
@@ -26,16 +26,18 @@
 
 #pragma once
 
+#include "Image.h"
 #include <LibGUI/Frame.h>
 #include <LibGfx/FloatPoint.h>
 
 namespace PixelPaint {
 
-class Image;
 class Layer;
 class Tool;
 
-class ImageEditor final : public GUI::Frame {
+class ImageEditor final
+    : public GUI::Frame
+    , public ImageClient {
     C_OBJECT(ImageEditor);
 
 public:
@@ -91,6 +93,8 @@ private:
     virtual void context_menu_event(GUI::ContextMenuEvent&) override;
     virtual void resize_event(GUI::ResizeEvent&) override;
 
+    virtual void image_did_change() override;
+
     GUI::MouseEvent event_adjusted_for_layer(const GUI::MouseEvent&, const Layer&) const;
     GUI::MouseEvent event_with_pan_and_scale_applied(const GUI::MouseEvent&) const;
 
diff --git a/Applications/PixelPaint/Layer.cpp b/Applications/PixelPaint/Layer.cpp
index e633aaaf09..9c54eb7313 100644
--- a/Applications/PixelPaint/Layer.cpp
+++ b/Applications/PixelPaint/Layer.cpp
@@ -25,6 +25,7 @@
  */
 
 #include "Layer.h"
+#include "Image.h"
 #include <LibGfx/Bitmap.h>
 
 namespace PixelPaint {
@@ -46,4 +47,9 @@ Layer::Layer(const Gfx::Size& size, const String& name)
     m_bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::RGBA32, size);
 }
 
+void Layer::did_modify_bitmap(Image& image)
+{
+    image.layer_did_modify_bitmap({}, *this);
+}
+
 }
diff --git a/Applications/PixelPaint/Layer.h b/Applications/PixelPaint/Layer.h
index 5eb8ed2d12..cc192cbe3f 100644
--- a/Applications/PixelPaint/Layer.h
+++ b/Applications/PixelPaint/Layer.h
@@ -33,6 +33,8 @@
 
 namespace PixelPaint {
 
+class Image;
+
 class Layer : public RefCounted<Layer> {
     AK_MAKE_NONCOPYABLE(Layer);
     AK_MAKE_NONMOVABLE(Layer);
@@ -55,6 +57,8 @@ public:
     const String& name() const { return m_name; }
     void set_name(const String& name) { m_name = name; }
 
+    void did_modify_bitmap(Image&);
+
 private:
     explicit Layer(const Gfx::Size&, const String& name);
 
diff --git a/Applications/PixelPaint/LayerListWidget.cpp b/Applications/PixelPaint/LayerListWidget.cpp
index a819c911f4..42b14aee84 100644
--- a/Applications/PixelPaint/LayerListWidget.cpp
+++ b/Applications/PixelPaint/LayerListWidget.cpp
@@ -125,7 +125,7 @@ void LayerListWidget::image_did_remove_layer(size_t layer_index)
     relayout_gadgets();
 }
 
-void LayerListWidget::image_did_update_layer(size_t layer_index)
+void LayerListWidget::image_did_modify_layer(size_t layer_index)
 {
     update(m_gadgets[layer_index].rect);
 }
diff --git a/Applications/PixelPaint/LayerListWidget.h b/Applications/PixelPaint/LayerListWidget.h
index 1f24883526..a1f86dc37c 100644
--- a/Applications/PixelPaint/LayerListWidget.h
+++ b/Applications/PixelPaint/LayerListWidget.h
@@ -52,7 +52,7 @@ private:
 
     virtual void image_did_add_layer(size_t) override;
     virtual void image_did_remove_layer(size_t) override;
-    virtual void image_did_update_layer(size_t);
+    virtual void image_did_modify_layer(size_t);
 
     void relayout_gadgets();
 
diff --git a/Applications/PixelPaint/LineTool.cpp b/Applications/PixelPaint/LineTool.cpp
index 04b14b8a46..bffa6f11f1 100644
--- a/Applications/PixelPaint/LineTool.cpp
+++ b/Applications/PixelPaint/LineTool.cpp
@@ -77,7 +77,7 @@ void LineTool::on_mouseup(Layer& layer, GUI::MouseEvent& event, GUI::MouseEvent&
         GUI::Painter painter(layer.bitmap());
         painter.draw_line(m_line_start_position, m_line_end_position, m_editor->color_for(m_drawing_button), m_thickness);
         m_drawing_button = GUI::MouseButton::None;
-        m_editor->update();
+        layer.did_modify_bitmap(*m_editor->image());
     }
 }
 
diff --git a/Applications/PixelPaint/PenTool.cpp b/Applications/PixelPaint/PenTool.cpp
index bf50ed1b36..0f1b7d8814 100644
--- a/Applications/PixelPaint/PenTool.cpp
+++ b/Applications/PixelPaint/PenTool.cpp
@@ -48,7 +48,7 @@ void PenTool::on_mousedown(Layer& layer, GUI::MouseEvent& event, GUI::MouseEvent
 
     GUI::Painter painter(layer.bitmap());
     painter.draw_line(event.position(), event.position(), m_editor->color_for(event), m_thickness);
-    m_editor->update();
+    layer.did_modify_bitmap(*m_editor->image());
     m_last_drawing_event_position = event.position();
 }
 
@@ -68,7 +68,7 @@ void PenTool::on_mousemove(Layer& layer, GUI::MouseEvent& event, GUI::MouseEvent
         painter.draw_line(m_last_drawing_event_position, event.position(), m_editor->color_for(event), m_thickness);
     else
         painter.draw_line(event.position(), event.position(), m_editor->color_for(event), m_thickness);
-    m_editor->update();
+    layer.did_modify_bitmap(*m_editor->image());
 
     m_last_drawing_event_position = event.position();
 }
diff --git a/Applications/PixelPaint/RectangleTool.cpp b/Applications/PixelPaint/RectangleTool.cpp
index 2b238fa2d8..1207dc7888 100644
--- a/Applications/PixelPaint/RectangleTool.cpp
+++ b/Applications/PixelPaint/RectangleTool.cpp
@@ -81,7 +81,7 @@ void RectangleTool::on_mouseup(Layer& layer, GUI::MouseEvent& event, GUI::MouseE
         auto rect = Gfx::Rect::from_two_points(m_rectangle_start_position, m_rectangle_end_position);
         draw_using(painter, rect);
         m_drawing_button = GUI::MouseButton::None;
-        m_editor->update();
+        layer.did_modify_bitmap(*m_editor->image());
     }
 }
 
diff --git a/Applications/PixelPaint/SprayTool.cpp b/Applications/PixelPaint/SprayTool.cpp
index 36e92dbd85..0a685e36e0 100644
--- a/Applications/PixelPaint/SprayTool.cpp
+++ b/Applications/PixelPaint/SprayTool.cpp
@@ -79,6 +79,8 @@ void SprayTool::paint_it()
             continue;
         bitmap.set_pixel<Gfx::BitmapFormat::RGB32>(xpos, ypos, m_color);
     }
+
+    layer->did_modify_bitmap(*m_editor->image());
 }
 
 void SprayTool::on_mousedown(Layer&, GUI::MouseEvent& event, GUI::MouseEvent&)