PixelPaint: Include Guides in the ImageEditor

The ImageEditor knows about its Guides, how to draw them and exposes
ways to manipulate them.

Userland/Applications/PixelPaint/ImageEditor.cpp

@@ -83,6 +83,16 @@ void ImageEditor::paint_event(GUI::PaintEvent& event)
         painter.draw_rect(enclosing_int_rect(image_rect_to_editor_rect(m_active_layer->relative_rect())).inflated(2, 2), Color::Black);
     }
 
+    for (auto& guide : m_guides) {
+        if (guide.orientation() == Guide::Orientation::Horizontal) {
+            int y_coordinate = (int)image_position_to_editor_position({ 0.0f, guide.offset() }).y();
+            painter.draw_line({ 0, y_coordinate }, { rect().width(), y_coordinate }, Color::Cyan, 1, Gfx::Painter::LineStyle::Dashed, Color::LightGray);
+        } else if (guide.orientation() == Guide::Orientation::Vertical) {
+            int x_coordinate = (int)image_position_to_editor_position({ guide.offset(), 0.0f }).x();
+            painter.draw_line({ x_coordinate, 0 }, { x_coordinate, rect().height() }, Color::Cyan, 1, Gfx::Painter::LineStyle::Dashed, Color::LightGray);
+        }
+    }
+
     if (!m_selection.is_empty())
         m_selection.paint(painter);
 }
@@ -424,5 +434,4 @@ void ImageEditor::image_select_layer(Layer* layer)
 {
     set_active_layer(layer);
 }
-
 }

Userland/Applications/PixelPaint/ImageEditor.h

@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include "Guide.h"
 #include "Image.h"
 #include "Selection.h"
 #include <LibGUI/Frame.h>
@@ -38,6 +39,12 @@ public:
     bool undo();
     bool redo();
 
+    void add_guide(NonnullRefPtr<Guide> guide) { m_guides.append(guide); }
+    void remove_guide(Guide const& guide)
+    {
+        m_guides.remove_first_matching([&](auto& entry) { return &guide == entry.ptr(); });
+    }
+
     void layers_did_change();
 
     Layer* layer_at_editor_position(Gfx::IntPoint const&);
@@ -77,6 +84,8 @@ public:
     Gfx::FloatPoint image_position_to_editor_position(Gfx::IntPoint const&) const;
     Gfx::FloatPoint editor_position_to_image_position(Gfx::IntPoint const&) const;
 
+    NonnullRefPtrVector<Guide> const& guides() const { return m_guides; }
+
 private:
     explicit ImageEditor(NonnullRefPtr<Image>);
 
@@ -106,6 +115,8 @@ private:
     RefPtr<Layer> m_active_layer;
     OwnPtr<GUI::UndoStack> m_undo_stack;
 
+    NonnullRefPtrVector<Guide> m_guides;
+
     Tool* m_active_tool { nullptr };
 
     Color m_primary_color { Color::Black };