refactoring

src/misc.rs

@@ -0,0 +1,30 @@
+use wasm_bindgen::prelude::*;
+
+pub type DrawResult<T> = Result<T, Box<dyn std::error::Error>>;
+
+/// Result of screen to chart coordinates conversion.
+#[wasm_bindgen]
+pub struct Point {
+    pub x: f32,
+    pub y: f32,
+}
+
+#[wasm_bindgen]
+impl Point {
+    pub fn new(x: f32, y: f32) -> Self { Self { x, y } }
+}
+
+#[wasm_bindgen]
+pub struct Chart {
+    pub(crate) convert: Box<dyn Fn((i32, i32)) -> Option<(f32, f32)>>,
+    pub(crate) area: f32,
+}
+
+#[wasm_bindgen]
+impl Chart {
+    pub fn get_area(&self) -> f32 { self.area }
+
+    pub fn coord(&self, x: i32, y: i32) -> Option<Point> {
+        (self.convert)((x, y)).map(|(x, y)| Point::new(x, y))
+    }
+}