add triangle shape

src/ellipse.rs

@@ -9,7 +9,7 @@ use core::{
     ops::{Add, Mul, Sub},
 };
 
-use crate::{Affine, Arc, ArcAppendIter, Circle, PathEl, Point, Rect, Shape, Size, Vec2};
+use crate::{Affine, Arc, ArcAppendIter, Circle, PathEl, Point, Rect, Shape, Size, Triangle, Vec2};
 
 #[cfg(not(feature = "std"))]
 use crate::common::FloatFuncs;
@@ -58,6 +58,24 @@ impl Ellipse {
         Ellipse::private_new(center, width, height, 0.0)
     }
 
+    // TODO: this returns the largest circle not ellipse
+    /// Returns the largest ellipse that can be bounded by this [`Triangle`].
+    ///
+    /// This ellipse is always axis-aligned; to apply rotation you can call
+    /// [`with_rotation`] with the result.
+    ///
+    /// [`with_rotation`]: Ellipse::with_rotation
+    #[inline]
+    pub fn from_triangle(triangle: Triangle) -> Self {
+        let radius = triangle.radius();
+        Ellipse::private_new(
+            triangle.centroid().to_vec2(),
+            radius / 2.0,
+            radius / 2.0,
+            0.0,
+        )
+    }
+
     /// Create an ellipse from an affine transformation of the unit circle.
     #[inline]
     pub fn from_affine(affine: Affine) -> Self {

src/lib.rs

@@ -112,6 +112,7 @@ mod stroke;
 #[cfg(feature = "std")]
 mod svg;
 mod translate_scale;
+mod triangle;
 mod vec2;
 
 pub use crate::affine::*;
@@ -136,4 +137,5 @@ pub use crate::stroke::*;
 #[cfg(feature = "std")]
 pub use crate::svg::*;
 pub use crate::translate_scale::*;
+pub use crate::triangle::*;
 pub use crate::vec2::*;