PixelPaint: Make Layer passed to tools a pointer

Some tools (e.g. ZoomTool) doesn't need layer to work. This commit
makes mouse events fire even if there is no layer. This fixes
a bug that ZoomTool didn't work when there is no layers.

Userland/Applications/PixelPaint/BrushTool.cpp

@@ -25,8 +25,11 @@ BrushTool::~BrushTool()
 {
 }
 
-void BrushTool::on_mousedown(Layer& layer, MouseEvent& event)
+void BrushTool::on_mousedown(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (layer_event.button() != GUI::MouseButton::Left && layer_event.button() != GUI::MouseButton::Right)
         return;
@@ -34,28 +37,31 @@ void BrushTool::on_mousedown(Layer& layer, MouseEvent& event)
     const int first_draw_opacity = 10;
 
     for (int i = 0; i < first_draw_opacity; ++i)
-        draw_point(layer.bitmap(), m_editor->color_for(layer_event), layer_event.position());
+        draw_point(layer->bitmap(), m_editor->color_for(layer_event), layer_event.position());
 
-    layer.did_modify_bitmap(Gfx::IntRect::centered_on(layer_event.position(), Gfx::IntSize { m_size * 2, m_size * 2 }));
+    layer->did_modify_bitmap(Gfx::IntRect::centered_on(layer_event.position(), Gfx::IntSize { m_size * 2, m_size * 2 }));
     m_last_position = layer_event.position();
 }
 
-void BrushTool::on_mousemove(Layer& layer, MouseEvent& event)
+void BrushTool::on_mousemove(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (!(layer_event.buttons() & GUI::MouseButton::Left || layer_event.buttons() & GUI::MouseButton::Right))
         return;
 
-    draw_line(layer.bitmap(), m_editor->color_for(layer_event), m_last_position, layer_event.position());
+    draw_line(layer->bitmap(), m_editor->color_for(layer_event), m_last_position, layer_event.position());
 
     auto modified_rect = Gfx::IntRect::from_two_points(m_last_position, layer_event.position()).inflated(m_size * 2, m_size * 2);
 
-    layer.did_modify_bitmap(modified_rect);
+    layer->did_modify_bitmap(modified_rect);
     m_last_position = layer_event.position();
     m_was_drawing = true;
 }
 
-void BrushTool::on_mouseup(Layer&, MouseEvent&)
+void BrushTool::on_mouseup(Layer*, MouseEvent&)
 {
     if (m_was_drawing) {
         m_editor->did_complete_action();

Userland/Applications/PixelPaint/BrushTool.h

@@ -15,9 +15,9 @@ public:
     BrushTool();
     virtual ~BrushTool() override;
 
-    virtual void on_mousedown(Layer&, MouseEvent&) override;
-    virtual void on_mousemove(Layer&, MouseEvent&) override;
-    virtual void on_mouseup(Layer&, MouseEvent&) override;
+    virtual void on_mousedown(Layer*, MouseEvent&) override;
+    virtual void on_mousemove(Layer*, MouseEvent&) override;
+    virtual void on_mouseup(Layer*, MouseEvent&) override;
     virtual GUI::Widget* get_properties_widget() override;
     virtual Gfx::StandardCursor cursor() override { return Gfx::StandardCursor::Crosshair; }
 

Userland/Applications/PixelPaint/BucketTool.cpp

@@ -70,18 +70,21 @@ static void flood_fill(Gfx::Bitmap& bitmap, Gfx::IntPoint const& start_position,
     }
 }
 
-void BucketTool::on_mousedown(Layer& layer, MouseEvent& event)
+void BucketTool::on_mousedown(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
-    if (!layer.rect().contains(layer_event.position()))
+    if (!layer->rect().contains(layer_event.position()))
         return;
 
-    GUI::Painter painter(layer.bitmap());
-    auto target_color = layer.bitmap().get_pixel(layer_event.x(), layer_event.y());
+    GUI::Painter painter(layer->bitmap());
+    auto target_color = layer->bitmap().get_pixel(layer_event.x(), layer_event.y());
 
-    flood_fill(layer.bitmap(), layer_event.position(), target_color, m_editor->color_for(layer_event), m_threshold);
+    flood_fill(layer->bitmap(), layer_event.position(), target_color, m_editor->color_for(layer_event), m_threshold);
 
-    layer.did_modify_bitmap();
+    layer->did_modify_bitmap();
     m_editor->did_complete_action();
 }
 

Userland/Applications/PixelPaint/BucketTool.h

@@ -15,7 +15,7 @@ public:
     BucketTool();
     virtual ~BucketTool() override;
 
