https://bugs.documentfoundation.org/show_bug.cgi?id=145988

--- Comment #56 from Patrick Luby <[email protected]> ---
(In reply to Patrick Luby from comment #55)
> So, my current theory is that erasing the background of an offscreen image
> is where the problem might be. My logic is that LibreOffice colors set alpha
> values to 1 - Skia's alpha value. What this means is that LibreOffice white
> color in  ARGB format is #00ffffff. Copy this bit for bit directly to a Skia
> white color in BGRA format results in yellow.

I found that, in the Start Center's document thumbnails, the thumbnails are
bitmap images created from the .png images created when you last saved the
document. Also, I found that there is no clearing before drawing the thumbnail
bitmap. Instead, the thumbnail image contains all of the white (yellow with the
bug) pixels that are drawn. So, I think that the color shift is limited to
bitmap images.

Since this bug only affects Skia/Metal and not Skia/Raster, I think that the
next area to look at is if the GPU is returning bitmaps with an unexpected
pixel format. I have posted the following patch that prints messages with pixel
format data for bitmaps fetched from the GPU:

https://gerrit.libreoffice.org/c/core/+/144814/3

If anyone who is experiencing this bug and has a LibreOffice build is willing
to run the above patch, can you apply the patch, make, and then do the
following steps and post all of the "vcl.skia.peekpixels" messages that appear
in the Terminal?:

./instdir/LibreOfficeDev.app/Contents/MacOS/soffice 2>&1 | grep
vcl.skia.peekpixels

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