Write documentation for the new canvas API

wgpu/src/widget/canvas/cursor.rs

@@ -1,8 +1,12 @@
 use iced_native::{Point, Rectangle};
 
+/// The mouse cursor state.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum Cursor {
+    /// The cursor has a defined position.
     Available(Point),
+
+    /// The cursor is currently unavailable (i.e. out of bounds or busy).
     Unavailable,
 }
 
@@ -17,6 +21,9 @@ impl Cursor {
         }
     }
 
+    /// Returns the absolute position of the [`Cursor`], if available.
+    ///
+    /// [`Cursor`]: enum.Cursor.html
     pub fn position(&self) -> Option<Point> {
         match self {
             Cursor::Available(position) => Some(*position),
@@ -24,6 +31,13 @@ impl Cursor {
         }
     }
 
+    /// Returns the relative position of the [`Cursor`] inside the given bounds,
+    /// if available.
+    ///
+    /// If the [`Cursor`] is not over the provided bounds, this method will
+    /// return `None`.
+    ///
+    /// [`Cursor`]: enum.Cursor.html
     pub fn position_in(&self, bounds: &Rectangle) -> Option<Point> {
         if self.is_over(bounds) {
             self.position_from(bounds.position())
@@ -32,6 +46,10 @@ impl Cursor {
         }
     }
 
+    /// Returns the relative position of the [`Cursor`] from the given origin,
+    /// if available.
+    ///
+    /// [`Cursor`]: enum.Cursor.html
     pub fn position_from(&self, origin: Point) -> Option<Point> {
         match self {
             Cursor::Available(position) => {
@@ -41,6 +59,10 @@ impl Cursor {
         }
     }
 
+    /// Returns whether the [`Cursor`] is currently over the provided bounds
+    /// or not.
+    ///
+    /// [`Cursor`]: enum.Cursor.html
     pub fn is_over(&self, bounds: &Rectangle) -> bool {
         match self {
             Cursor::Available(position) => bounds.contains(*position),