module dia.icanvas;

import tk.geometry;
import tk.events;
import cairo.Context;

interface Viewport {
    void zoom_relative(Point pixel_datum, double factor);
    void pan_relative(Vector pixel_displacement);
    void damage_model(Rectangle area);      // FIXME could be an inout parameter of the event handling, or a special scope Damage object that supports growth only
    void damage_pixel(Rectangle area);      // FIXME as above

    // FIXME not sure about these:
    double zoom() const;
    Point model_to_pixel(Point model) const;
    Point pixel_to_model(Point pixel) const;
    Vector model_to_pixel(Vector model) const;
    Vector pixel_to_model(Vector pixel) const;
    Rectangle model_to_pixel(Rectangle model) const;
    Rectangle pixel_to_model(Rectangle model) const;
    double model_to_pixel(double model) const;
    double pixel_to_model(double pixel) const;
}

interface EventHandler {
    bool handle_button_press(Viewport viewport, in ButtonEvent event);
    bool handle_button_release(Viewport viewport, in ButtonEvent event);
    bool handle_motion(Viewport viewport, in MotionEvent event);
    bool handle_scroll(Viewport viewport, in ScrollEvent event);
    //bool handle_enter(Viewport viewport, CrossingEvent event);
    //bool handle_leave(Viewport viewport, CrossingEvent event);
    //bool handle_focus_in(Viewport viewport, FocusEvent event);
    //bool handle_focus_out(Viewport viewport, FocusEvent event);
    bool handle_key_press(Viewport viewport, in KeyEvent event);
    bool handle_key_release(Viewport viewport, in KeyEvent event);
}

abstract class Layer {
    this(in string name) {
        mName = name;
    }

    string name() const { return mName; }

    Rectangle bounds() const;
    //void zoom_changed
    void draw(const Viewport viewport,
              in Rectangle pixel_damage, scope Context pixel_cr,
              in Rectangle model_damage, scope Context model_cr) const;

    private {
        invariant string mName;
    }
}