PixelPaint: Draw the current editor selection as marching ants

This patch moves the marching ants painting code to Selection and
unifies the timer mechanism so that all marching ants are synchronized
which looks neat. :^)

Userland/Applications/PixelPaint/ImageEditor.cpp

@@ -20,6 +20,7 @@ namespace PixelPaint {
 
 ImageEditor::ImageEditor()
     : m_undo_stack(make<GUI::UndoStack>())
+    , m_selection(*this)
 {
     set_focus_policy(GUI::FocusPolicy::StrongFocus);
 }

Userland/Applications/PixelPaint/RectangleSelectTool.cpp

@@ -5,26 +5,14 @@
  */
 
 #include "RectangleSelectTool.h"
-#include "Image.h"
 #include "ImageEditor.h"
 #include "Layer.h"
-#include <LibCore/Timer.h>
 #include <LibGUI/Painter.h>
 
 namespace PixelPaint {
 
-constexpr int marching_ant_length = 4;
-
 RectangleSelectTool::RectangleSelectTool()
 {
-    m_marching_ants_timer = Core::Timer::create_repeating(80, [this] {
-        if (!m_editor)
-            return;
-        ++m_marching_ants_offset;
-        m_marching_ants_offset %= marching_ant_length;
-        m_editor->update();
-    });
-    m_marching_ants_timer->start();
 }
 
 RectangleSelectTool::~RectangleSelectTool()
@@ -63,33 +51,6 @@ void RectangleSelectTool::on_mouseup(Layer&, GUI::MouseEvent&, GUI::MouseEvent&
     m_editor->selection().set(rect_in_image);
 }
 
-void RectangleSelectTool::draw_marching_ants(Gfx::Painter& painter, Gfx::IntRect const& rect) const
-{
-    int offset = m_marching_ants_offset;
-
-    auto draw_pixel = [&](int x, int y) {
-        if ((offset % marching_ant_length) != 0)
-            painter.set_pixel(x, y, Color::Black);
-        offset++;
-    };
-
-    // Top line
-    for (int x = rect.left(); x <= rect.right(); ++x)
-        draw_pixel(x, rect.top());
-
-    // Right line
-    for (int y = rect.top() + 1; y <= rect.bottom(); ++y)
-        draw_pixel(rect.right(), y);
-
-    // Bottom line
-    for (int x = rect.right() - 1; x >= rect.left(); --x)
-        draw_pixel(x, rect.bottom());
-
-    // Left line
-    for (int y = rect.bottom() - 1; y > rect.top(); --y)
-        draw_pixel(rect.left(), y);
-}
-
 void RectangleSelectTool::on_second_paint(Layer const&, GUI::PaintEvent& event)
 {
     if (!m_selecting)
@@ -101,7 +62,7 @@ void RectangleSelectTool::on_second_paint(Layer const&, GUI::PaintEvent& event)
     auto rect_in_image = Gfx::IntRect::from_two_points(m_selection_start, m_selection_end);
     auto rect_in_editor = m_editor->image_rect_to_editor_rect(rect_in_image);
 
-    draw_marching_ants(painter, rect_in_editor.to_type<int>());
+    m_editor->selection().draw_marching_ants(painter, rect_in_editor.to_type<int>());
 }
 
 }

Userland/Applications/PixelPaint/RectangleSelectTool.h

@@ -21,13 +21,9 @@ public:
     virtual void on_second_paint(Layer const&, GUI::PaintEvent&) override;
 
 private:
-    void draw_marching_ants(Gfx::Painter&, Gfx::IntRect const&) const;
-
     bool m_selecting { false };
     Gfx::IntPoint m_selection_start;
     Gfx::IntPoint m_selection_end;
-    RefPtr<Core::Timer> m_marching_ants_timer;
-    int m_marching_ants_offset { 0 };
 };
 
 }

Userland/Applications/PixelPaint/Selection.cpp

@@ -10,9 +10,50 @@
 
 namespace PixelPaint {
 
+constexpr int marching_ant_length = 4;
+
 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);
+    draw_marching_ants(painter, editor.image_rect_to_editor_rect(m_rect).to_type<int>());
+}
+
+Selection::Selection(ImageEditor& editor)
+    : m_editor(editor)
+{
+    m_marching_ants_timer = Core::Timer::create_repeating(80, [this] {
+        ++m_marching_ants_offset;
+        m_marching_ants_offset %= marching_ant_length;
+        if (!is_empty())
+            m_editor.update();
+    });
+    m_marching_ants_timer->start();
+}
+
+void Selection::draw_marching_ants(Gfx::Painter& painter, Gfx::IntRect const& rect) const
+{
+    int offset = m_marching_ants_offset;
+
+    auto draw_pixel = [&](int x, int y) {
+        if ((offset % marching_ant_length) != 0)
+            painter.set_pixel(x, y, Color::Black);
+        offset++;
+    };
+
+    // Top line
+    for (int x = rect.left(); x <= rect.right(); ++x)
+        draw_pixel(x, rect.top());
+
+    // Right line
+    for (int y = rect.top() + 1; y <= rect.bottom(); ++y)
+        draw_pixel(rect.right(), y);
+
+    // Bottom line
+    for (int x = rect.right() - 1; x >= rect.left(); --x)
+        draw_pixel(x, rect.bottom());
+
+    // Left line
+    for (int y = rect.bottom() - 1; y > rect.top(); --y)
+        draw_pixel(rect.left(), y);
 }
 
 }

Userland/Applications/PixelPaint/Selection.h

@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <LibCore/Timer.h>
 #include <LibGfx/Rect.h>
 
 namespace PixelPaint {
@@ -15,7 +16,7 @@ class ImageEditor;
 // Coordinates are image-relative.
 class Selection {
 public:
-    Selection() { }
+    explicit Selection(ImageEditor&);
 
     bool is_empty() const { return m_rect.is_empty(); }
     void clear() { m_rect = {}; }
@@ -23,8 +24,13 @@ public:
 
     void paint(Gfx::Painter&, ImageEditor const&);
 
+    void draw_marching_ants(Gfx::Painter&, Gfx::IntRect const&) const;
+
 private:
+    ImageEditor& m_editor;
     Gfx::IntRect m_rect;
+    RefPtr<Core::Timer> m_marching_ants_timer;
+    int m_marching_ants_offset { 0 };
 };
 
 }