[Webkit-unassigned] [Bug 63075] REGRESSION (r88978): Text inside form controls looks really awful on Windows XP

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=63075





--- Comment #6 from Adam Roben (:aroben) <aroben at apple.com>  2011-06-22 07:09:38 PST ---
I'm stepping through the code using the attached testcase.

Before RenderThemeWin::paintTextField is called, the bitmap is filled with 0xffffffff. RenderThemeWin::paintTextField then fills the text field with 0x00ffffff. Note that the alpha channel has been changed to 0.

Soon later, Font::drawGlyphs is called. At this point the first few pixels are:

0x08000808 0xff728080 0xff808080 0xff808080

The first pixel here is nearly-transparent nearly-black. The second pixel is opaque gray with the red channel darkened a little. The third and fourth pixels are opaque gray.

Over on the UI process side, ::BitBlt does preserve the alpha channel, so these same pixels end up written into the page's BackingStore bitmap. But when the page is displayed on screen, the alpha channel will be ignored, so the nearly-transparent nearly-black pixel will just become a nearly-black pixel, causing the ugly appearance.

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