-    virtual void on_mousedown(Layer&, MouseEvent&) override;
+    virtual void on_mousedown(Layer*, MouseEvent&) override;
     virtual GUI::Widget* get_properties_widget() override;
 
 private:

Userland/Applications/PixelPaint/EllipseTool.cpp

@@ -40,8 +40,11 @@ void EllipseTool::draw_using(GUI::Painter& painter, Gfx::IntRect const& ellipse_
     }
 }
 
-void EllipseTool::on_mousedown(Layer&, MouseEvent& event)
+void EllipseTool::on_mousedown(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (layer_event.button() != GUI::MouseButton::Left && layer_event.button() != GUI::MouseButton::Right)
         return;
@@ -55,10 +58,13 @@ void EllipseTool::on_mousedown(Layer&, MouseEvent& event)
     m_editor->update();
 }
 
-void EllipseTool::on_mouseup(Layer& layer, MouseEvent& event)
+void EllipseTool::on_mouseup(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     if (event.layer_event().button() == m_drawing_button) {
-        GUI::Painter painter(layer.bitmap());
+        GUI::Painter painter(layer->bitmap());
         draw_using(painter, Gfx::IntRect::from_two_points(m_ellipse_start_position, m_ellipse_end_position));
         m_drawing_button = GUI::MouseButton::None;
         m_editor->update();
@@ -66,7 +72,7 @@ void EllipseTool::on_mouseup(Layer& layer, MouseEvent& event)
     }
 }
 
-void EllipseTool::on_mousemove(Layer&, MouseEvent& event)
+void EllipseTool::on_mousemove(Layer*, MouseEvent& event)
 {
     if (m_drawing_button == GUI::MouseButton::None)
         return;
@@ -75,15 +81,15 @@ void EllipseTool::on_mousemove(Layer&, MouseEvent& event)
     m_editor->update();
 }
 
-void EllipseTool::on_second_paint(Layer const& layer, GUI::PaintEvent& event)
+void EllipseTool::on_second_paint(Layer const* layer, GUI::PaintEvent& event)
 {
-    if (m_drawing_button == GUI::MouseButton::None)
+    if (!layer || m_drawing_button == GUI::MouseButton::None)
         return;
 
     GUI::Painter painter(*m_editor);
     painter.add_clip_rect(event.rect());
-    auto preview_start = m_editor->layer_position_to_editor_position(layer, m_ellipse_start_position).to_type<int>();
-    auto preview_end = m_editor->layer_position_to_editor_position(layer, m_ellipse_end_position).to_type<int>();
+    auto preview_start = m_editor->layer_position_to_editor_position(*layer, m_ellipse_start_position).to_type<int>();
+    auto preview_end = m_editor->layer_position_to_editor_position(*layer, m_ellipse_end_position).to_type<int>();
     draw_using(painter, Gfx::IntRect::from_two_points(preview_start, preview_end));
 }
 

Userland/Applications/PixelPaint/EllipseTool.h

@@ -17,10 +17,10 @@ public:
     EllipseTool();
     virtual ~EllipseTool() override;
 
-    virtual void on_mousedown(Layer&, MouseEvent&) override;
-    virtual void on_mousemove(Layer&, MouseEvent&) override;
-    virtual void on_mouseup(Layer&, MouseEvent&) override;
-    virtual void on_second_paint(Layer const&, GUI::PaintEvent&) override;
+    virtual void on_mousedown(Layer*, MouseEvent&) override;
+    virtual void on_mousemove(Layer*, MouseEvent&) override;
+    virtual void on_mouseup(Layer*, MouseEvent&) override;
+    virtual void on_second_paint(Layer const*, GUI::PaintEvent&) override;
     virtual void on_keydown(GUI::KeyEvent&) override;
     virtual GUI::Widget* get_properties_widget() override;
     virtual Gfx::StandardCursor cursor() override { return Gfx::StandardCursor::Crosshair; }

Userland/Applications/PixelPaint/EraseTool.cpp

@@ -35,30 +35,39 @@ Gfx::IntRect EraseTool::build_rect(Gfx::IntPoint const& pos, Gfx::IntRect const&
     return Gfx::IntRect(ex - eraser_radius, ey - eraser_radius, eraser_size, eraser_size).intersected(widget_rect);
 }
 
-void EraseTool::on_mousedown(Layer& layer, MouseEvent& event)
+void EraseTool::on_mousedown(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (layer_event.button() != GUI::MouseButton::Left && layer_event.button() != GUI::MouseButton::Right)
         return;
-    Gfx::IntRect r = build_rect(layer_event.position(), layer.rect());
-    GUI::Painter painter(layer.bitmap());
+    Gfx::IntRect r = build_rect(layer_event.position(), layer->rect());
+    GUI::Painter painter(layer->bitmap());
     painter.clear_rect(r, get_color());
-    layer.did_modify_bitmap(r.inflated(2, 2));
+    layer->did_modify_bitmap(r.inflated(2, 2));
 }
 
