PixelPaint: Add a Selection class (ImageEditor has a Selection)

This will represent a complex, region-based selection in the future.
For now though, it's just a simple rectangle. :^)

Userland/Applications/PixelPaint/CMakeLists.txt

@@ -21,6 +21,7 @@ set(SOURCES
     PixelPaintWindowGML.h
     RectangleTool.cpp
     RectangleSelectTool.cpp
+    Selection.cpp
     SprayTool.cpp
     ToolboxWidget.cpp
     ToolPropertiesWidget.cpp

Userland/Applications/PixelPaint/ImageEditor.cpp

@@ -95,6 +95,9 @@ void ImageEditor::paint_event(GUI::PaintEvent& event)
     if (m_active_layer) {
         painter.draw_rect(enclosing_int_rect(image_rect_to_editor_rect(m_active_layer->relative_rect())).inflated(2, 2), Color::Black);
     }
+
+    if (!m_selection.is_empty())
+        m_selection.paint(painter, *this);
 }
 
 Gfx::FloatRect ImageEditor::layer_rect_to_editor_rect(Layer const& layer, Gfx::IntRect const& layer_rect) const

Userland/Applications/PixelPaint/ImageEditor.h

@@ -7,6 +7,7 @@
 #pragma once
 
 #include "Image.h"
+#include "Selection.h"
 #include <LibGUI/Frame.h>
 #include <LibGUI/UndoStack.h>
 #include <LibGfx/Point.h>
@@ -53,6 +54,9 @@ public:
     Color secondary_color() const { return m_secondary_color; }
     void set_secondary_color(Color);
 
+    Selection& selection() { return m_selection; }
+    Selection const& selection() const { return m_selection; }
+
     Color color_for(GUI::MouseEvent const&) const;
     Color color_for(GUI::MouseButton) const;
 
@@ -105,6 +109,8 @@ private:
     Gfx::FloatPoint m_pan_origin;
     Gfx::FloatPoint m_saved_pan_origin;
     Gfx::IntPoint m_click_position;
+
+    Selection m_selection;
 };
 
 }

Userland/Applications/PixelPaint/RectangleSelectTool.cpp

@@ -58,6 +58,9 @@ void RectangleSelectTool::on_mouseup(Layer&, GUI::MouseEvent&, GUI::MouseEvent&
 
     m_selecting = false;
     m_editor->update();
+
+    auto rect_in_image = Gfx::IntRect::from_two_points(m_selection_start, m_selection_end);
+    m_editor->selection().set(rect_in_image);
 }
 
 void RectangleSelectTool::draw_marching_ants(Gfx::Painter& painter, Gfx::IntRect const& rect) const

Userland/Applications/PixelPaint/Selection.cpp

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "Selection.h"
+#include "ImageEditor.h"
+#include <LibGfx/Painter.h>
+
+namespace PixelPaint {
+
+void Selection::paint(Gfx::Painter& painter, ImageEditor const& editor)
+{
+    painter.draw_rect(editor.image_rect_to_editor_rect(m_rect).to_type<int>(), Color::Magenta);
+}
+
+}

Userland/Applications/PixelPaint/Selection.h

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibGfx/Rect.h>
+
+namespace PixelPaint {
+
+class ImageEditor;
+
+// Coordinates are image-relative.
+class Selection {
+public:
+    Selection() { }
+
+    bool is_empty() const { return m_rect.is_empty(); }
+    void clear() { m_rect = {}; }
+    void set(Gfx::IntRect const& rect) { m_rect = rect; }
+
+    void paint(Gfx::Painter&, ImageEditor const&);
+
+private:
+    Gfx::IntRect m_rect;
+};
+
+}