[WIP] CanvasElement trait (currently panicking

src/main.rs

@@ -14,37 +14,107 @@
 
 //! An example of a custom drawing widget.
 
+use std::rc::Rc;
 use druid::im::{vector, Vector};
 use druid::kurbo::BezPath;
-use druid::piet::{FontFamily, ImageFormat, InterpolationMode};
 use druid::widget::prelude::*;
 use druid::{
-    Affine, AppLauncher, ArcStr, Color, Data, Event, FontDescriptor, LocalizedString, Point, Rect, TextLayout,
-    WindowDesc,
+    AppLauncher, Color, Data, Event, LocalizedString, Rect, WindowDesc,
 };
 
-#[derive(Clone, Data)]
-struct CanvasData {
-    drawn_paths: Vector<BezPath>,
-    is_drawing: bool,
+mod stiletto {
+    use druid::widget::prelude::*;
+    pub trait CanvasElement { //: CanvasElementData {
+        /// returns the axis-aligned bounding box
+        fn bounding_box(&self) -> druid::Rect;
+
+        fn draw(&self, ctx: &mut druid::PaintCtx);
+
+        fn get_path(&mut self) -> Option<&mut CanvasPath> {
+            None
+        }
+    }
+
+    //pub trait CanvasElementData {
+    //    fn clone_box(&self) -> Box<dyn CanvasElement>;
+    //    fn same_box(&self, other: &Box<dyn CanvasElement>) -> bool;
+    //}
+
+    //impl<T> CanvasElementData for T
+    //where
+    //    T: 'static + CanvasElement + druid::Data
+    //{
+    //   fn clone_box(&self) -> Box<dyn CanvasElement> {
+    //       Box::new(self.clone())
+    //   }
+
+    //   fn same_box(&self, other: &Box<T>) -> bool {
+    //       self.same(other)
+    //   }
+    //}
+
+    //impl druid::Data for Box<dyn CanvasElement> {
+    //    fn same(&self, other: &Self) -> bool {
+    //        return self.same(other);
+    //    }
+    //}
+
+    //impl Clone for Box<dyn CanvasElement> {
+    //    fn clone(&self) -> Self {
+    //        self.clone_box()
+    //    }
+    //}
+
+    #[derive(Clone, druid::Data)]
+    pub struct CanvasPath {
+        pub kurbo_path: druid::kurbo::BezPath,
+    }
+
+    impl CanvasElement for CanvasPath {
+        fn bounding_box(&self) -> druid::Rect {
+            use druid::kurbo::Shape;
+            return self.kurbo_path.bounding_box();
+        }
+
+        fn get_path(&mut self) -> Option<&mut CanvasPath> {
+            Some(self)
+        }
+
+        fn draw(&self, ctx: &mut druid::PaintCtx) {
+            let stroke_color = druid::Color::rgb8(0, 128, 0);
+            ctx.stroke(&self.kurbo_path, &stroke_color, 2.0);
+        }
+    }
+
+
 }
 
 struct CanvasWidget;
 
+#[derive(Clone, Data)]
+struct CanvasData {
+    elements: Vector<Rc<dyn stiletto::CanvasElement>>,
+    is_drawing: bool,
+}
+
 impl Widget<CanvasData> for CanvasWidget {
-    fn event(&mut self, _ctx: &mut EventCtx, event: &Event, data: &mut CanvasData, _env: &Env) {
+    fn event<'a>(&mut self, _ctx: &mut EventCtx, event: &Event, data: &'a mut CanvasData, _env: &Env) {
         match event {
            Event::MouseDown(mouse_event) => {
                if mouse_event.pointer_type == druid::PointerType::Stylus {
                    data.is_drawing = true;
-                   let mut new_path = BezPath::new();
-                   new_path.move_to((mouse_event.pos.x, mouse_event.pos.y));
-                   data.drawn_paths.push_back(new_path);
+                   let mut kurbo_path = BezPath::new();
+                   kurbo_path.move_to((mouse_event.pos.x, mouse_event.pos.y));
+                   let new_path = Rc::new(stiletto::CanvasPath{kurbo_path});
+                   data.elements.push_back(new_path);
                }
            },
            Event::MouseMove(mouse_event) => {
                if data.is_drawing && mouse_event.pointer_type == druid::PointerType::Stylus {
-                   data.drawn_paths.back_mut().unwrap().line_to((mouse_event.pos.x, mouse_event.pos.y));
+                   let ptr: &'a mut dyn stiletto::CanvasElement = Rc::get_mut(data.elements.back_mut().unwrap()).unwrap();
+                   let last_canvas_path: &'a mut stiletto::CanvasPath = ptr.get_path().unwrap();
+
+                   last_canvas_path.kurbo_path.line_to((mouse_event.pos.x, mouse_event.pos.y));
                }
            },
            Event::MouseUp(_) => {
@@ -67,7 +137,7 @@ impl Widget<CanvasData> for CanvasWidget {
     }
 
     fn update(&mut self, ctx: &mut UpdateCtx, _old_data: &CanvasData, _data: &CanvasData, _env: &Env) {
-        ctx.request_paint();
+        ctx.request_paint_rect(Rect::new(0., 0., 200., 200.));
     }
 
     fn layout(
@@ -97,23 +167,20 @@ impl Widget<CanvasData> for CanvasWidget {
         let size = ctx.size();
         let rect = size.to_rect();
         ctx.fill(rect, &Color::WHITE);
-
         // Note: ctx also has a `clear` method, but that clears the whole context,
         // and we only want to clear this widget's area.
-
-        let stroke_color = Color::rgb8(0, 128, 0);
-        for path in &data.drawn_paths {
-            ctx.stroke(path, &stroke_color, 2.0);
+        for element in &data.elements {
+            element.draw(ctx);
         }
     }
 }
 
 pub fn main() {
-    let window = WindowDesc::new(|| CanvasWidget {}).title(
-        LocalizedString::new("custom-widget-demo-window-title").with_placeholder("Fancy Colors"),
-    );
+    let window = WindowDesc::new(|| CanvasWidget {})
+        //.window_size((1024.0, 1400.0))
+        .title(LocalizedString::new("custom-widget-demo-window-title").with_placeholder("Fancy Colors"));
     let canvas_data = CanvasData {
-        drawn_paths: vector![],
+        elements: vector![],
         is_drawing: false,
     };
     AppLauncher::with_window(window)