Image Rotate with CANVAS

Benoit Asselin Jul 11, 2008

General

CANVAS is a new HTML element which can be used to draw graphics using JavaScript. This script will rotate an image a varying amount of degrees: 90, 180, -90, and back to 0. Can be used in many different ways.

rotate:

Notes

Created by: Benoit Asselin
Web Site: http://www.ab-d.fr

Source Code

Paste this source code into the designated areas.

External file

Paste this code into an external JavaScript file named: imgRotateCanvas.js

/* This script and many more are available free online at
The JavaScript Source!! http://www.javascriptsource.com
Created by: Benoit Asselin | http://www.ab-d.fr */

function rotate(p_deg) {
	if(document.getElementById('canvas')) {
		/*
		Ok!: Firefox 2, Safari 3, Opera 9.5b2
		No: Opera 9.27
		*/
		var image = document.getElementById('image');
		var canvas = document.getElementById('canvas');
		var canvasContext = canvas.getContext('2d');
		
		switch(p_deg) {
			default :
			case 0 :
				canvas.setAttribute('width', image.width);
				canvas.setAttribute('height', image.height);
				canvasContext.rotate(p_deg * Math.PI / 180);
				canvasContext.drawImage(image, 0, 0);
				break;
			case 90 :
				canvas.setAttribute('width', image.height);
				canvas.setAttribute('height', image.width);
				canvasContext.rotate(p_deg * Math.PI / 180);
				canvasContext.drawImage(image, 0, -image.height);
				break;
			case 180 :
				canvas.setAttribute('width', image.width);
				canvas.setAttribute('height', image.height);
				canvasContext.rotate(p_deg * Math.PI / 180);
				canvasContext.drawImage(image, -image.width, -image.height);
				break;
			case 270 :
			case -90 :
				canvas.setAttribute('width', image.height);
				canvas.setAttribute('height', image.width);
				canvasContext.rotate(p_deg * Math.PI / 180);
				canvasContext.drawImage(image, -image.width, 0);
				break;
		};
		
	} else {
		/*
		Ok!: MSIE 6 et 7
		*/
		var image = document.getElementById('image');
		switch(p_deg) {
			default :
			case 0 :
				image.style.filter = 'progid:DXImageTransform.Microsoft.BasicImage(rotation=0)';
				break;
			case 90 :
				image.style.filter = 'progid:DXImageTransform.Microsoft.BasicImage(rotation=1)';
				break;
			case 180 :
				image.style.filter = 'progid:DXImageTransform.Microsoft.BasicImage(rotation=2)';
				break;
			case 270 :
			case -90 :
				image.style.filter = 'progid:DXImageTransform.Microsoft.BasicImage(rotation=3)';
				break;
		};
		
	};
};

// Multiple onload function created by: Simon Willison
// http://simonwillison.net/2004/May/26/addLoadEvent/
function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}

addLoadEvent(function() {
	var image = document.getElementById('image');
	var canvas = document.getElementById('canvas');
	if(canvas.getContext) {
		image.style.visibility = 'hidden';
		image.style.position = 'absolute';
	} else {
		canvas.parentNode.removeChild(canvas);
	};
	
	rotate(0);
});

Head

Paste this code into the HEAD section of your HTML document.


<script type="text/javascript" src="imgRotateCanvas.js"></script>

Body

Paste this code into the BODY section of your HTML document


<p>
	rotate:
	<input type="button" value="0°" onclick="rotate(0);">
	<input type="button" value="90°" onclick="rotate(90);">
	<input type="button" value="180°" onclick="rotate(180);">
	<input type="button" value="-90°" onclick="rotate(-90);">
</p>
<p>
	<img id="image" src="http://www.javascriptsource.com//img/headerlogo.gif" alt="">
	<canvas id="canvas"></canvas>
</p>

Leave a Response

(3 comments)

Search a long time for a thing like that.[br /]Thanks a lot!

markus Oct 5, 2008

That's very Good.

Dongmook Yi Jul 13, 2008

that's just cool!

Evgeniy Jul 10, 2008

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