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HTML5 Canvas - Rotation
HTML5 canvas provides rotate(angle) method which is used to rotate the canvas around the current origin.
This method only takes one parameter and that's the angle the canvas is rotated by. This is a clockwise rotation measured in radians.
Example
Following is a simple example which we are running two loops where first loop determines the number of rings, and the second determines the number of dots drawn in each ring.
<!DOCTYPE HTML> <html> <head> <style> #test { width: 100px; height:100px; margin: 0px auto; } </style> <script type = "text/javascript"> function drawShape() { // get the canvas element using the DOM var canvas = document.getElementById('mycanvas'); // Make sure we don't execute when canvas isn't supported if (canvas.getContext) { // use getContext to use the canvas for drawing var ctx = canvas.getContext('2d'); ctx.translate(100,100); for (i = 1; i<7; i++) { ctx.save(); ctx.fillStyle = 'rgb('+(51*i)+','+(200-51*i)+',0)'; for (j = 0; j < i*6; j++) { ctx.rotate(Math.PI*2/(i*6)); ctx.beginPath(); ctx.arc(0,i*12.5,5,0,Math.PI*2,true); ctx.fill(); } ctx.restore(); } } else { alert('You need Safari or Firefox 1.5+ to see this demo.'); } } </script> </head> <body id = "test" onload = "drawShape();"> <canvas id = "mycanvas" width = "400" height = "400"></canvas> </body> </html>
The above example would produce the following result −
html5_canvas.htm
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