The getImageData function
The getImageData
function allows to retrieve an ImageData
object from your canvas
. This allows you to manipulate it as
you wish and then you can add it back onto the canvas
with the
putImageData
function
(reference page for the putImageData function).
You can pass it the X/Y/W/H that you want to fetch as arguments.
Arguments to the function
- The X coordinate at which to fetch data
- The Y coordinate at which to fetch data
- The width to fetch
- The height to fetch
An example
<script>
window.onload = function ()
{
var canvas = document.getElementById('cvs');
var context = canvas.getContext('2d');
// Fetches image data from the canvas
var imgData = context.getImageData(0,0,600,250);
}
</script>