Fix SplashScreen fade-out transparency regression after CsWin32 refactor (#11321)#11485
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sachPundir wants to merge 1 commit intodotnet:mainfrom
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Fix SplashScreen fade-out transparency regression after CsWin32 refactor (#11321)#11485sachPundir wants to merge 1 commit intodotnet:mainfrom
sachPundir wants to merge 1 commit intodotnet:mainfrom
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Initialize _blendFunction instead of using a local BLENDFUNCTION instance. During fade-out, the uninitialized field caused AlphaFormat to be 0, resulting in transparent regions rendering gray. Fixes dotnet#11321
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Fixes #11321
Description
During the migration of
SplashScreento CsWin32 APIs,CreateWindowinitialized a local
BLENDFUNCTIONvariable and passed it toUpdateLayeredWindow, but never assigned it to the_blendFunctionfield.As a result,
_blendFunctionused inFadeout_Tickremaineddefault-initialized with
AlphaFormat = 0. WithoutAC_SRC_ALPHA,UpdateLayeredWindowignores per-pixel alpha entirely, causing transparentregions of the splash image to briefly render as black during fade-out.
The fix assigns directly to
_blendFunctioninCreateWindowso thatFadeout_Tickinherits the correctAlphaFormat = AC_SRC_ALPHA.Customer Impact
Applications using
SplashScreenwith PNG images containing transparencywill see transparent regions turn black during fade-out.
Regression
Yes. Introduced during the CsWin32 refactor of
SplashScreen.Testing
remain transparent throughout.
autoCloseand manualClose(TimeSpan)scenarios.Risk
Low. Single-field initialization change. No logic, API, or behavioral
changes beyond correcting the regression.
Microsoft Reviewers: Open in CodeFlow