Created
June 17, 2014 22:03
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Animate Canvas Arc
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| <!DOCTYPE HTML> | |
| <html> | |
| <head> | |
| <style> | |
| body { | |
| margin: 0px; | |
| padding: 0px; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <canvas id="myCanvas" width="578" height="250"></canvas> | |
| <script> | |
| var canvas = document.getElementById('myCanvas'); | |
| var context = canvas.getContext('2d'); | |
| var TIMER_LENGTH = 10000; // 10 seconds | |
| var interval = TIMER_LENGTH / 360; //miliseconds per degree increment | |
| var startTime; | |
| function step(timestamp) { | |
| startTime || (startTime = timestamp); | |
| var x = canvas.width / 2; | |
| var y = canvas.height / 2; | |
| var radius = 75; | |
| var endDegrees = (timestamp - startTime) / interval; | |
| var startAngle = getRadians(0); | |
| var endAngle = getRadians(endDegrees) | |
| // Animate the canvas | |
| context.beginPath(); | |
| context.arc(x, y, radius, startAngle, endAngle, counterClockwise=false); | |
| context.lineWidth = 15; | |
| // line color | |
| context.strokeStyle = 'black'; | |
| context.stroke(); | |
| // Rerun the step function | |
| requestAnimationFrame(step) | |
| } | |
| // Run the step function | |
| requestAnimationFrame(step) | |
| function getRadians(degrees) { | |
| degrees = degrees - 90 | |
| return degrees * (Math.PI / 180) | |
| } | |
| </script> | |
| </body> | |
| </html> |
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