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canvas canvas overlay for openseadragon

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Canvas Overlay for OpenSeadragon

An OpenSeadragon plugin that adds canvas overlay capability.

Compatible with OpenSeadragon 2.0.0 or greater.


To use, include the openseadragon-canvas-overlay.js file after openseadragon.js on your web page.

To add canvas overlay capability to your OpenSeadragon Viewer, call canvasOverlay(options) on it. It has two parameters: onRedraw - callback function that does the actual drawing, and clearBeforeRedraw (default as true): clear canvas before redrawing.

For example:

var overlay = this.viewer.canvasOverlay({
    onRedraw:function() {      
        overlay.context2d().fillStyle = "red";
        overlay.context2d().fillRect(0, 0, 500, 500);            

See demo or demo.html in github repository for an example of it in use.