A little helper object to allow for saving of a canvas tag to an image. It uses a server side script to save the image to avoid things like not being able to set a filename, and popping up scary looking dialogue boxes. For more in-depth explanation and example, see: https://greenethumb.com/article/1429/user-friendly-image-saving-from-the-canvas/

quick impl example:

<canvas id='drawhere' width='610' height='350'></canvas>
<script src="./canvassaver.js">
<script>
var cnvs = document.getElementById('drawhere');
var cs = new CanvasSaver('./saveme.php')
var btn = cs.generateButton('save an image!', cnvs, 'myimage');
document.appendChild(btn);
</script>