HTML5 Canvas - Animations
HTML5 canvas provides necessary methods to draw an image and erase it completely. We can take Javascript help to simulate good animation over a HTML5 canvas.
Following are the two important Javascript methods which would be used to animate an image on a canvas −
Sr.No. | Method and Description |
---|---|
1 | setInterval(callback, time); This method repeatedly executes the supplied code after a given timemilliseconds. |
2 | setTimeout(callback, time); This method executes the supplied code only once after a given time milliseconds. |
Example
Following is a simple example which would rotate a small image repeatedly −
Live Demo<!DOCTYPE HTML> <html> <head> <script type = "text/javascript"> var pattern = new Image(); function animate() { pattern.src = '/html5/images/pattern.jpg'; setInterval(drawShape, 100); } 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.fillStyle = 'rgba(0,0,0,0.4)'; ctx.strokeStyle = 'rgba(0,153,255,0.4)'; ctx.save(); ctx.translate(150,150); var time = new Date(); ctx.rotate( ((2*Math.PI)/6)*time.getSeconds() + ( (2*Math.PI)/6000)*time.getMilliseconds() ); ctx.translate(0,28.5); ctx.drawImage(pattern,-3.5,-3.5); ctx.restore(); } else { alert('You need Safari or Firefox 1.5+ to see this demo.'); } } </script> </head> <body onload = "animate();"> <canvas id = "mycanvas" width = "400" height = "400"></canvas> </body> </html>
The above example would produce the following result −