1 files changed, 234 insertions, 0 deletions
diff --git a/src/ui/widget/canvas.h b/src/ui/widget/canvas.h
new file mode 100644
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+++ b/src/ui/widget/canvas.h
@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#ifndef INKSCAPE_UI_WIDGET_CANVAS_H
+#define INKSCAPE_UI_WIDGET_CANVAS_H
+/*
+ * Authors:
+ *   Tavmjong Bah
+ *   PBS <pbs3141@gmail.com>
+ *
+ * Copyright (C) 2022 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <memory>
+#include <gtkmm.h>
+#include <2geom/rect.h>
+#include <2geom/int-rect.h>
+#include "display/rendermode.h"
+
+class SPDesktop;
+
+namespace Inkscape {
+
+class CanvasItem;
+class CanvasItemGroup;
+class Drawing;
+
+namespace UI {
+namespace Widget {
+
+class CanvasPrivate;
+
+/**
+ * A Gtk::DrawingArea widget for Inkscape's canvas.
+ */ 
+class Canvas : public Gtk::DrawingArea
+{
+    using parent_type = Gtk::DrawingArea;
+
+public:
+
+    Canvas();
+    ~Canvas() override;
+
+    /* Configuration */
+
+    // Desktop (Todo: Remove.)
+    void set_desktop(SPDesktop *desktop) { _desktop = desktop; }
+    SPDesktop *get_desktop() const { return _desktop; }
+
+    // Drawing
+    void set_drawing(Inkscape::Drawing *drawing);
+
+    // Canvas item root
+    CanvasItemGroup *get_canvas_item_root() const { return _canvas_item_root; }
+
+    // Geometry
+    void set_pos   (const Geom::IntPoint &pos);
+    void set_pos   (const Geom::Point    &fpos) { set_pos(fpos.round()); }
+    void set_affine(const Geom::Affine   &affine);
+    const Geom::IntPoint& get_pos   () const {return _pos;}
+    const Geom::Affine&   get_affine() const {return _affine;}
+
+    // Background
+    void set_background_color(guint32 rgba);
+    void set_background_checkerboard(guint32 rgba = 0xC4C4C4FF, bool use_alpha = false);
+
+    //  Rendering modes
+    void set_render_mode(Inkscape::RenderMode mode);
+    void set_color_mode (Inkscape::ColorMode  mode);
+    void set_split_mode (Inkscape::SplitMode  mode);
+    Inkscape::RenderMode get_render_mode() const { return _render_mode; }
+    Inkscape::ColorMode  get_color_mode()  const { return _color_mode; }
+    Inkscape::SplitMode  get_split_mode()  const { return _split_mode; }
+
+    // CMS
+    void set_cms_key(std::string key) {
+        _cms_key = std::move(key);
+        _cms_active = !_cms_key.empty();
+    }
+    const std::string& get_cms_key() const { return _cms_key; }
+    void set_cms_active(bool active) { _cms_active = active; }
+    bool get_cms_active() const { return _cms_active; }
+
+    /* Observers */
+
+    // Geometry
+    Geom::IntPoint get_dimensions() const;
+    bool world_point_inside_canvas(Geom::Point const &world) const; // desktop-events.cpp
+    Geom::Point canvas_to_world(Geom::Point const &window) const;
+    Geom::IntRect get_area_world() const;
+
+    // State
+    bool is_dragging() const { return _is_dragging; } // selection-chemistry.cpp
+
+    // Encapsulation leaks
+    Cairo::RefPtr<Cairo::ImageSurface> get_backing_store() const; // canvas-item-rotate.cpp
+    Cairo::RefPtr<Cairo::Pattern>      get_background_pattern() const { return _background; } // canvas-item-rect.cpp, canvas-item-ctrl.cpp
+
+    /* Methods */
+
+    // Invalidation
+    void redraw_all();                                // Mark everything as having changed.
+    void redraw_area(Geom::Rect& area);               // Mark a rectangle of world space as having changed.
+    void redraw_area(int x0, int y0, int x1, int y1);
+    void redraw_area(Geom::Coord x0, Geom::Coord y0, Geom::Coord x1, Geom::Coord y1);
+    void request_update();                            // Mark geometry as needing recalculation.
