Introduce Cursor type in canvas

wgpu/src/widget/canvas/cursor.rs

@@ -0,0 +1,50 @@
+use iced_native::{Point, Rectangle};
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum Cursor {
+    Available(Point),
+    Unavailable,
+}
+
+impl Cursor {
+    // TODO: Remove this once this type is used in `iced_native` to encode
+    // proper cursor availability
+    pub(crate) fn from_window_position(position: Point) -> Self {
+        if position.x < 0.0 || position.y < 0.0 {
+            Cursor::Unavailable
+        } else {
+            Cursor::Available(position)
+        }
+    }
+
+    pub fn position(&self) -> Option<Point> {
+        match self {
+            Cursor::Available(position) => Some(*position),
+            Cursor::Unavailable => None,
+        }
+    }
+
+    pub fn relative_position(&self, bounds: &Rectangle) -> Option<Point> {
+        match self {
+            Cursor::Available(position) => {
+                Some(Point::new(position.x - bounds.x, position.y - bounds.y))
+            }
+            _ => None,
+        }
+    }
+
+    pub fn internal_position(&self, bounds: &Rectangle) -> Option<Point> {
+        if self.is_over(bounds) {
+            self.relative_position(bounds)
+        } else {
+            None
+        }
+    }
+
+    pub fn is_over(&self, bounds: &Rectangle) -> bool {
+        match self {
+            Cursor::Available(position) => bounds.contains(*position),
+            Cursor::Unavailable => false,
+        }
+    }
+}

wgpu/src/widget/canvas/program.rs

@@ -1,14 +1,19 @@
-use crate::canvas::{Event, Geometry, Size};
-use iced_native::MouseCursor;
+use crate::canvas::{Cursor, Event, Geometry};
+use iced_native::{MouseCursor, Rectangle};
 
 pub trait Program<Message> {
-    fn update(&mut self, _event: Event, _bounds: Size) -> Option<Message> {
+    fn update(
+        &mut self,
+        _event: Event,
+        _bounds: Rectangle,
+        _cursor: Cursor,
+    ) -> Option<Message> {
         None
     }
 
-    fn draw(&self, bounds: Size) -> Vec<Geometry>;
+    fn draw(&self, bounds: Rectangle, cursor: Cursor) -> Vec<Geometry>;
 
-    fn mouse_cursor(&self, _bounds: Size) -> MouseCursor {
+    fn mouse_cursor(&self, _bounds: Rectangle, _cursor: Cursor) -> MouseCursor {
         MouseCursor::default()
     }
 }
@@ -17,15 +22,20 @@ impl<T, Message> Program<Message> for &mut T
 where
     T: Program<Message>,
 {
-    fn update(&mut self, event: Event, bounds: Size) -> Option<Message> {
-        T::update(self, event, bounds)
+    fn update(
+        &mut self,
+        event: Event,
+        bounds: Rectangle,
+        cursor: Cursor,
+    ) -> Option<Message> {
+        T::update(self, event, bounds, cursor)
     }
 
-    fn draw(&self, bounds: Size) -> Vec<Geometry> {
-        T::draw(self, bounds)
+    fn draw(&self, bounds: Rectangle, cursor: Cursor) -> Vec<Geometry> {
+        T::draw(self, bounds, cursor)
     }
 
-    fn mouse_cursor(&self, bounds: Size) -> MouseCursor {
-        T::mouse_cursor(self, bounds)
+    fn mouse_cursor(&self, bounds: Rectangle, cursor: Cursor) -> MouseCursor {
+        T::mouse_cursor(self, bounds, cursor)
     }
 }