Introduce `Cursor` type in `canvas`

6 files changed, 171 insertions, 110 deletions

diff --git a/examples/bezier_tool/src/main.rs b/examples/bezier_tool/src/main.rs
index 8c9ebd75..6473db75 100644
--- a/examples/bezier_tool/src/main.rs
+++ b/examples/bezier_tool/src/main.rs
@@ -69,15 +69,13 @@ impl Sandbox for Example {
 
 mod bezier {
     use iced::{
-        canvas::{self, Canvas, Event, Frame, Geometry, Path, Stroke},
+        canvas::{self, Canvas, Cursor, Event, Frame, Geometry, Path, Stroke},
         mouse, ButtonState, Element, Length, MouseCursor, Point, Rectangle,
-        Size,
     };
 
     #[derive(Default)]
     pub struct State {
         pending: Option<Pending>,
-        cursor_position: Point,
         cache: canvas::Cache,
     }
 
@@ -106,64 +104,62 @@ mod bezier {
     }
 
     impl<'a> canvas::Program<Curve> for Bezier<'a> {
-        fn update(&mut self, event: Event, bounds: Size) -> Option<Curve> {
+        fn update(
+            &mut self,
+            event: Event,
+            bounds: Rectangle,
+            cursor: Cursor,
+        ) -> Option<Curve> {
+            let cursor_position = cursor.internal_position(&bounds)?;
+
             match event {
                 Event::Mouse(mouse_event) => match mouse_event {
-                    mouse::Event::CursorMoved { x, y } => {
-                        self.state.cursor_position = Point::new(x, y);
-
-                        None
-                    }
                     mouse::Event::Input {
                         button: mouse::Button::Left,
                         state: ButtonState::Pressed,
-                    } if Rectangle::with_size(bounds)
-                        .contains(self.state.cursor_position) =>
-                    {
-                        match self.state.pending {
-                            None => {
-                                self.state.pending = Some(Pending::One {
-                                    from: self.state.cursor_position,
-                                });
-                                None
-                            }
-                            Some(Pending::One { from }) => {
-                                self.state.pending = Some(Pending::Two {
-                                    from,
-                                    to: self.state.cursor_position,
-                                });
-
-                                None
-                            }
-                            Some(Pending::Two { from, to }) => {
-                                self.state.pending = None;
-
-                                Some(Curve {
-                                    from,
-                                    to,
-                                    control: self.state.cursor_position,
-                                })
-                            }
+                    } => match self.state.pending {
+                        None => {
+                            self.state.pending = Some(Pending::One {
+                                from: cursor_position,
+                            });
+                            None
                         }
-                    }
+                        Some(Pending::One { from }) => {
+                            self.state.pending = Some(Pending::Two {
+                                from,
+                                to: cursor_position,
+                            });
+
+                            None
+                        }
+                        Some(Pending::Two { from, to }) => {
+                            self.state.pending = None;
+
+                            Some(Curve {
+                                from,
+                                to,
+                                control: cursor_position,
+                            })
+                        }
+                    },
                     _ => None,
                 },
             }
         }
 
-        fn draw(&self, bounds: Size) -> Vec<Geometry> {
-            let content = self.state.cache.draw(bounds, |frame: &mut Frame| {
-                Curve::draw_all(self.curves, frame);
+        fn draw(&self, bounds: Rectangle, cursor: Cursor) -> Vec<Geometry> {
+            let content =
+                self.state.cache.draw(bounds.size(), |frame: &mut Frame| {
+                    Curve::draw_all(self.curves, frame);
 
-                frame.stroke(
-                    &Path::rectangle(Point::ORIGIN, frame.size()),
-                    Stroke::default(),
-                );
-            });
+                    frame.stroke(
+                        &Path::rectangle(Point::ORIGIN, frame.size()),
+                        Stroke::default(),
+                    );
+                });
 
             if let Some(pending) = &self.state.pending {
-                let pending_curve =
-                    pending.draw(bounds, self.state.cursor_position);
+                let pending_curve = pending.draw(bounds, cursor);
 
                 vec![content, pending_curve]
             } else {
@@ -171,9 +167,12 @@ mod bezier {
             }
         }
 
