I want to crop several images in a page using HTML5's canvas
tag and JavaScript. The problem is that the page shows just one of the images.
What should I do? The code I tried is below:
<canvas id="myCanvas" width="300" height="300"></canvas>
<canvas id="myCanvas" width="300" height="300"></canvas>
<canvas id="myCanvas" width="300" height="300"></canvas>
<script>
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
var imageObj = new Image();
imageObj.onload = function() {
// draw cropped image
var sourceX = 0;
var sourceY = 0;
var sourceWidth = 200;
var sourceHeight = 150;
var destWidth = sourceWidth;
var destHeight = sourceHeight;
var destX = canvas.width / 2 - destWidth / 2;
var destY = canvas.height / 2 - destHeight / 2;
context.drawImage(imageObj, sourceX, sourceY, sourceWidth, sourceHeight, destX, destY, destWidth, destHeight);
};
imageObj.src ='http://static.adzerk.net/Advertisers/3478c54721cd466fb6f7d3afe16e97d4.gif';
</script>
The Fiddle: http://jsfiddle.net/soheilyou/54VTh/
Just as Some Guy said, you are using the same id
for each canvas -- that's a no-no. Try giving each one a unique id
or using a class instead.
Then, it's just a matter of grabbing the elements one by one -- which you could do with JavaScript or perhaps more easily with jQuery (below).
Check out this updated Fiddle or see this JavaScript snippet:
var canvases = $('.myCanvas');
$(canvases).each(function () {
var canvas = $(this).get(0); //Grab the canvas node from the jQuery container.
var context = canvas.getContext('2d');
var imageObj = new Image();
imageObj.onload = function () {
var sourceX = 0;
var sourceY = 0;
var sourceWidth = 200;
var sourceHeight = 150;
var destWidth = sourceWidth;
var destHeight = sourceHeight;
var destX = canvas.width / 2 - destWidth / 2;
var destY = canvas.height / 2 - destHeight / 2;
context.drawImage(imageObj, sourceX, sourceY,
sourceWidth, sourceHeight, destX,
destY, destWidth, destHeight);
};
imageObj.src = 'path/to/your/image.png';
});