Transformible coordinates are a board trait

src/board.rs

@@ -131,3 +131,41 @@ pub fn decode_png(buf: &[u8]) -> DynamicImage {
     reader.decode().unwrap()
 }
 
+fn lerp(v0: f32, v1: f32, t: f32) -> f32 {
+    v0 + t * (v1 - v0)
+}
+
+fn inv_lerp(v0: f32, v1: f32, a: f32) -> f32 {
+    (a - v0) / (v1 - v0)
+}
+
+pub trait CoordTransformer<I: CoordtypeConvertible> {
+    fn origin(&self) -> (I, I);
+    fn extremes(&self) -> (I, I);
+    fn to_coords(&self, x: I, y: I) -> (f32, f32) {
+	let (sx, sy) = self.origin();
+	let (ex, ey) = self.extremes();
+	(
+	    inv_lerp(sx.to_coordtype(), ex.to_coordtype(), x.to_coordtype()),
+	    inv_lerp(sy.to_coordtype(), ey.to_coordtype(), y.to_coordtype()),
+	)
+    }
+    fn from_coords(&self, x: f32, y: f32) -> (I, I) {
+	let (sx, sy) = self.origin();
+	let (ex, ey) = self.extremes(); 
+	(
+	    CoordtypeConvertible::from_coordtype(lerp(sx.to_coordtype(), ex.to_coordtype(), x)),
+	    CoordtypeConvertible::from_coordtype(lerp(sy.to_coordtype(), ey.to_coordtype(), y)),
+	)
+    }
+}
+
+pub trait CoordtypeConvertible {
+    fn to_coordtype(self) -> f32;
+    fn from_coordtype(coordtype: f32) -> Self;
+}
+
+impl CoordtypeConvertible for i32 {
+    fn to_coordtype(self) -> f32 { self as f32 }
+    fn from_coordtype(coordtype: f32) -> i32 { coordtype as i32 }
+}

src/main.rs

@@ -13,7 +13,7 @@ use std::sync::Mutex;
 
 mod board;
 use board::Board;
-use board::{ encode_png, write_board_to_file, read_board_from_file };
+use board::{ encode_png, write_board_to_file, read_board_from_file, CoordTransformer };
 
 //////////////////// Global State ////////////////////
 // Don't @ me...
@@ -133,35 +133,9 @@ mod dispatch {
     }
 }
 
-//////////////////// Utility Functions ////////////////////
-
-fn lerp(v0: f32, v1: f32, t: f32) -> f32 {
-    v0 + t * (v1 - v0)
-}
-
-fn inv_lerp(v0: f32, v1: f32, a: f32) -> f32 {
-    (a - v0) / (v1 - v0)
-}
-
-trait CoordTransformer {
-    fn to_coords(&self, x: i32, y: i32) -> (f32, f32);
-    fn from_coords(&self, x: f32, y: f32) -> (i32, i32);
-}
-
-impl CoordTransformer for frame::Frame {
-    fn to_coords(&self, x: i32, y: i32) -> (f32, f32) {
-	(
-	    inv_lerp(self.x() as f32, (self.x() + self.w()) as f32, x as f32),
-	    inv_lerp(self.y() as f32, (self.y() + self.h()) as f32, y as f32),
-	)
-    }
-
-    fn from_coords(&self, x: f32, y: f32) -> (i32, i32) {
-	(
-	    lerp(self.x() as f32, (self.x() + self.w()) as f32, x) as i32,
-	    lerp(self.y() as f32, (self.y() + self.h()) as f32, y) as i32,
-	)
-    }
+impl CoordTransformer<i32> for frame::Frame {
+    fn origin(&self) -> (i32, i32) { (self.x(), self.y()) }
+    fn extremes(&self) -> (i32, i32) { (self.x()+self.w(), self.y()+self.h()) }
 }
 
 //////////////////// App State ////////////////////