What is the getCSSCanvasContext() method of an HTML5 element?

问题

What is the getCSSCanvasContext() method? I saw it in Chrome’s debuging console, but I cannot find any decent documentation for it.

Does it mean we can draw using canvas commands on any element?

回答1:

The method is implemented in WebKit (meaning you can also use it in Safari) and returns an object that lets you draw into a CSS image. See this blog post for an example:

In the latest nightlies, you can try out a new feature: the ability to specify named image buffers in CSS and then to draw into them programmatically from JavaScript. Here’s how it works.

background: -webkit-canvas(mycanvas);

Instead of specifying an image URL, you specify a canvas and an identifier to use for that canvas. The following new API on documents can then be used to obtain a drawing context for that canvas.

CanvasRenderingContext getCSSCanvasContext(in DOMString contextType, in DOMString identifier, in long width, in long height);

回答2:

also don't use ctx.clearRect(0, 0, w, h); for IE9 - it doesn't work after this code if you try to draw something after clearRect() you will get empty canvas anyway

来源：https://stackoverflow.com/questions/3433010/what-is-the-getcsscanvascontext-method-of-an-html5-element