[emath] Add Pos2::zero() and Rect::clamp(point)

emath/src/pos2.rs

@@ -35,6 +35,13 @@ impl From<&[f32; 2]> for Pos2 {
 }
 
 impl Pos2 {
+    /// The zero position, the origin.
+    /// The top left corner in a GUI.
+    /// Same as `Pos2::default()`.
+    pub const fn zero() -> Self {
+        Self { x: 0.0, y: 0.0 }
+    }
+
     pub const fn new(x: f32, y: f32) -> Self {
         Self { x, y }
     }

emath/src/rect.rs

@@ -131,6 +131,14 @@ impl Rect {
             && p.y <= self.min.y + self.size().y
     }
 
+    /// Return the given points clamped to be inside the rectangle
+    #[must_use]
+    pub fn clamp(&self, mut p: Pos2) -> Pos2 {
+        p.x = clamp(p.x, self.x_range());
+        p.y = clamp(p.y, self.y_range());
+        p
+    }
+
     pub fn extend_with(&mut self, p: Pos2) {
         self.min = self.min.min(p);
         self.max = self.max.max(p);