-void EraseTool::on_mousemove(Layer& layer, MouseEvent& event)
+void EraseTool::on_mousemove(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (layer_event.buttons() & GUI::MouseButton::Left || layer_event.buttons() & GUI::MouseButton::Right) {
-        Gfx::IntRect r = build_rect(layer_event.position(), layer.rect());
-        GUI::Painter painter(layer.bitmap());
+        Gfx::IntRect r = build_rect(layer_event.position(), layer->rect());
+        GUI::Painter painter(layer->bitmap());
         painter.clear_rect(r, get_color());
-        layer.did_modify_bitmap(r.inflated(2, 2));
+        layer->did_modify_bitmap(r.inflated(2, 2));
     }
 }
 
-void EraseTool::on_mouseup(Layer&, MouseEvent& event)
+void EraseTool::on_mouseup(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (layer_event.button() != GUI::MouseButton::Left && layer_event.button() != GUI::MouseButton::Right)
         return;

Userland/Applications/PixelPaint/EraseTool.h

@@ -18,9 +18,9 @@ public:
     EraseTool();
     virtual ~EraseTool() override;
 
-    virtual void on_mousedown(Layer&, MouseEvent& event) override;
-    virtual void on_mousemove(Layer&, MouseEvent& event) override;
-    virtual void on_mouseup(Layer&, MouseEvent& event) override;
+    virtual void on_mousedown(Layer*, MouseEvent& event) override;
+    virtual void on_mousemove(Layer*, MouseEvent& event) override;
+    virtual void on_mouseup(Layer*, MouseEvent& event) override;
     virtual GUI::Widget* get_properties_widget() override;
 
 private:

Userland/Applications/PixelPaint/GuideTool.cpp

@@ -49,7 +49,7 @@ RefPtr<Guide> GuideTool::closest_guide(const Gfx::IntPoint& point)
     return nullptr;
 }
 
-void GuideTool::on_mousedown(Layer&, MouseEvent& event)
+void GuideTool::on_mousedown(Layer*, MouseEvent& event)
 {
     if (!m_editor)
         return;
@@ -85,7 +85,7 @@ void GuideTool::on_mousedown(Layer&, MouseEvent& event)
     }
 }
 
-void GuideTool::on_mouseup(Layer&, MouseEvent&)
+void GuideTool::on_mouseup(Layer*, MouseEvent&)
 {
     m_guide_origin = 0;
     m_event_origin = { 0, 0 };
@@ -104,7 +104,7 @@ void GuideTool::on_mouseup(Layer&, MouseEvent&)
     m_selected_guide = nullptr;
 }
 
-void GuideTool::on_mousemove(Layer&, MouseEvent& event)
+void GuideTool::on_mousemove(Layer*, MouseEvent& event)
 {
     if (!m_selected_guide)
         return;
@@ -132,7 +132,7 @@ void GuideTool::on_mousemove(Layer&, MouseEvent& event)
     editor()->layers_did_change();
 }
 
-void GuideTool::on_context_menu(Layer&, GUI::ContextMenuEvent& event)
+void GuideTool::on_context_menu(Layer*, GUI::ContextMenuEvent& event)
 {
     if (!m_editor)
         return;

Userland/Applications/PixelPaint/GuideTool.h

@@ -18,10 +18,10 @@ public:
 
     virtual ~GuideTool() override;
 
-    virtual void on_mousedown(Layer&, MouseEvent&) override;
-    virtual void on_mousemove(Layer&, MouseEvent&) override;
-    virtual void on_mouseup(Layer&, MouseEvent&) override;
-    virtual void on_context_menu(Layer&, GUI::ContextMenuEvent&) override;
+    virtual void on_mousedown(Layer*, MouseEvent&) override;
+    virtual void on_mousemove(Layer*, MouseEvent&) override;
+    virtual void on_mouseup(Layer*, MouseEvent&) override;
+    virtual void on_context_menu(Layer*, GUI::ContextMenuEvent&) override;
 
     virtual void on_tool_activation() override;
 

Userland/Applications/PixelPaint/ImageEditor.cpp

@@ -145,8 +145,8 @@ Gfx::FloatPoint ImageEditor::editor_position_to_image_position(Gfx::IntPoint con
 
 void ImageEditor::second_paint_event(GUI::PaintEvent& event)
 {
-    if (m_active_tool && m_active_layer)
-        m_active_tool->on_second_paint(*m_active_layer, event);
+    if (m_active_tool)
+        m_active_tool->on_second_paint(m_active_layer, event);
 }
 