+
+    // Gobblers (tool-base.cpp)
+    int gobble_key_events(guint keyval, guint mask);
+    void gobble_motion_events(guint mask);
+
+    // Callback run on destructor of any canvas item
+    void canvas_item_destructed(Inkscape::CanvasItem *item);
+
+    // State
+    Inkscape::CanvasItem *get_current_canvas_item() const { return _current_canvas_item; }
+    void                  set_current_canvas_item(Inkscape::CanvasItem *item) {
+        _current_canvas_item = item;
+    }
+    Inkscape::CanvasItem *get_grabbed_canvas_item() const { return _grabbed_canvas_item; }
+    void                  set_grabbed_canvas_item(Inkscape::CanvasItem *item, Gdk::EventMask mask) {
+        _grabbed_canvas_item = item;
+        _grabbed_event_mask = mask;
+    }
+    void set_drawing_disabled(bool disable); // Disable during path ops, etc.
+    void set_all_enter_events(bool on) { _all_enter_events = on; }
+
+protected:
+
+    void get_preferred_width_vfunc (int &minimum_width,  int &natural_width ) const override;
+    void get_preferred_height_vfunc(int &minimum_height, int &natural_height) const override;
+
+    // Event handlers
+    bool on_scroll_event        (GdkEventScroll*  ) override;
+    bool on_button_event        (GdkEventButton*  );
+    bool on_button_press_event  (GdkEventButton*  ) override;
+    bool on_button_release_event(GdkEventButton*  ) override;
+    bool on_enter_notify_event  (GdkEventCrossing*) override;
+    bool on_leave_notify_event  (GdkEventCrossing*) override;
+    bool on_focus_in_event      (GdkEventFocus*   ) override;
+    bool on_key_press_event     (GdkEventKey*     ) override;
+    bool on_key_release_event   (GdkEventKey*     ) override;
+    bool on_motion_notify_event (GdkEventMotion*  ) override;
+
+    void on_realize() override;
+    void on_unrealize() override;
+    void on_size_allocate(Gtk::Allocation&) override;
+    bool on_draw(const Cairo::RefPtr<Cairo::Context>&) override;
+
+private:
+
+    /* Configuration */
+
+    // Desktop
+    SPDesktop *_desktop = nullptr;
+
+    // Drawing
+    Inkscape::Drawing *_drawing = nullptr;
+
+    // Canvas item root
+    CanvasItemGroup *_canvas_item_root = nullptr;
+
+    // Geometry
+    Geom::IntPoint _pos;   ///< Coordinates of top-left pixel of canvas view within canvas.
+    Geom::Affine _affine;  ///< The affine that we have been requested to draw at.
+
+    // Background
+    Cairo::RefPtr<Cairo::Pattern> _background; ///< The background of the widget.
+
+    // Rendering modes
+    Inkscape::RenderMode _render_mode = Inkscape::RenderMode::NORMAL;
+    Inkscape::SplitMode _split_mode = Inkscape::SplitMode::NORMAL;
+    Inkscape::ColorMode _color_mode = Inkscape::ColorMode::NORMAL;
+
+    // CMS
+    std::string _cms_key;
+    bool _cms_active = false;
+
+    /* Internal state */
+
+    // Event handling/item picking
+    GdkEvent _pick_event;         ///< Event used to find currently selected item.
+    bool     _in_repick;          ///< For tracking recursion of pick_current_item().
+    bool     _left_grabbed_item;  ///< ?
+    bool     _all_enter_events;   ///< Keep all enter events. Only set true in connector-tool.cpp.
+    bool     _is_dragging;        ///< Used in selection-chemistry to block undo/redo.
+    int      _state;              ///< Last known modifier state (SHIFT, CTRL, etc.).
+
+    Inkscape::CanvasItem *_current_canvas_item;      ///< Item containing cursor, nullptr if none.
+    Inkscape::CanvasItem *_current_canvas_item_new;  ///< Item to become _current_item, nullptr if none.
+    Inkscape::CanvasItem *_grabbed_canvas_item;      ///< Item that holds a pointer grab; nullptr if none.
+    Gdk::EventMask _grabbed_event_mask;
+
+    // Drawing
+    bool _drawing_disabled = false;  ///< Disable drawing during critical operations
+    bool _need_update = true; // Set true so setting CanvasItem bounds are calculated at least once.
+
+    // Split view
+    Inkscape::SplitDirection _split_direction;
+    Geom::Point _split_position;
+    Inkscape::SplitDirection _hover_direction;
+    bool _split_dragging;
+    Geom::Point _split_drag_start;
+
+    void add_clippath(const Cairo::RefPtr<Cairo::Context>&);
+    void set_cursor();
+
+    // Opaque pointer to implementation
+    friend class CanvasPrivate;
+    std::unique_ptr<CanvasPrivate> d;
+};
+
+} // namespace Widget
+} // namespace UI
+} // namespace Inkscape
+
+#endif // INKSCAPE_UI_WIDGET_CANVAS_H
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :