Problem with HTML5 Canvas drawImage on Windows 7, but only in Firefox

I have a problem with a program I am developing (you can see it at )

The galaxy viewer draws stars on 6 different layers. The back layers work fine (with a simple hit command). The top 3 layers use the drawImage () function to take the saved image and draw it onto the canvas (using the starGradDraw and starGradDraw2 functions).

These images were created by another function when the program was first executed and stored in an object variable (basically just a buffer).

Everything works correctly on my home computer, my laptop, my wife’s computer and just about every other machine I tested this on (or had friends).

When I tried to open it in Firefox 10.0.2 on my work computer (the same version I use at home), the first three layers of stars are blank. The only difference I can think of is that none of my home computers use a 64-bit operating system, or in particular Windows 7.

Everything else still works fine in the program and firebug doesn't throw any errors. It's just not drawing images (or stopping the program). I'm really not sure what to try next.

Any ideas?

(I can paste in the code if you like, but the program is over a thousand lines long, and I don't know where the problem might be or how it might only happen on this machine.)


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After quite a lot of research and searching for bugs, I found that this problem is a bug of Firefox itself.

Apparently, in the current version with 2-D GPU hardware acceleration enabled, Firefox does not save correct gradients correctly when drawn directly onto the buffer canvas (off-screen only).

Disabling hardware acceleration allows the browser to handle commands correctly.

A bug report has been submitted and hopefully the issue will be fixed.



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