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canvas + chrome + content

bcrowder — Wed, 08 Apr 2009 18:04:37 +0000

I am writing an extension that attaches a div and a canvas to content pages, and in the process of trying to tune it for performance, I ran into bug 339587. I submitted a patch for that bug, but I ran into another problem, which is that my patch causes the ImageData to be wrapped (it becomes a SafeJSObjectWrapper), which means that subsequent putImageData calls are foiled; the object doesn’t look like an object anymore, and especially, the data member doesn’t look like an array, so eventually an exception is thrown. putImageData could be made more robust, but the cost might not be worth it… here’s the obvious workaround. You needn’t actually call createImageData, ever (at least not currently — this might change??); instead, you can build a JS object that looks and works precisely like an ImageData object in your own code. Since you’ll be setting the pixels yourself anyway, I suspect that creating your own image data is actually a tiny bit faster than using createImageData. Here’s what I did:

let imgData = { width: width, height: height }; imgData.data = new Array(width * height * 4); // make sure your array never needs to grow dynamically //.... initialization loop ....

This probably seems like an obvious workaround, but it might not be obvious to those who haven’t inspected the get/putImageData code.

million

bcrowder — Tue, 24 Jun 2008 19:03:05 +0000

This is a brilliant idea that rewards public school students with cell-phone air-time, credits for music purchases, etc., in exchange for educational performance, and is useful as an educational tool during classtime.

Here‘s a video about the project.

Did I mention it’s self-sustaining, and funded by advertising?

The Solar System Doesn’t Work as Well with IE

bcrowder — Thu, 29 Nov 2007 19:11:03 +0000

Seen in a Google Gadget, this morning:

Most installations of the Solar System don’t work as well with Internet Explorer. If you are still using IE this would be a good time to switch to the Firefox browser.

Deeply philosophical.

dtrace on Leopard

bcrowder — Mon, 29 Oct 2007 17:39:26 +0000

So good.

Not quite ready for primetime yet, but close enough to be useful for Mozilla/Firefox developers. Check it out.

Black Hat

bcrowder — Tue, 31 Jul 2007 05:11:33 +0000

This will be my first year at the Black Hat conference in Las Vegas. I’m exited. The fact that Jesse Ruderman is nervous, makes me nervous.

alas!

bcrowder — Tue, 13 Mar 2007 19:23:31 +0000

I really liked the Penn Jillette radio show. Too bad it’s been canceled.

Manipur, eh?

bcrowder — Mon, 12 Mar 2007 15:56:04 +0000

Apropos of nothing, this article from the Economist is a fascinating read.