Implement basic cursor availability

core/src/mouse/cursor.rs

@@ -0,0 +1,51 @@
+use crate::{Point, Rectangle, Vector};
+
+/// 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,
+}
+
+impl Cursor {
+    /// Returns the absolute position of the [`Cursor`], if available.
+    pub fn position(self) -> Option<Point> {
+        match self {
+            Cursor::Available(position) => Some(position),
+            Cursor::Unavailable => None,
+        }
+    }
+
+    /// Returns the absolute position of the [`Cursor`], if available and inside
+    /// the given bounds.
+    ///
+    /// If the [`Cursor`] is not over the provided bounds, this method will
+    /// return `None`.
+    pub fn position_over(self, bounds: &Rectangle) -> Option<Point> {
+        self.position().filter(|p| bounds.contains(*p))
+    }
+
+    /// 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`.
+    pub fn position_in(self, bounds: &Rectangle) -> Option<Point> {
+        self.position_over(bounds)
+            .map(|p| p - Vector::new(bounds.x, bounds.y))
+    }
+
+    /// Returns the relative position of the [`Cursor`] from the given origin,
+    /// if available.
+    pub fn position_from(self, origin: Point) -> Option<Point> {
+        self.position().map(|p| p - Vector::new(origin.x, origin.y))
+    }
+
+    /// Returns true if the [`Cursor`] is over the given `bounds`.
+    pub fn is_over(self, bounds: &Rectangle) -> bool {
+        self.position_over(bounds).is_some()
+    }
+}