58 lines
2.1 KiB
HTML
58 lines
2.1 KiB
HTML
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<!doctype html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>Spray Paint</title>
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<link rel="stylesheet" href="../include/style.css">
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</head>
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<body>
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<header>
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Example from <a href="http://amzn.com/1430236655?tag=html5anim-20"><em>Foundation HTML5 Animation with JavaScript</em></a>
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</header>
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<canvas id="canvas" width="400" height="400"></canvas>
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<aside>Click and draw with the mouse.</aside>
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<script src="../include/utils.js"></script>
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<script>
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window.onload = function () {
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var canvas = document.getElementById('canvas'),
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context = canvas.getContext('2d'),
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mouse = utils.captureMouse(canvas),
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imagedata = context.getImageData(0, 0, canvas.width, canvas.height),
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pixels = imagedata.data,
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brush_size = 25,
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brush_density = 50,
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brush_color;
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canvas.addEventListener('mousedown', function () {
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brush_color = utils.parseColor(Math.random() * 0xffffff, true); //to number
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canvas.addEventListener('mousemove', onMouseMove, false);
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}, false);
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canvas.addEventListener('mouseup', function () {
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canvas.removeEventListener('mousemove', onMouseMove, false);
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}, false);
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function onMouseMove () {
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//loop over each brush bristle
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for (var i = 0; i < brush_density; i++) {
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var angle = Math.random() * Math.PI * 2,
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radius = Math.random() * brush_size,
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xpos = (mouse.x + Math.cos(angle) * radius) | 0,
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ypos = (mouse.y + Math.sin(angle) * radius) | 0,
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offset = (xpos + ypos * imagedata.width) * 4; //array index of canvas coordinate
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//set the color of a pixel using its component colors: r,g,b,a (0-255)
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pixels[offset] = brush_color >> 16 & 0xff; //red
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pixels[offset + 1] = brush_color >> 8 & 0xff; //green
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pixels[offset + 2] = brush_color & 0xff; //blue
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pixels[offset + 3] = 255; //alpha
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}
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context.putImageData(imagedata, 0, 0);
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}
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};
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</script>
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</body>
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</html>
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