Added Fun with HTML5 Canvas (wesbos#8)

JeffDess · JeffDess · commit 9ec17bfc84f1 · 2017-09-05T21:34:53.000-04:00
diff --git a/08 - Fun with HTML5 Canvas/index-START.html b/08 - Fun with HTML5 Canvas/index-START.html
@@ -7,6 +7,57 @@
 <body>
 <canvas id="draw" width="800" height="800"></canvas>
 <script>
+	const canvas = document.querySelector('#draw');
+	const ctx = canvas.getContext('2d');
+	let isDrawing = false;
+	let isGrowing = true;
+	let lastX = 0;
+	let lastY = 0;
+	let hue = 0;
+
+  // Canvas initialization
+	canvas.width = window.innerWidth;
+	canvas.height = window.innerHeight;
+	ctx.strokeStyle = '#BADA55';
+	ctx.lineJoin = 'round';
+	ctx.lineCap = 'round';
+	ctx.globalCompositeOperation = 'darken';
+
+	function draw(e) {
+		if(!isDrawing) return;
+
+		ctx.strokeStyle = `hsl(${hue}, 100%, 50%)`;
+
+		// Start
+		ctx.beginPath();
+		ctx.moveTo(lastX, lastY);
+
+		// Draw
+		ctx.lineTo(e.offsetX, e.offsetY);
+		ctx.stroke();
+		[lastX, lastY] = [e.offsetX, e.offsetY];
+		
+		// Change color
+		if (hue > 360) hue = 0;
+		hue++;
+
+		// Change brush size
+		if (ctx.lineWidth >= 100 || ctx.lineWidth <= 1) isGrowing = !isGrowing; 
+
+		if (isGrowing){
+			ctx.lineWidth++;
+		} else {
+			ctx.lineWidth--;
+		}
+	}
+
+	canvas.addEventListener('mousemove', draw);
+	canvas.addEventListener('mouseup', () => isDrawing = false);
+	canvas.addEventListener('mouseout', () => isDrawing = false);
+	canvas.addEventListener('mousedown', (e) => {
+		isDrawing = true;
+		[lastX,lastY] = [e.offsetX, e.offsetY];
+	});
 </script>
 
 <style>
