implement mint conversions (#352)

* Implement mint conversions

Implement conversions for [mint](https://docs.rs/mint) (math interoperability standard types).

- `impl {From, Into}<mint::Point2> for Pos2`
- `impl {From, Into}<mint::Vector2> for Vec2`

* Forward `mint` feature: egui -> epaint -> emath

egui/Cargo.toml

@@ -37,5 +37,7 @@ persistence = ["serde", "epaint/persistence", "ron"]
 single_threaded = ["epaint/single_threaded"]
 multi_threaded = ["epaint/multi_threaded"]
 
+mint = ["epaint/mint"]
+
 [dev-dependencies]
-serde_json = "1"
+serde_json = "1"

emath/Cargo.toml

@@ -20,6 +20,7 @@ include = [
 [lib]
 
 [dependencies]
+mint = { version = "0.5.6", optional = true }
 serde = { version = "1", features = ["derive"], optional = true }
 
 [features]

emath/src/pos2.rs

@@ -84,6 +84,23 @@ impl From<&Pos2> for (f32, f32) {
     }
 }
 
+// ----------------------------------------------------------------------------
+// Mint compatibility and convenience conversions
+
+#[cfg(feature = "mint")]
+impl From<mint::Point2<f32>> for Pos2 {
+    fn from(v: mint::Point2<f32>) -> Self {
+        Self::new(v.x, v.y)
+    }
+}
+
+#[cfg(feature = "mint")]
+impl From<Pos2> for mint::Point2<f32> {
+    fn from(v: Pos2) -> Self {
+        Self { x: v.x, y: v.y }
+    }
+}
+
 // ----------------------------------------------------------------------------
 
 impl Pos2 {

emath/src/vec2.rs

@@ -81,6 +81,23 @@ impl From<&Vec2> for (f32, f32) {
     }
 }
 
+// ----------------------------------------------------------------------------
+// Mint compatibility and convenience conversions
+
+#[cfg(feature = "mint")]
+impl From<mint::Vector2<f32>> for Vec2 {
+    fn from(v: mint::Vector2<f32>) -> Self {
+        Self::new(v.x, v.y)
+    }
+}
+
+#[cfg(feature = "mint")]
+impl From<Vec2> for mint::Vector2<f32> {
+    fn from(v: Vec2) -> Self {
+        Self { x: v.x, y: v.y }
+    }
+}
+
 // ----------------------------------------------------------------------------
 
 impl Vec2 {

epaint/Cargo.toml

@@ -43,3 +43,5 @@ single_threaded = ["atomic_refcell"]
 
 # Only needed if you plan to use the same fonts from multiple threads.
 multi_threaded = ["parking_lot"]
+
+mint = ["emath/mint"]