migrate everything to typescript

bezier-2.ts

@@ -0,0 +1,65 @@
+import { Point, resizeCanvas, drawCircle, drawLine, cubicBezier } from "./common.js";
+
+function drawPoints(ctx: CanvasRenderingContext2D, points: Point[]) {
+    const [a, b, c, d] = points;
+    drawLine(ctx, a, b, 0xFF00FF);
+    drawLine(ctx, c, d, 0xFF00FF);
+    for (const p of points) {
+        drawCircle(ctx, p, 2, 0xFF00FF);
+    }
+}
+
+function drawCurve(ctx: CanvasRenderingContext2D, curve: Point[]) {
+    for (let i=0; i < curve.length - 1; ++i) {
+        drawLine(ctx, curve[i], curve[i+1], 0xFFFFFF);
+    }
+}
+
+
+function init() {
+    const canvas = document.getElementById("game") as HTMLCanvasElement | null;
+    if (!canvas) throw new Error("unable to get canvas HTML element");
+    const ctx = canvas.getContext("2d") as CanvasRenderingContext2D | null;
+    if (!ctx) throw new Error("unable to get canvas 2D context");
+
+    let selection: number | undefined = undefined;
+    let points: [Point, Point, Point, Point] = [
+        { x: 227, y: 434 },
+        { x: 341, y: 234 },
+        { x: 649, y: 255 },
+        { x: 765, y: 450 },
+    ];
+
+    resizeCanvas(ctx); // Init canvas
+    drawPoints(ctx, points);
+    const bezier = cubicBezier(...points);
+    drawCurve(ctx, bezier);
+
+    canvas.onmousedown = (evt) => {
+        const { clientX, clientY } = evt;
+        for (const p of points) {
+            if (Math.abs(p.x - clientX) < 10 && Math.abs(p.y - clientY) < 10) {
+                selection = points.indexOf(p);
+            }
+        }
+    };
+
+    canvas.onmousemove = (evt) => {
+        if (selection !== undefined) {
+            points[selection].x = evt.clientX;
+            points[selection].y = evt.clientY;
+            // redraw
+            ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
+            const bezier = cubicBezier(...points);
+            drawCurve(ctx, bezier);
+            drawPoints(ctx, points);
+        }
+    };
+
+    canvas.onmouseup = () => {
+        selection = undefined;
+    };
+}
+
+init();
+