A simple example of HTML5's canvas element, showing a bilinear color gradient.
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August 29, 2015 14:03
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Canvas gradient
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| `// noprotect` | |
| canvas = d3.select('canvas') | |
| width = canvas.node().getBoundingClientRect().width | |
| height = canvas.node().getBoundingClientRect().height | |
| ctx = canvas.node().getContext('2d') | |
| image = ctx.createImageData(width, height) | |
| for x in [0...width] | |
| for y in [0...height] | |
| i = (y*width+x)*4 | |
| [r,g,b,a] = [i+0,i+1,i+2,i+3] | |
| image.data[r] = x/width*255 | |
| image.data[g] = 0 | |
| image.data[b] = y/height*255 | |
| image.data[a] = 255 | |
| ctx.putImageData(image,0,0) |
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <meta name="description" content="Canvas gradient" /> | |
| <title>Canvas gradient</title> | |
| <link rel="stylesheet" href="index.css"> | |
| <script src="http://d3js.org/d3.v3.min.js"></script> | |
| </head> | |
| <body> | |
| <canvas width="960" height="500"></canvas> | |
| <script src="index.js"></script> | |
| </body> | |
| </html> |
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| (function() { | |
| // noprotect; | |
| var a, b, canvas, ctx, g, height, i, image, r, width, x, y, _i, _j, _ref; | |
| canvas = d3.select('canvas'); | |
| width = canvas.node().getBoundingClientRect().width; | |
| height = canvas.node().getBoundingClientRect().height; | |
| ctx = canvas.node().getContext('2d'); | |
| image = ctx.createImageData(width, height); | |
| for (x = _i = 0; 0 <= width ? _i < width : _i > width; x = 0 <= width ? ++_i : --_i) { | |
| for (y = _j = 0; 0 <= height ? _j < height : _j > height; y = 0 <= height ? ++_j : --_j) { | |
| i = (y * width + x) * 4; | |
| _ref = [i + 0, i + 1, i + 2, i + 3], r = _ref[0], g = _ref[1], b = _ref[2], a = _ref[3]; | |
| image.data[r] = x / width * 255; | |
| image.data[g] = 0; | |
| image.data[b] = y / height * 255; | |
| image.data[a] = 255; | |
| } | |
| } | |
| ctx.putImageData(image, 0, 0); | |
| }).call(this); |
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