PixelPaint: Add GuideTool for editing Guides

This patch adds the logic for the GuideTool. Pulling in from outside the
image creates a new Guide, moving a Guide outside of the image deletes
it and a Guide can be deleteted via the context menu.
A Guide is considered clicked when the cursor is less than 20 pixels
away from the line.

Userland/Applications/PixelPaint/CMakeLists.txt

@@ -17,6 +17,7 @@ set(SOURCES
     CreateNewLayerDialog.cpp
     EllipseTool.cpp
     EraseTool.cpp
+    GuideTool.cpp
     Image.cpp
     ImageEditor.cpp
     Layer.cpp

Userland/Applications/PixelPaint/GuideTool.cpp

@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2021, Tobias Christiansen <tobi@tobyase.de>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "GuideTool.h"
+#include "ImageEditor.h"
+#include <LibGUI/Menu.h>
+
+namespace PixelPaint {
+
+GuideTool::GuideTool()
+{
+}
+
+GuideTool::~GuideTool()
+{
+}
+
+RefPtr<Guide> GuideTool::closest_guide(const Gfx::IntPoint& point)
+{
+    auto guides = editor()->guides();
+    Guide* closest_guide = nullptr;
+    int closest_guide_distance = NumericLimits<int>::max();
+
+    for (auto& guide : guides) {
+        int relevant_position = 0;
+        if (guide.orientation() == Guide::Orientation::Horizontal)
+            relevant_position = point.y();
+        else if (guide.orientation() == Guide::Orientation::Vertical)
+            relevant_position = point.x();
+
+        auto distance = abs(relevant_position - (int)guide.offset());
+
+        if (distance < closest_guide_distance) {
+            closest_guide = &guide;
+            closest_guide_distance = distance;
+        }
+    }
+
+    if (closest_guide_distance < 20)
+        return closest_guide;
+    return nullptr;
+}
+
+void GuideTool::on_mousedown(Layer&, GUI::MouseEvent& mouse_event, GUI::MouseEvent& image_event)
+{
+    if (!m_editor)
+        return;
+
+    if (mouse_event.button() != GUI::MouseButton::Left)
+        return;
+
+    RefPtr<Guide> new_guide;
+    if (image_event.position().x() < 0 || image_event.position().x() > editor()->image().size().width()) {
+        new_guide = Guide::construct(Guide::Orientation::Vertical, image_event.position().x());
+    } else if (image_event.position().y() < 0 || image_event.position().y() > editor()->image().size().height()) {
+        new_guide = Guide::construct(Guide::Orientation::Horizontal, image_event.position().y());
+    }
+
+    if (new_guide) {
+        m_selected_guide = new_guide;
+        m_guide_origin = 0;
+        editor()->add_guide(new_guide.release_nonnull());
+        return;
+    }
+
+    m_event_origin = image_event.position();
+
+    m_selected_guide = closest_guide(image_event.position());
+
+    if (m_selected_guide)
+        m_guide_origin = m_selected_guide->offset();
+}
+
+void GuideTool::on_mouseup(Layer&, GUI::MouseEvent&, GUI::MouseEvent&)
+{
+    m_guide_origin = 0;
+    m_event_origin = { 0, 0 };
+
+    if (!m_selected_guide)
+        return;
+
+    if (m_selected_guide->offset() < 0
+        || (m_selected_guide->orientation() == Guide::Orientation::Horizontal && m_selected_guide->offset() > editor()->image().size().height())
+        || (m_selected_guide->orientation() == Guide::Orientation::Vertical && m_selected_guide->offset() > editor()->image().size().width())) {
+        editor()->remove_guide(*m_selected_guide);
+        editor()->layers_did_change();
+    }
+
+    m_selected_guide = nullptr;
+}
+
+void GuideTool::on_mousemove(Layer&, GUI::MouseEvent&, GUI::MouseEvent& image_event)
+{
+    if (!m_selected_guide)
+        return;
+
+    auto delta = image_event.position() - m_event_origin;
+
+    auto relevant_offset = 0;
+    if (m_selected_guide->orientation() == Guide::Orientation::Horizontal)
+        relevant_offset = delta.y();
+    else if (m_selected_guide->orientation() == Guide::Orientation::Vertical)
+        relevant_offset = delta.x();
+
+    auto new_offset = (float)relevant_offset + m_guide_origin;
+    m_selected_guide->set_offset(new_offset);
+
+    editor()->layers_did_change();
+}
+
+void GuideTool::on_context_menu(Layer&, GUI::ContextMenuEvent& event)
+{
+    if (!m_context_menu) {
+        m_context_menu = GUI::Menu::construct();
+        m_context_menu->add_action(GUI::Action::create(
+            "&Delete Guide", Gfx::Bitmap::try_load_from_file("/res/icons/16x16/delete.png"), [this](auto&) {
+                if (!m_context_menu_guide)
+                    return;
+                editor()->remove_guide(*m_context_menu_guide);
+                m_selected_guide = nullptr;
+                m_guide_origin = 0;
+                editor()->layers_did_change();
+            },
+            editor()));
+    }
+
+    auto image_position = editor()->editor_position_to_image_position(event.position());
+    m_context_menu_guide = closest_guide({ (int)image_position.x(), (int)image_position.y() });
+    m_context_menu->popup(event.screen_position());
+}
+
+}

Userland/Applications/PixelPaint/GuideTool.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2021, Tobias Christiansen <tobi@tobyase.de>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include "Guide.h"
+#include "Tool.h"
+#include <AK/RefPtr.h>
+
+namespace PixelPaint {
+
+class GuideTool final : public Tool {
+public:
+    GuideTool();
+
+    virtual ~GuideTool() override;
+
+    virtual void on_mousedown(Layer&, GUI::MouseEvent& layer_event, GUI::MouseEvent& image_event) override;
+    virtual void on_mousemove(Layer&, GUI::MouseEvent& layer_event, GUI::MouseEvent& image_event) override;
+    virtual void on_mouseup(Layer&, GUI::MouseEvent& layer_event, GUI::MouseEvent& image_event) override;
+    virtual void on_context_menu(Layer&, GUI::ContextMenuEvent&) override;
+
+private:
+    RefPtr<Guide> closest_guide(Gfx::IntPoint const&);
+
+    RefPtr<Guide> m_selected_guide;
+    RefPtr<Guide> m_context_menu_guide;
+    Gfx::IntPoint m_event_origin;
+    float m_guide_origin { 0 };
+    RefPtr<GUI::Menu> m_context_menu;
+};
+}