Going full circle: could falling back to Flash solve IE’s lack of canvas support?
There is an interesting blog post* and demo code on Azarask explaining Flash Canvas as a solution for IE’s lack of support for Canvas:
How does FlashCanvas work?
FlashCanvas is modeled after ExplorerCanvas which means it is a turn-key solution for adding Canvas support to IE. You can code away, happily using open standards and then use FlashCanvas to forcefully and silently upgrade IE to also being standards compliant.
There are two main components in FlashCanvas: the base FlashCanvas.swf flash file (a mere 688 bytes), and the FlashCanvas.js wrapper. I’ve used the excellent swfobject.js to embed the Flash into the page.
The FlashCanvas.js file implements a fake-canvas object and converts all existing canvas element into a flash object. The javascript intercepts canvas commands and forwards them to the FlashCanvas.swf movie file using the ExternalInterface provided by the flash player. The flash movie clip then interprets the command and draws accordingly.
Aza originally thought that this would also solve the performance problems other fallbacks to VML have but found out that sadly enough this is not the case because of the lag between ActionScript and JavaScript via ExternalInterface.
Each call via the ExternalInterface is taking approximately 0.5 ms. Since we know the time it takes to call an actionscript method from javascript, we can deduce the amount of time it takes for Flash to render. For the example1.htm page it takes ~24 ms to render 20 anti-aliased lines. In Safari a call into actionscript takes roughly 0.4 ms — this is only the call time, it doesn’t include the time to render anything. For example1.htm a single “particle” calls actionscript 3 times with the commands: [lineStyle,moveTo,lineTo]; each particle takes 1.2 ms in JS-to-AS calls; to take 1 second to render the frame ~833 particles need to be rendered.
There are few more ideas in the comments to the article and this might be an interesting concept to take further. Somehow it seems ironic to go back to Flash to make IE render standards, but then again VML is proprietary, too.
