374262 - Translucency support broken in cairogfx builds

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

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Attachment: Test case (use with -chrome)

Although the attachment's <window> has no background, thus triggering translucency, its contents are completely opaque and should obscure everything. This works correctly in a 1.9a2 windows gfx build, but with cairogfx the alpha appears to be completely transparent (which can lead to some surprising effects as the RGB values are expected to be premultiplied but are not) unless you only draw a translucent PNG image in which case the alpha is calculated correctly.

Comment 1

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Attachment: fix

This should fix it; the problem is that we create a 32bpp DIB manually, and then hand the DC to gfxWindowsSurface; the cairo win32 surface needs to create all 32-bit DIBs itself so that it can keep track of various bits needed to make the alpha work.  So, we just create a gfxWindowsSurface and grab its DC.

nsWindow.cpp for win32 really needs to be cleaned up a bit, but that should be done separately from this.

Comment 2

[Stuart Parmenter]

Comment on attachment 259603 [details] [diff] [review]
fix

please file a followup bug on cleaning up that code/removing the cairo ifdefs?

Comment 3

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Checked in; there's a bug already on file on the win32 nsWindow cleanup, need to dig it up.