PaintBrush: Initial support for transparency. (#1883)

Applications/PaintBrush/BucketTool.cpp

@@ -55,9 +55,10 @@ static void flood_fill(Gfx::Bitmap& bitmap, const Gfx::Point& start_position, Co
     while (!queue.is_empty()) {
         auto position = queue.dequeue();
 
-        if (bitmap.get_pixel<Gfx::BitmapFormat::RGB32>(position.x(), position.y()) != target_color)
+        if (bitmap.get_pixel<Gfx::BitmapFormat::RGBA32>(position.x(), position.y()) != target_color)
             continue;
-        bitmap.set_pixel<Gfx::BitmapFormat::RGB32>(position.x(), position.y(), fill_color);
+        
+        bitmap.set_pixel<Gfx::BitmapFormat::RGBA32>(position.x(), position.y(), fill_color);
 
         if (position.x() != 0)
             queue.enqueue(position.translated(-1, 0));

Applications/PaintBrush/EraseTool.cpp

@@ -55,7 +55,7 @@ void EraseTool::on_mousedown(GUI::MouseEvent& event)
         return;
     Gfx::Rect r = build_rect(event.position(), m_widget->bitmap().rect());
     GUI::Painter painter(m_widget->bitmap());
-    painter.fill_rect(r, get_color());
+    painter.clear_rect(r, get_color());
     m_widget->update();
 }
 
@@ -67,7 +67,7 @@ void EraseTool::on_mousemove(GUI::MouseEvent& event)
     if (event.buttons() & GUI::MouseButton::Left || event.buttons() & GUI::MouseButton::Right) {
         Gfx::Rect r = build_rect(event.position(), m_widget->bitmap().rect());
         GUI::Painter painter(m_widget->bitmap());
-        painter.fill_rect(r, get_color());
+        painter.clear_rect(r, get_color());
         m_widget->update();
     }
 }
@@ -112,5 +112,5 @@ Color EraseTool::get_color() const
 {
     if (m_use_secondary_color)
         return m_widget->secondary_color();
-    return Color(Color::White);
+    return Color(255, 255, 255, 0);
 }

Applications/PaintBrush/EraseTool.h

@@ -27,8 +27,8 @@
 #pragma once
 
 #include "Tool.h"
-#include <LibGfx/Point.h>
 #include <LibGUI/ActionGroup.h>
+#include <LibGfx/Point.h>
 
 class EraseTool final : public Tool {
 public:
@@ -45,7 +45,7 @@ private:
     Gfx::Rect build_rect(const Gfx::Point& pos, const Gfx::Rect& widget_rect);
     RefPtr<GUI::Menu> m_context_menu;
 
-    bool m_use_secondary_color { true };
+    bool m_use_secondary_color { false };
     int m_thickness { 1 };
     GUI::ActionGroup m_thickness_actions;
 };

Applications/PaintBrush/PaintableWidget.cpp

@@ -26,9 +26,9 @@
 
 #include "PaintableWidget.h"
 #include "Tool.h"
+#include <LibGUI/Painter.h>
 #include <LibGfx/Bitmap.h>
 #include <LibGfx/Palette.h>
-#include <LibGUI/Painter.h>
 
 static PaintableWidget* s_the;
 
@@ -46,8 +46,8 @@ PaintableWidget::PaintableWidget()
     pal.set_color(ColorRole::Window, Color::MidGray);
     set_palette(pal);
     set_background_color(Color::MidGray);
-    m_bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::RGB32, { 600, 400 });
-    m_bitmap->fill(Color::White);
+    m_bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::RGBA32, { 600, 400 });
+    m_bitmap->fill(Color(255, 255, 255, 0));
 }
 
 PaintableWidget::~PaintableWidget()
@@ -57,7 +57,9 @@ PaintableWidget::~PaintableWidget()
 void PaintableWidget::paint_event(GUI::PaintEvent& event)
 {
     GUI::Painter painter(*this);
+
     painter.add_clip_rect(event.rect());
+    painter.fill_rect_with_checkerboard(m_bitmap->rect(), { 8, 8 }, palette().base().darkened(0.9), palette().base());
     painter.blit({ 0, 0 }, *m_bitmap, m_bitmap->rect());
 }