[Libreoffice-bugs] [Bug 138122] LibreOffice text blurry on Retina displays on macOS 11

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=138122

--- Comment #85 from Jan-Marek Glogowski <glogow at fbihome.de> ---
After reading comment 82, I was curious and downloaded the NeoOffice source,
which - according to their marketing and comment 83 - works correct w.r.t.
"crisp fonts" on MacOS 11 / Big Sur.

An "grep -ri" over the whole NeoOffice codebase for either CALayer or
wantsLayer returns no hits, which IMHO strongly suggests, that the whole
CALayer problem fixed by Qt mentioned in comment 82 is not the same problem LO
has. If you read the original QT bug reference in the commit
(https://bugreports.qt.io/browse/QTBUG-87014), you'll find that Qt has
application startup problems and nothing in the bug's comments indicate
anything else.

So I really doubt LO needs any adoption regarding CALayer handling.

Now for a different idea about the origin of the bug: my assumption is, that
all this is "just" some scaling problem originating in the way Retina screens
are handled in MacOS graphics layer. And IMHO a very strong indicator for a
problem is commit 7c35d5f0669f461254668c1854291e1324b37c21. I introduced that
assert and never saw it failing; but then I never had any Retina HW. And
problems might have originally started with macOS 10.14, when commit
e659c6a1857fbb8e5a6e8ff60fe241483eea32dd as a workaround, which converted the
bitmap context for headless LO into a generic fallback. AFAIK this was
introduced for https://bz.apache.org/ooo/show_bug.cgi?id=91990

And maybe my commit b14371703236160bf34480ef831e9b2244e140ee back then just
made things worse.

My suggestion would be to revert commit
7c35d5f0669f461254668c1854291e1324b37c21 to see, if LO still triggers that
assert and try to find out, why commit e659c6a1857fbb8e5a6e8ff60fe241483eea32dd
is needed at all.

BTW: there is CGContextGetUserSpaceToDeviceSpaceTransform or
CGContextConvertSizeToDeviceSpace, which could indicate some wrong mapping
resulting in scaled text.

P.S. I don't have any mac HW, so I can't test myself.

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