 GUI::MouseEvent ImageEditor::event_with_pan_and_scale_applied(GUI::MouseEvent const& event) const
@@ -194,13 +194,10 @@ void ImageEditor::mousedown_event(GUI::MouseEvent& event)
         }
     }
 
-    if (!m_active_layer)
-        return;
-
-    auto layer_event = event_adjusted_for_layer(event, *m_active_layer);
+    auto layer_event = m_active_layer ? event_adjusted_for_layer(event, *m_active_layer) : event;
     auto image_event = event_with_pan_and_scale_applied(event);
     Tool::MouseEvent tool_event(Tool::MouseEvent::Action::MouseDown, layer_event, image_event, event);
-    m_active_tool->on_mousedown(*m_active_layer, tool_event);
+    m_active_tool->on_mousedown(m_active_layer.ptr(), tool_event);
 }
 
 void ImageEditor::mousemove_event(GUI::MouseEvent& event)
@@ -215,13 +212,13 @@ void ImageEditor::mousemove_event(GUI::MouseEvent& event)
         return;
     }
 
-    if (!m_active_layer || !m_active_tool)
+    if (!m_active_tool)
         return;
 
-    auto layer_event = event_adjusted_for_layer(event, *m_active_layer);
+    auto layer_event = m_active_layer ? event_adjusted_for_layer(event, *m_active_layer) : event;
     auto image_event = event_with_pan_and_scale_applied(event);
     Tool::MouseEvent tool_event(Tool::MouseEvent::Action::MouseDown, layer_event, image_event, event);
-    m_active_tool->on_mousemove(*m_active_layer, tool_event);
+    m_active_tool->on_mousemove(m_active_layer.ptr(), tool_event);
 
     if (on_image_mouse_position_change) {
         on_image_mouse_position_change(image_event.position());
@@ -232,12 +229,12 @@ void ImageEditor::mouseup_event(GUI::MouseEvent& event)
 {
     set_override_cursor(m_active_cursor);
 
-    if (!m_active_layer || !m_active_tool)
+    if (!m_active_tool)
         return;
-    auto layer_event = event_adjusted_for_layer(event, *m_active_layer);
+    auto layer_event = m_active_layer ? event_adjusted_for_layer(event, *m_active_layer) : event;
     auto image_event = event_with_pan_and_scale_applied(event);
     Tool::MouseEvent tool_event(Tool::MouseEvent::Action::MouseDown, layer_event, image_event, event);
-    m_active_tool->on_mouseup(*m_active_layer, tool_event);
+    m_active_tool->on_mouseup(m_active_layer.ptr(), tool_event);
 }
 
 void ImageEditor::mousewheel_event(GUI::MouseEvent& event)
@@ -248,9 +245,9 @@ void ImageEditor::mousewheel_event(GUI::MouseEvent& event)
 
 void ImageEditor::context_menu_event(GUI::ContextMenuEvent& event)
 {
-    if (!m_active_layer || !m_active_tool)
+    if (!m_active_tool)
         return;
-    m_active_tool->on_context_menu(*m_active_layer, event);
+    m_active_tool->on_context_menu(m_active_layer, event);
 }
 
 void ImageEditor::resize_event(GUI::ResizeEvent& event)

Userland/Applications/PixelPaint/LineTool.cpp

@@ -38,8 +38,11 @@ LineTool::~LineTool()
 {
 }
 
-void LineTool::on_mousedown(Layer&, MouseEvent& event)
+void LineTool::on_mousedown(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (layer_event.button() != GUI::MouseButton::Left && layer_event.button() != GUI::MouseButton::Right)
         return;
@@ -55,20 +58,26 @@ void LineTool::on_mousedown(Layer&, MouseEvent& event)
     m_editor->update();
 }
 
-void LineTool::on_mouseup(Layer& layer, MouseEvent& event)
+void LineTool::on_mouseup(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (layer_event.button() == m_drawing_button) {
-        GUI::Painter painter(layer.bitmap());
+        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;
-        layer.did_modify_bitmap();
+        layer->did_modify_bitmap();
         m_editor->did_complete_action();
     }
 }
 
-void LineTool::on_mousemove(Layer&, MouseEvent& event)
+void LineTool::on_mousemove(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (m_drawing_button == GUI::MouseButton::None)
         return;
@@ -82,15 +91,15 @@ void LineTool::on_mousemove(Layer&, MouseEvent& event)
     m_editor->update();
 }
 
-void LineTool::on_second_paint(Layer const& layer, GUI::PaintEvent& event)
+void LineTool::on_second_paint(Layer const* layer, GUI::PaintEvent& event)
 {
-    if (m_drawing_button == GUI::MouseButton::None)
+    if (!layer || m_drawing_button == GUI::MouseButton::None)
         return;
 
