init

src/lib.rs

@@ -0,0 +1,48 @@
+use wasm_bindgen::prelude::*;
+use web_sys::HtmlCanvasElement;
+mod func_plot;
+use meval::Expr;
+
+#[global_allocator]
+static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;
+
+pub type DrawResult<T> = Result<T, Box<dyn std::error::Error>>;
+
+#[wasm_bindgen]
+pub struct Chart {
+    convert: Box<dyn Fn((i32, i32)) -> Option<(f32, f32)>>,
+    area: f32
+}
+
+/// Result of screen to chart coordinates conversion.
+#[wasm_bindgen]
+pub struct Point {
+    pub x: f32,
+    pub y: f32,
+}
+
+#[wasm_bindgen]
+impl Chart {
+    pub fn draw(canvas: HtmlCanvasElement, func: &str, minX: f32, maxX: f32, minY: f32, maxY: f32, num_interval: usize, resolution: i32) -> Result<Chart, JsValue> {
+        let output = func_plot::draw(canvas, func, minX, maxX, minY, maxY, num_interval, resolution).map_err(|err| err.to_string())?;
+        let map_coord = output.0;
+        Ok(Chart {
+            convert: Box::new(move |coord| map_coord(coord).map(|(x, y)| (x.into(), y.into()))),
+            area: output.1,
+        })
+    }
+
+    pub fn get_area(&self) -> Result<f32, JsValue> {
+        return Ok(self.area);
+    }
+
+    // Does actual calculation of antiderivative
+    // pub fn actual_area(power: f32, minX: f32, maxX: f32) -> Result<f32, JsValue> {
+    //     let newpower = power + 1.0;
+    //     return Ok((maxX.powf(newpower as f32)/newpower) - (minX.powf(newpower as f32)/newpower));
+    // }
+
+    pub fn coord(&self, x: i32, y: i32) -> Option<Point> {
+        (self.convert)((x, y)).map(|(x, y)| Point { x, y })
+    }
+}