-        fn mouse_cursor(&self, bounds: Size) -> MouseCursor {
-            if Rectangle::with_size(bounds).contains(self.state.cursor_position)
-            {
+        fn mouse_cursor(
+            &self,
+            bounds: Rectangle,
+            cursor: Cursor,
+        ) -> MouseCursor {
+            if cursor.is_over(&bounds) {
                 MouseCursor::Crosshair
             } else {
                 MouseCursor::default()
@@ -208,24 +207,26 @@ mod bezier {
     }
 
     impl Pending {
-        fn draw(&self, bounds: Size, cursor_position: Point) -> Geometry {
-            let mut frame = Frame::new(bounds);
-
-            match *self {
-                Pending::One { from } => {
-                    let line = Path::line(from, cursor_position);
-                    frame.stroke(&line, Stroke::default().with_width(2.0));
-                }
-                Pending::Two { from, to } => {
-                    let curve = Curve {
-                        from,
-                        to,
-                        control: cursor_position,
-                    };
-
-                    Curve::draw_all(&[curve], &mut frame);
-                }
-            };
+        fn draw(&self, bounds: Rectangle, cursor: Cursor) -> Geometry {
+            let mut frame = Frame::new(bounds.size());
+
+            if let Some(cursor_position) = cursor.internal_position(&bounds) {
+                match *self {
+                    Pending::One { from } => {
+                        let line = Path::line(from, cursor_position);
+                        frame.stroke(&line, Stroke::default().with_width(2.0));
+                    }
+                    Pending::Two { from, to } => {
+                        let curve = Curve {
+                            from,
+                            to,
+                            control: cursor_position,
+                        };
+
+                        Curve::draw_all(&[curve], &mut frame);
+                    }
+                };
+            }
 
             frame.into_geometry()
         }
diff --git a/examples/clock/src/main.rs b/examples/clock/src/main.rs
index c2beddef..e6b17d8a 100644
--- a/examples/clock/src/main.rs
+++ b/examples/clock/src/main.rs
@@ -1,7 +1,7 @@
 use iced::{
-    canvas::{self, Cache, Canvas, Geometry, LineCap, Path, Stroke},
+    canvas::{self, Cache, Canvas, Cursor, Geometry, LineCap, Path, Stroke},
     executor, Application, Color, Command, Container, Element, Length, Point,
-    Settings, Size, Subscription, Vector,
+    Rectangle, Settings, Subscription, Vector,
 };
 
 pub fn main() {
@@ -75,10 +75,10 @@ impl Application for Clock {
 }
 
 impl canvas::Program<Message> for Clock {
-    fn draw(&self, bounds: Size) -> Vec<Geometry> {
+    fn draw(&self, bounds: Rectangle, _cursor: Cursor) -> Vec<Geometry> {
         use chrono::Timelike;
 
-        let clock = self.clock.draw(bounds, |frame| {
+        let clock = self.clock.draw(bounds.size(), |frame| {
             let center = frame.center();
             let radius = frame.width().min(frame.height()) / 2.0;
 
diff --git a/examples/solar_system/src/main.rs b/examples/solar_system/src/main.rs
index e2f107bd..a25e43df 100644
--- a/examples/solar_system/src/main.rs
+++ b/examples/solar_system/src/main.rs
@@ -7,8 +7,9 @@
 //!
 //! [1]: https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Basic_animations#An_animated_solar_system
 use iced::{
-    canvas, executor, window, Application, Canvas, Color, Command, Element,
-    Length, Point, Settings, Size, Subscription, Vector,
+    canvas::{self, Cursor, Path, Stroke},
+    executor, window, Application, Canvas, Color, Command, Element, Length,
+    Point, Rectangle, Settings, Size, Subscription, Vector,
 };
 
 use std::time::Instant;
@@ -132,11 +133,14 @@ impl State {
 }
 
 impl<Message> canvas::Program<Message> for State {
-    fn draw(&self, bounds: Size) -> Vec<canvas::Geometry> {
-        use canvas::{Path, Stroke};
+    fn draw(
+        &self,
+        bounds: Rectangle,
+        _cursor: Cursor,
+    ) -> Vec<canvas::Geometry> {
         use std::f32::consts::PI;
 
-        let background = self.space_cache.draw(bounds, |frame| {
+        let background = self.space_cache.draw(bounds.size(), |frame| {
             let space = Path::rectangle(Point::new(0.0, 0.0), frame.size());
 
             let stars = Path::new(|path| {
@@ -151,7 +155,7 @@ impl<Message> canvas::Program<Message> for State {
             frame.fill(&stars, Color::WHITE);
         });
 