     GUI::Painter painter(*m_editor);
     painter.add_clip_rect(event.rect());
-    auto preview_start = m_editor->layer_position_to_editor_position(layer, m_line_start_position).to_type<int>();
-    auto preview_end = m_editor->layer_position_to_editor_position(layer, m_line_end_position).to_type<int>();
+    auto preview_start = m_editor->layer_position_to_editor_position(*layer, m_line_start_position).to_type<int>();
+    auto preview_end = m_editor->layer_position_to_editor_position(*layer, m_line_end_position).to_type<int>();
     painter.draw_line(preview_start, preview_end, m_editor->color_for(m_drawing_button), m_thickness);
 }
 

Userland/Applications/PixelPaint/LineTool.h

@@ -17,10 +17,10 @@ public:
     LineTool();
     virtual ~LineTool() override;
 
-    virtual void on_mousedown(Layer&, MouseEvent&) override;
-    virtual void on_mousemove(Layer&, MouseEvent&) override;
-    virtual void on_mouseup(Layer&, MouseEvent&) override;
-    virtual void on_second_paint(Layer const&, GUI::PaintEvent&) override;
+    virtual void on_mousedown(Layer*, MouseEvent&) override;
+    virtual void on_mousemove(Layer*, MouseEvent&) override;
+    virtual void on_mouseup(Layer*, MouseEvent&) override;
+    virtual void on_second_paint(Layer const*, GUI::PaintEvent&) override;
     virtual void on_keydown(GUI::KeyEvent&) override;
     virtual GUI::Widget* get_properties_widget() override;
     virtual Gfx::StandardCursor cursor() override { return Gfx::StandardCursor::Crosshair; }

Userland/Applications/PixelPaint/MoveTool.cpp

@@ -23,21 +23,27 @@ MoveTool::~MoveTool()
 {
 }
 
-void MoveTool::on_mousedown(Layer& layer, MouseEvent& event)
+void MoveTool::on_mousedown(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     auto& image_event = event.image_event();
     if (layer_event.button() != GUI::MouseButton::Left)
         return;
-    if (!layer.rect().contains(layer_event.position()))
+    if (!layer->rect().contains(layer_event.position()))
         return;
-    m_layer_being_moved = layer;
+    m_layer_being_moved = *layer;
     m_event_origin = image_event.position();
-    m_layer_origin = layer.location();
+    m_layer_origin = layer->location();
 }
 
-void MoveTool::on_mousemove(Layer&, MouseEvent& event)
+void MoveTool::on_mousemove(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& image_event = event.image_event();
     if (!m_layer_being_moved)
         return;
@@ -46,8 +52,11 @@ void MoveTool::on_mousemove(Layer&, MouseEvent& event)
     m_editor->layers_did_change();
 }
 
-void MoveTool::on_mouseup(Layer&, MouseEvent& event)
+void MoveTool::on_mouseup(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (layer_event.button() != GUI::MouseButton::Left)
         return;

Userland/Applications/PixelPaint/MoveTool.h

@@ -15,9 +15,9 @@ public:
     MoveTool();
     virtual ~MoveTool() override;
 
-    virtual void on_mousedown(Layer&, MouseEvent&) override;
-    virtual void on_mousemove(Layer&, MouseEvent&) override;
-    virtual void on_mouseup(Layer&, MouseEvent&) override;
+    virtual void on_mousedown(Layer*, MouseEvent&) override;
+    virtual void on_mousemove(Layer*, MouseEvent&) override;
+    virtual void on_mouseup(Layer*, MouseEvent&) override;
     virtual void on_keydown(GUI::KeyEvent&) override;
     virtual Gfx::StandardCursor cursor() override { return Gfx::StandardCursor::Move; }
 

Userland/Applications/PixelPaint/PenTool.cpp

@@ -24,20 +24,26 @@ PenTool::~PenTool()
 {
 }
 
-void PenTool::on_mousedown(Layer& layer, MouseEvent& event)
+void PenTool::on_mousedown(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (layer_event.button() != GUI::MouseButton::Left && layer_event.button() != GUI::MouseButton::Right)
         return;
 
-    GUI::Painter painter(layer.bitmap());
+    GUI::Painter painter(layer->bitmap());
     painter.draw_line(layer_event.position(), layer_event.position(), m_editor->color_for(layer_event), m_thickness);
-    layer.did_modify_bitmap(Gfx::IntRect::centered_on(layer_event.position(), Gfx::IntSize { m_thickness + 2, m_thickness + 2 }));
+    layer->did_modify_bitmap(Gfx::IntRect::centered_on(layer_event.position(), Gfx::IntSize { m_thickness + 2, m_thickness + 2 }));
     m_last_drawing_event_position = layer_event.position();
 }
 
