This is a followup to bug 672646. In that bug, the radial gradient was opaque. This fixed the problems in web content, but when painting onto glass in the Firefox toolbar there is still a bug. The gradient is no longer opaque, but it is more opaque than the linear gradient it matches up with. Screenshot attached. This is a Windows-only regression from Azure. Disabling azure via pref fixes the issue.

Here is a testcase extension: install it and then run Firefox with -chrome chrome://azuretestcase/content/

I can't get this test case to work for me. When I launch with -chrome chrome://azuretestcase/content/ I get no windows at all.

Whoops, it was chrome://azure-testcase/content/

This should be easy to fix again. We're accidentally squaring the alpha.

We were accidentally squaring alpha. This patch avoids doing so and fixes the problem. I have a reftest that I'll upload later.

Comment on attachment 548626 [details] [diff] [review] Fix premultiplying to only premultiply the color components. R+ on the shader sources, didn't check the generated part.

Comment on attachment 548626 [details] [diff] [review] Fix premultiplying to only premultiply the color components. I don't think we want to take changes that only impact our chrome when we don't even use this in our default chrome.

This doesn't only affect chrome; all canvases are transparent on the web, and radial gradients are currently wrong whenever the author uses transparency.

Comment on attachment 548626 [details] [diff] [review] Fix premultiplying to only premultiply the color components. Renomming based on comment 8.

Fwiw, this is incredibly safe and as Joe points out, this does affect all canvases.

Comment on attachment 548626 [details] [diff] [review] Fix premultiplying to only premultiply the color components. Approved for releases/mozilla-aurora

reftest http://hg.mozilla.org/mozilla-central/rev/bae3e43a5173

I was thinking an interesting (and simpler) reftest here might also be to compare on a white background a gradient with stops rgba(0%, 0%, 0%, 100%) rgba(100%, 100%, 100%, 100%) and one with stops rgba(0%, 0%, 0%, 100%) rgba(0%, 0%, 0%, 0%).

Build ID: Mozilla/5.0 (Windows NT 6.1; rv:7.0) Gecko/20100101 Firefox/7.0 Setting this bug as Verified. The issue reported is fixed on Fx7 Beta. Tested following the steps in the description.