Day 08 Fun with HTML Canvas

bweisberg · bweisberg · commit 2b5b3b8c187e · 2017-01-04T16:39:26.000-08:00
What's this hsl color syntax?
Multiple assignment in ES6 with [x, y] = [100, 90]
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>
+console.log('hi');
+const canvas = document.querySelector('#draw');
+const ctx = canvas.getContext('2d');
+canvas.width = window.innerWidth;
+canvas.height = window.innerHeight;
+ctx.strokeStyle = '#BADA55';
+ctx.lineJoin = 'round';
+ctx.lineCap = 'round';
+ctx.lineWidth = 100;
+ctx.globalCompositeOperation = 'multiply';
+
+let isDrawing = false;
+let lastX = 0;
+let lastY = 0;
+let hue = 0;
+let direction = true;
+
+function draw(e) {
+  if(!isDrawing) return; // stop the function from running when they are not moused
+  console.log(e);
+  ctx.strokeStyle = `hsl(${hue}, 100%, 50%)`
+  ctx.beginPath();
+  //start from
+  ctx.moveTo(lastX, lastY);
+  //go to
+  ctx.lineTo(e.offsetX, e.offsetY);
+  ctx.stroke();
+  [lastX, lastY] = [e.offsetX, e.offsetY];
+  hue++;
+  if (hue >= 360) {
+    hue = 0;
+  }
+
+  if (ctx.lineWidth >= 100 || ctx.lineWidth <= 1) {
+    direction = !direction;
+  }
+  if (direction) {
+    ctx.lineWidth++;
+  } else {
+    ctx.lineWidth--;
+  }
+}
+
+canvas.addEventListener('mousedown', (e) => {
+  isDrawing = true;
+  [lastX, lastY] = [e.offsetX, e.offsetY];
+});
+
+canvas.addEventListener('mousemove', draw);
+canvas.addEventListener('mouseup', () => isDrawing = false);
+canvas.addEventListener('mouseout', () => isDrawing = false);
 </script>
 
 <style>