-void PenTool::on_mouseup(Layer&, MouseEvent& event)
+void PenTool::on_mouseup(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (layer_event.button() == GUI::MouseButton::Left || layer_event.button() == GUI::MouseButton::Right) {
         m_last_drawing_event_position = { -1, -1 };
@@ -45,12 +51,15 @@ void PenTool::on_mouseup(Layer&, MouseEvent& event)
     }
 }
 
-void PenTool::on_mousemove(Layer& layer, MouseEvent& event)
+void PenTool::on_mousemove(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (!(layer_event.buttons() & GUI::MouseButton::Left || layer_event.buttons() & GUI::MouseButton::Right))
         return;
-    GUI::Painter painter(layer.bitmap());
+    GUI::Painter painter(layer->bitmap());
 
     Gfx::IntRect changed_rect;
     if (m_last_drawing_event_position != Gfx::IntPoint(-1, -1)) {
@@ -61,7 +70,7 @@ void PenTool::on_mousemove(Layer& layer, MouseEvent& event)
         changed_rect = Gfx::IntRect::from_two_points(layer_event.position(), layer_event.position());
     }
     changed_rect.inflate(m_thickness + 2, m_thickness + 2);
-    layer.did_modify_bitmap(changed_rect);
+    layer->did_modify_bitmap(changed_rect);
 
     m_last_drawing_event_position = layer_event.position();
 }

Userland/Applications/PixelPaint/PenTool.h

@@ -17,9 +17,9 @@ public:
     PenTool();
     virtual ~PenTool() override;
 
-    virtual void on_mousedown(Layer&, MouseEvent&) override;
-    virtual void on_mousemove(Layer&, MouseEvent&) override;
-    virtual void on_mouseup(Layer&, MouseEvent&) override;
+    virtual void on_mousedown(Layer*, MouseEvent&) override;
+    virtual void on_mousemove(Layer*, MouseEvent&) override;
+    virtual void on_mouseup(Layer*, MouseEvent&) override;
     virtual GUI::Widget* get_properties_widget() override;
     virtual Gfx::StandardCursor cursor() override { return Gfx::StandardCursor::Crosshair; }
 

Userland/Applications/PixelPaint/PickerTool.cpp

@@ -18,12 +18,15 @@ PickerTool::~PickerTool()
 {
 }
 
-void PickerTool::on_mousedown(Layer& layer, MouseEvent& event)
+void PickerTool::on_mousedown(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
-    if (!layer.rect().contains(layer_event.position()))
+    if (!layer->rect().contains(layer_event.position()))
         return;
-    auto color = layer.bitmap().get_pixel(layer_event.position());
+    auto color = layer->bitmap().get_pixel(layer_event.position());
     if (layer_event.button() == GUI::MouseButton::Left)
         m_editor->set_primary_color(color);
     else if (layer_event.button() == GUI::MouseButton::Right)

Userland/Applications/PixelPaint/PickerTool.h

@@ -15,7 +15,7 @@ public:
     PickerTool();
     virtual ~PickerTool() override;
 
-    virtual void on_mousedown(Layer&, MouseEvent&) override;
+    virtual void on_mousedown(Layer*, MouseEvent&) override;
     virtual Gfx::StandardCursor cursor() override { return Gfx::StandardCursor::Crosshair; }
 };
 

Userland/Applications/PixelPaint/RectangleSelectTool.cpp

@@ -26,7 +26,7 @@ RectangleSelectTool::~RectangleSelectTool()
 {
 }
 
-void RectangleSelectTool::on_mousedown(Layer&, MouseEvent& event)
+void RectangleSelectTool::on_mousedown(Layer*, MouseEvent& event)
 {
     auto& image_event = event.image_event();
     if (image_event.button() != GUI::MouseButton::Left)
@@ -40,7 +40,7 @@ void RectangleSelectTool::on_mousedown(Layer&, MouseEvent& event)
     m_editor->update();
 }
 
-void RectangleSelectTool::on_mousemove(Layer&, MouseEvent& event)
+void RectangleSelectTool::on_mousemove(Layer*, MouseEvent& event)
 {
     auto& image_event = event.image_event();
     if (!m_selecting)
@@ -58,7 +58,7 @@ void RectangleSelectTool::on_mousemove(Layer&, MouseEvent& event)
     m_editor->update();
 }
 
-void RectangleSelectTool::on_mouseup(Layer&, MouseEvent& event)
+void RectangleSelectTool::on_mouseup(Layer*, MouseEvent& event)
 {
     auto& image_event = event.image_event();
     if (!m_selecting || image_event.button() != GUI::MouseButton::Left)
@@ -124,7 +124,7 @@ void RectangleSelectTool::on_keyup(GUI::KeyEvent& key_event)
         m_moving_mode = MovingMode::None;
 }
 