-        let system = self.system_cache.draw(bounds, |frame| {
+        let system = self.system_cache.draw(bounds.size(), |frame| {
             let center = frame.center();
 
             let sun = Path::circle(center, Self::SUN_RADIUS);
diff --git a/wgpu/src/widget/canvas.rs b/wgpu/src/widget/canvas.rs
index 0006ca8d..a5834330 100644
--- a/wgpu/src/widget/canvas.rs
+++ b/wgpu/src/widget/canvas.rs
@@ -9,8 +9,8 @@
 use crate::{Defaults, Primitive, Renderer};
 
 use iced_native::{
-    input::mouse, layout, Clipboard, Element, Hasher, Layout, Length,
-    MouseCursor, Point, Size, Vector, Widget,
+    layout, Clipboard, Element, Hasher, Layout, Length, MouseCursor, Point,
+    Size, Vector, Widget,
 };
 use std::hash::Hash;
 use std::marker::PhantomData;
@@ -18,6 +18,7 @@ use std::marker::PhantomData;
 pub mod path;
 
 mod cache;
+mod cursor;
 mod event;
 mod fill;
 mod frame;
@@ -27,6 +28,7 @@ mod stroke;
 mod text;
 
 pub use cache::Cache;
+pub use cursor::Cursor;
 pub use event::Event;
 pub use fill::Fill;
 pub use frame::Frame;
@@ -59,10 +61,10 @@ pub use text::Text;
 /// ```no_run
 /// # mod iced {
 /// #     pub use iced_wgpu::canvas;
-/// #     pub use iced_native::{Color, Size};
+/// #     pub use iced_native::{Color, Rectangle};
 /// # }
-/// use iced::canvas::{self, Cache, Canvas, Fill, Frame, Geometry, Path, Program};
-/// use iced::{Color, Size};
+/// use iced::canvas::{self, Canvas, Cursor, Fill, Frame, Geometry, Path, Program};
+/// use iced::{Color, Rectangle};
 ///
 /// // First, we define the data we need for drawing
 /// #[derive(Debug)]
@@ -72,9 +74,9 @@ pub use text::Text;
 ///
 /// // Then, we implement the `Program` trait
 /// impl Program<()> for Circle {
-///     fn draw(&self, bounds: Size) -> Vec<Geometry>{
+///     fn draw(&self, bounds: Rectangle, _cursor: Cursor) -> Vec<Geometry>{
 ///         // We prepare a new `Frame`
-///         let mut frame = Frame::new(bounds);
+///         let mut frame = Frame::new(bounds.size());
 ///
 ///         // We create a `Path` representing a simple circle
 ///         let circle = Path::circle(frame.center(), self.radius);
@@ -165,22 +167,16 @@ impl<Message, P: Program<Message>> Widget<Message, Renderer>
 
         let canvas_event = match event {
             iced_native::Event::Mouse(mouse_event) => {
-                Some(Event::Mouse(match mouse_event {
-                    mouse::Event::CursorMoved { .. } => {
-                        mouse::Event::CursorMoved {
-                            x: cursor_position.x - bounds.x,
-                            y: cursor_position.y - bounds.y,
-                        }
-                    }
-                    _ => mouse_event,
-                }))
+                Some(Event::Mouse(mouse_event))
             }
             _ => None,
         };
 
+        let cursor = Cursor::from_window_position(cursor_position);
+
         if let Some(canvas_event) = canvas_event {
             if let Some(message) =
-                self.program.update(canvas_event, bounds.size())
+                self.program.update(canvas_event, bounds, cursor)
             {
                 messages.push(message);
             }
@@ -192,11 +188,11 @@ impl<Message, P: Program<Message>> Widget<Message, Renderer>
         _renderer: &mut Renderer,
         _defaults: &Defaults,
         layout: Layout<'_>,
-        _cursor_position: Point,
+        cursor_position: Point,
     ) -> (Primitive, MouseCursor) {
         let bounds = layout.bounds();
         let translation = Vector::new(bounds.x, bounds.y);
-        let size = Size::new(bounds.width, bounds.height);
+        let cursor = Cursor::from_window_position(cursor_position);
 
         (
             Primitive::Translate {
@@ -204,13 +200,13 @@ impl<Message, P: Program<Message>> Widget<Message, Renderer>
                 content: Box::new(Primitive::Group {
                     primitives: self
                         .program
-                        .draw(size)
+                        .draw(bounds, cursor)
                         .into_iter()
                         .map(Geometry::into_primitive)
                         .collect(),
                 }),
             },
-            self.program.mouse_cursor(size),
+            self.program.mouse_cursor(bounds, cursor),
         )
     }
 
diff --git a/wgpu/src/widget/canvas/cursor.rs b/wgpu/src/widget/canvas/cursor.rs
new file mode 100644
index 00000000..a559782a
--- /dev/null
+++ b/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,
+        }
+    }
+}
diff --git a/wgpu/src/widget/canvas/program.rs b/wgpu/src/widget/canvas/program.rs
index 9e4aca89..f8e54514 100644
--- a/wgpu/src/widget/canvas/program.rs
+++ b/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)
     }
 }