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<!DOCTYPE html> |
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<html> |
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<head> |
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<title>Custom Elements</title> |
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<script type="text/javascript" src="http://mbostock.github.com/d3/d3.js?2.3.2"></script> |
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<style type="text/css"> |
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body { |
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margin: 0; |
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} |
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</style> |
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</head> |
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<body> |
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<canvas id="container" width="960" height="500"></canvas> |
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<script type="text/javascript"> |
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var w = 960, |
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h = 500; |
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// creare a document fragment to draw "offline" |
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var sketchFrag = document.createDocumentFragment(); |
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var canvas = document.getElementById('container'); |
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var context = canvas.getContext("2d"); |
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var sketch = d3.select(sketchFrag).append("svg") |
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.attr("width", w) |
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.attr("height", h) |
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.call(custom); |
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// On each mouse move, create a circle that increases in size and fades away. |
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d3.select(canvas).on("mousemove", function() { |
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var circ = sketch.append("circle") |
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.attr("x", d3.event.offsetX) |
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.attr("y", d3.event.offsetY) |
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.attr("radius", 1) |
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.attr("strokeStyle", "red") |
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.transition() |
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.duration(2000) |
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.ease(Math.sqrt) |
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.attr("radius", 200) |
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.attr("strokeStyle", "white") |
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.remove(); |
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}); |
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function custom(selection) { |
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selection.each(function() { |
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var root = this; |
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// canvas.style.position = "absolute"; |
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// canvas.style.top = root.offsetTop + "px"; |
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// canvas.style.left = root.offsetLeft + "px"; |
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// It'd be nice to use DOM Mutation Events here instead. |
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// However, they appear to arrive irregularly, causing choppy animation. |
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d3.timer(redraw); |
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// Clear the canvas and then iterate over child elements. |
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function redraw() { |
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canvas.width = root.getAttribute("width"); |
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canvas.height = root.getAttribute("height"); |
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sketch.selectAll('circle') |
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.each(function(){ |
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var d = d3.select(this); |
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context.strokeStyle = d.attr("strokeStyle"); |
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context.beginPath(); |
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context.arc(d.attr("x"), d.attr("y"), d.attr("radius"), 0, 2 * Math.PI); |
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context.stroke(); |
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}); |
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} |
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}); |
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}; |
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</script> |
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</body> |
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</html> |