-void RectangleSelectTool::on_second_paint(Layer const&, GUI::PaintEvent& event)
+void RectangleSelectTool::on_second_paint(Layer const*, GUI::PaintEvent& event)
 {
     if (!m_selecting)
         return;

Userland/Applications/PixelPaint/RectangleSelectTool.h

@@ -19,12 +19,12 @@ public:
     RectangleSelectTool();
     virtual ~RectangleSelectTool();
 
-    virtual void on_mousedown(Layer&, MouseEvent& event) override;
-    virtual void on_mousemove(Layer&, MouseEvent& event) override;
-    virtual void on_mouseup(Layer&, MouseEvent& event) override;
+    virtual void on_mousedown(Layer*, MouseEvent& event) override;
+    virtual void on_mousemove(Layer*, MouseEvent& event) override;
+    virtual void on_mouseup(Layer*, MouseEvent& event) override;
     virtual void on_keydown(GUI::KeyEvent&) override;
     virtual void on_keyup(GUI::KeyEvent&) override;
-    virtual void on_second_paint(Layer const&, GUI::PaintEvent&) override;
+    virtual void on_second_paint(Layer const*, GUI::PaintEvent&) override;
     virtual GUI::Widget* get_properties_widget() override;
     virtual Gfx::StandardCursor cursor() override { return Gfx::StandardCursor::Crosshair; }
 

Userland/Applications/PixelPaint/RectangleTool.cpp

@@ -42,8 +42,11 @@ void RectangleTool::draw_using(GUI::Painter& painter, Gfx::IntRect const& rect)
     }
 }
 
-void RectangleTool::on_mousedown(Layer&, MouseEvent& event)
+void RectangleTool::on_mousedown(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     if (layer_event.button() != GUI::MouseButton::Left && layer_event.button() != GUI::MouseButton::Right)
         return;
@@ -57,20 +60,26 @@ void RectangleTool::on_mousedown(Layer&, MouseEvent& event)
     m_editor->update();
 }
 
-void RectangleTool::on_mouseup(Layer& layer, MouseEvent& event)
+void RectangleTool::on_mouseup(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     if (event.layer_event().button() == m_drawing_button) {
-        GUI::Painter painter(layer.bitmap());
+        GUI::Painter painter(layer->bitmap());
         auto rect = Gfx::IntRect::from_two_points(m_rectangle_start_position, m_rectangle_end_position);
         draw_using(painter, rect);
         m_drawing_button = GUI::MouseButton::None;
-        layer.did_modify_bitmap();
+        layer->did_modify_bitmap();
         m_editor->did_complete_action();
     }
 }
 
-void RectangleTool::on_mousemove(Layer&, MouseEvent& event)
+void RectangleTool::on_mousemove(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     if (m_drawing_button == GUI::MouseButton::None)
         return;
 
@@ -78,16 +87,16 @@ void RectangleTool::on_mousemove(Layer&, MouseEvent& event)
     m_editor->update();
 }
 
-void RectangleTool::on_second_paint(Layer const& layer, GUI::PaintEvent& event)
+void RectangleTool::on_second_paint(Layer const* layer, GUI::PaintEvent& event)
 {
-    if (m_drawing_button == GUI::MouseButton::None)
+    if (!layer || m_drawing_button == GUI::MouseButton::None)
         return;
 
     GUI::Painter painter(*m_editor);
     painter.add_clip_rect(event.rect());
     auto rect = Gfx::IntRect::from_two_points(
-        m_editor->layer_position_to_editor_position(layer, m_rectangle_start_position).to_type<int>(),
-        m_editor->layer_position_to_editor_position(layer, m_rectangle_end_position).to_type<int>());
+        m_editor->layer_position_to_editor_position(*layer, m_rectangle_start_position).to_type<int>(),
+        m_editor->layer_position_to_editor_position(*layer, m_rectangle_end_position).to_type<int>());
     draw_using(painter, rect);
 }
 

Userland/Applications/PixelPaint/RectangleTool.h

@@ -17,10 +17,10 @@ public:
     RectangleTool();
     virtual ~RectangleTool() override;
 
