Add docs to wasm-demo and rustfmt it

Author: TatriX

examples/wasm-demo/src/func_plot.rs

@@ -1,9 +1,9 @@
-use plotters::prelude::*;
 use crate::DrawResult;
+use plotters::prelude::*;
 
 /// Draw power function f(x) = x^power.
 pub fn draw(canvas_id: &str, power: i32) -> DrawResult<impl Fn((i32, i32)) -> Option<(f32, f32)>> {
-    let backend = CanvasBackend::new(canvas_id).unwrap();
+    let backend = CanvasBackend::new(canvas_id).expect("cannot find canvas");
     let root = backend.into_drawing_area();
     let font: FontDesc = ("sans-serif", 20.0).into();
 

examples/wasm-demo/src/lib.rs

@@ -10,11 +10,14 @@ static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;
 /// Type alias for the result of a drawing function.
 pub type DrawResult<T> = Result<T, Box<dyn std::error::Error>>;
 
+/// Type used on the JS side to convert screen coordinates to chart
+/// coordinates.
 #[wasm_bindgen]
 pub struct Chart {
     convert: Box<dyn Fn((i32, i32)) -> Option<(f64, f64)>>,
 }
 
+/// Result of screen to chart coordinates conversion.
 #[wasm_bindgen]
 pub struct Point {
     pub x: f64,
@@ -23,21 +26,27 @@ pub struct Point {
 
 #[wasm_bindgen]
 impl Chart {
+    /// Draw provided power function on the canvas element using it's id.
+    /// Return `Chart` struct suitable for coordinate conversion.
     pub fn power(canvas_id: &str, power: i32) -> Result<Chart, JsValue> {
         let map_coord = func_plot::draw(canvas_id, power).map_err(|err| err.to_string())?;
-        Ok(Chart{convert: Box::new(move |coord| {
-            map_coord(coord).map(|(x, y)| (x.into(), y.into()))
-        })})
+        Ok(Chart {
+            convert: Box::new(move |coord| map_coord(coord).map(|(x, y)| (x.into(), y.into()))),
+        })
     }
 
+    /// Draw Mandelbrot set on the provided canvas element.
+    /// Return `Chart` struct suitable for coordinate conversion.
     pub fn mandelbrot(canvas: HtmlCanvasElement) -> Result<Chart, JsValue> {
         let map_coord = mandelbrot::draw(canvas).map_err(|err| err.to_string())?;
-        Ok(Chart{convert: Box::new(map_coord)})
+        Ok(Chart {
+            convert: Box::new(map_coord),
+        })
     }
 
     /// This function can be used to convert screen coordinates to
-    /// graph coordinates.
+    /// chart coordinates.
     pub fn coord(&self, x: i32, y: i32) -> Option<Point> {
-        (self.convert)((x, y)).map(|(x, y)| Point{x, y})
+        (self.convert)((x, y)).map(|(x, y)| Point { x, y })
     }
 }

examples/wasm-demo/src/mandelbrot.rs

@@ -1,7 +1,7 @@
+use crate::DrawResult;
 use plotters::prelude::*;
 use std::ops::Range;
 use web_sys::HtmlCanvasElement;
-use crate::DrawResult;
 
 /// Draw Mandelbrot set
 pub fn draw(element: HtmlCanvasElement) -> DrawResult<impl Fn((i32, i32)) -> Option<(f64, f64)>> {

examples/wasm-demo/www/index.js

@@ -1,7 +1,6 @@
 import { Chart, drawPower } from "wasm-demo";
 
 const canvas = document.getElementById("canvas");
-const ctx = canvas.getContext("2d");
 const coord = document.getElementById("coord");
 const plotType = document.getElementById("plot-type");
 const status = document.getElementById("status");
@@ -14,7 +13,7 @@ function main() {
     setupCanvas();
 }
 
-/** Add event listeners */
+/** Add event listeners. */
 function setupUI() {
     status.innerText = "WebAssembly loaded!";
     plotType.addEventListener("change", updatePlot);
@@ -31,29 +30,29 @@ function setupCanvas() {
     canvas.style.height = size / aspectRatio + "px";
     canvas.width = size * dpr;
     canvas.height = size / aspectRatio * dpr;
-    ctx.scale(dpr, dpr);
+    canvas.getContext("2d").scale(dpr, dpr);
     updatePlot();
 }
 
-/** Update displayed coordinates */
+/** Update displayed coordinates. */
 function onMouseMove(event) {
-	if (chart) {
+    if (chart) {
         const point = chart.coord(event.offsetX, event.offsetY);
         coord.innerText = (point)
             ? `(${point.x.toFixed(3)}, ${point.y.toFixed(3)})`
             : "Mouse pointer is out of range";
     }
 }
 
-/** Redraw currently selected plot */
+/** Redraw currently selected plot. */
 function updatePlot() {
     const selected = plotType.selectedOptions[0];
-	status.innerText = `Rendering ${selected.innerText}...`;
-	chart = undefined;
-	const start = performance.now();
+    status.innerText = `Rendering ${selected.innerText}...`;
+    chart = undefined;
+    const start = performance.now();
     chart = (selected.value == "mandelbrot")
         ? Chart.mandelbrot(canvas)
         : Chart.power("canvas", Number(selected.value));
-	const end = performance.now();
-	status.innerText = `Rendered ${selected.innerText} in ${Math.ceil(end - start)}ms`;
+    const end = performance.now();
+    status.innerText = `Rendered ${selected.innerText} in ${Math.ceil(end - start)}ms`;
 }