1 files changed, 117 insertions, 0 deletions
diff --git a/src/ui/widget/gradient-with-stops.h b/src/ui/widget/gradient-with-stops.h
new file mode 100644
index 0000000..0276fa2
--- /dev/null
+++ b/src/ui/widget/gradient-with-stops.h
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#ifndef SEEN_GRADIENT_WITH_STOPS_H
+#define SEEN_GRADIENT_WITH_STOPS_H
+
+#include <gtkmm/widget.h>
+#include <gdkmm/color.h>
+#include "ui/svg-renderer.h"
+#include "helper/auto-connection.h"
+
+class SPGradient;
+
+namespace Inkscape {
+namespace UI {
+namespace Widget {
+
+class GradientWithStops : public Gtk::DrawingArea {
+public:
+    GradientWithStops();
+
+    // gradient to draw or nullptr
+    void set_gradient(SPGradient* gradient);
+
+    // set selected stop handle (or pass -1 to deselect)
+    void set_focused_stop(int index);
+
+    // stop has been selected
+    sigc::signal<void (size_t)>& signal_stop_selected() {
+        return _signal_stop_selected;
+    }
+
+    // request to change stop's offset
+    sigc::signal<void (size_t, double)>& signal_stop_offset_changed() {
+        return _signal_stop_offset_changed;
+    }
+
+    sigc::signal<void (double)>& signal_add_stop_at() {
+        return _signal_add_stop_at;
+    }
+
+    sigc::signal<void (size_t)>& signal_delete_stop() {
+        return _signal_delete_stop;
+    }
+
+private:
+    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;
+    bool on_draw(const Cairo::RefPtr<Cairo::Context>& cr) override;
+    void on_style_updated() override;
+    bool on_button_press_event(GdkEventButton* event) override;
+    bool on_button_release_event(GdkEventButton* event) override;
+    bool on_motion_notify_event(GdkEventMotion* event) override;
+    bool on_key_press_event(GdkEventKey* key_event) override;
+    bool on_focus_in_event(GdkEventFocus* event) override;
+    bool on_focus_out_event(GdkEventFocus* event) override;
+    bool on_focus(Gtk::DirectionType direction) override;
+    void size_request(GtkRequisition* requisition) const;
+    void modified();
+    // repaint widget
+    void update();
+    // index of gradient stop handle under (x, y) or -1
+    int find_stop_at(double x, double y) const;
+    // request stop move
+    void move_stop(int stop_index, double offset_shift);
+
+    // layout of gradient image/editor
+    struct layout_t {
+        double x, y, width, height;
+    };
+    layout_t get_layout() const;
+
+    // position of single gradient stop handle
+    struct stop_pos_t {
+        double left, tip, right, top, bottom;
+    };
+    stop_pos_t get_stop_position(size_t index, const layout_t& layout) const;
+
+    struct limits_t {
+        double min_offset, max_offset, offset;
+    };
+    limits_t get_stop_limits(int index) const;
+    GdkCursor* get_cursor(double x, double y) const;
+
+    SPGradient* _gradient = nullptr;
+    struct stop_t {
+        double offset;
+        SPColor color;
+        double opacity;
+    };
+    std::vector<stop_t> _stops;
+    // handle stop SVG template
+    svg_renderer _template;
+    // selected handle indicator
+    svg_renderer _tip_template;
+    auto_connection _release;
+    auto_connection _modified;
+    Gdk::RGBA _background_color;
+    sigc::signal<void (size_t)> _signal_stop_selected;
+    sigc::signal<void (size_t, double)> _signal_stop_offset_changed;
+    sigc::signal<void (double)> _signal_add_stop_at;
+    sigc::signal<void (size_t)> _signal_delete_stop;
+    bool _dragging = false;
+    // index of handle stop that user clicked; may be out of range
+    int _focused_stop = -1;
+    double _pointer_x = 0;
+    double _stop_offset = 0;
+    Glib::RefPtr<Gdk::Cursor> _cursor_mouseover;
+    Glib::RefPtr<Gdk::Cursor> _cursor_dragging;
+    Glib::RefPtr<Gdk::Cursor> _cursor_insert;
+    // TODO: customize this amount or read prefs
+    double _stop_move_increment = 0.01;
+};
+
+} // namespace Widget
+} // namespace UI
+} // namespace Inkscape
+
+#endif