-    virtual void on_mousedown(Layer&, MouseEvent&) override;
-    virtual void on_mousemove(Layer&, MouseEvent&) override;
-    virtual void on_mouseup(Layer&, MouseEvent&) override;
-    virtual void on_second_paint(Layer const&, GUI::PaintEvent&) override;
+    virtual void on_mousedown(Layer*, MouseEvent&) override;
+    virtual void on_mousemove(Layer*, MouseEvent&) override;
+    virtual void on_mouseup(Layer*, MouseEvent&) override;
+    virtual void on_second_paint(Layer const*, GUI::PaintEvent&) override;
     virtual void on_keydown(GUI::KeyEvent&) override;
     virtual GUI::Widget* get_properties_widget() override;
     virtual Gfx::StandardCursor cursor() override { return Gfx::StandardCursor::Crosshair; }

Userland/Applications/PixelPaint/SprayTool.cpp

@@ -63,8 +63,11 @@ void SprayTool::paint_it()
     layer->did_modify_bitmap(Gfx::IntRect::centered_on(m_last_pos, Gfx::IntSize(base_radius * 2, base_radius * 2)));
 }
 
-void SprayTool::on_mousedown(Layer&, MouseEvent& event)
+void SprayTool::on_mousedown(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     auto& layer_event = event.layer_event();
     m_color = m_editor->color_for(layer_event);
     m_last_pos = layer_event.position();
@@ -72,8 +75,11 @@ void SprayTool::on_mousedown(Layer&, MouseEvent& event)
     paint_it();
 }
 
-void SprayTool::on_mousemove(Layer&, MouseEvent& event)
+void SprayTool::on_mousemove(Layer* layer, MouseEvent& event)
 {
+    if (!layer)
+        return;
+
     m_last_pos = event.layer_event().position();
     if (m_timer->is_active()) {
         paint_it();
@@ -81,7 +87,7 @@ void SprayTool::on_mousemove(Layer&, MouseEvent& event)
     }
 }
 
-void SprayTool::on_mouseup(Layer&, MouseEvent&)
+void SprayTool::on_mouseup(Layer*, MouseEvent&)
 {
     if (m_timer->is_active()) {
         m_timer->stop();

Userland/Applications/PixelPaint/SprayTool.h

@@ -18,9 +18,9 @@ public:
     SprayTool();
     virtual ~SprayTool() override;
 
-    virtual void on_mousedown(Layer&, MouseEvent&) override;
-    virtual void on_mouseup(Layer&, MouseEvent&) override;
-    virtual void on_mousemove(Layer&, MouseEvent&) override;
+    virtual void on_mousedown(Layer*, MouseEvent&) override;
+    virtual void on_mouseup(Layer*, MouseEvent&) override;
+    virtual void on_mousemove(Layer*, MouseEvent&) override;
     virtual GUI::Widget* get_properties_widget() override;
     virtual Gfx::StandardCursor cursor() override { return Gfx::StandardCursor::Crosshair; }
 

Userland/Applications/PixelPaint/Tool.h

@@ -48,12 +48,12 @@ public:
         GUI::MouseEvent& m_raw_event;
     };
 
-    virtual void on_mousedown(Layer&, MouseEvent&) { }
-    virtual void on_mousemove(Layer&, MouseEvent&) { }
-    virtual void on_mouseup(Layer&, MouseEvent&) { }
-    virtual void on_context_menu(Layer&, GUI::ContextMenuEvent&) { }
+    virtual void on_mousedown(Layer*, MouseEvent&) { }
+    virtual void on_mousemove(Layer*, MouseEvent&) { }
+    virtual void on_mouseup(Layer*, MouseEvent&) { }
+    virtual void on_context_menu(Layer*, GUI::ContextMenuEvent&) { }
     virtual void on_tool_button_contextmenu(GUI::ContextMenuEvent&) { }
-    virtual void on_second_paint(Layer const&, GUI::PaintEvent&) { }
+    virtual void on_second_paint(Layer const*, GUI::PaintEvent&) { }
     virtual void on_keydown(GUI::KeyEvent&) { }
     virtual void on_keyup(GUI::KeyEvent&) { }
     virtual void on_tool_activation() { }

Userland/Applications/PixelPaint/ZoomTool.cpp

@@ -20,7 +20,7 @@ ZoomTool::~ZoomTool()
 {
 }
 
-void ZoomTool::on_mousedown(Layer&, MouseEvent& event)
+void ZoomTool::on_mousedown(Layer*, MouseEvent& event)
 {
     auto& raw_event = event.raw_event();
     if (raw_event.button() != GUI::MouseButton::Left && raw_event.button() != GUI::MouseButton::Right)

Userland/Applications/PixelPaint/ZoomTool.h

@@ -17,7 +17,7 @@ public:
     ZoomTool();
     virtual ~ZoomTool() override;
 
-    virtual void on_mousedown(Layer&, MouseEvent&) override;
+    virtual void on_mousedown(Layer*, MouseEvent&) override;
     virtual GUI::Widget* get_properties_widget() override;
 
 private: