[PATCH] gdiplus: in CompositingModeSourceCopy, fully transparent pixels are drawn black

[Damjan Jovanovic]

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=42585

Signed-off-by: Damjan Jovanovic 
---
 dlls/gdiplus/graphics.c    | 7 ++++++-
 dlls/gdiplus/tests/image.c | 2 +-
 2 files changed, 7 insertions(+), 2 deletions(-)

[Jeff Smith]

On Wed, Mar 4, 2020, 7:36 PM Damjan Jovanovic  wrote:
> Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=42585
> Signed-off-by: Damjan Jovanovic
>
> dlls/gdiplus/graphics.c    | 7 ++++++-
>  dlls/gdiplus/tests/image.c | 2 +-
>  2 files changed, 7 insertions(+), 2 deletions(-)

Hi Damjan,

I've looked at this area of GDI+ recently. Effectively what seems to happen
for copy is the source color is converted PARGB (pre-multiplied) then back
to ARGB.  I hadn't decided if I had considered all code paths though.

However, if this patch does fix the application bug, it still seems like an
improvement.

Thanks,
Jeff

[Vincent Povirk (they/them)]

I'm wondering if this should be in setpixel_32bppARGB. Does
GdipBitmapSetPixel also work this way?

[Jeff Smith]

No, GdipBitmapSetPixel on ARGB sets the exact color value passed in.

GdipGraphicsClear, GdipFill*, and GdipDraw* functions all exhibit the
ARGB -> PARGB -> ARGB behavior IIRC.

On Thu, Mar 5, 2020 at 10:39 AM Vincent Povirk (they/them)
 wrote:
> I'm wondering if this should be in setpixel_32bppARGB. Does
> GdipBitmapSetPixel also work this way?

[Vincent Povirk (they/them)]

Signed-off-by: Vincent Povirk