Blurry display on Retina macOS computers

> On 12 Feb 2020, at 09:23, Tor Lillqvist <tml@iki.fi> wrote:
>
> In a nutshell, you need to build with macOS SDK 10.13, as SDK 10.14 and 10.15 produce blurry 
> results
>
> But that sounds just like a silly workaround. Does anybody have any insight in what the actual 
> thing going on here is?
>
> --tml

That may be true - but it would be an effective bandaid before a proper fix is found (we’re now up 
to 18 dupes and 64 in CC on the bug…)

Thorsten Wagner found the bandaid, and Emmeran Seehuber tried looking into the underlying issue

Taking the liberty to include them on CC here in case they have further input, Emmeran asked for 
more pointers to look into it

Best,
Eivind



From https://bugs.documentfoundation.org/show_bug.cgi?id=122218#c145
I also tried to look into it. (master on MacOS 10.15.2 with SDK 10.15)

AquaSalGraphics::CheckContext(): The backingScaleFactor of the window is correct (2.0 for Retina) 
and so is the size of the CGLayer used as draw buffer for the window (i.e. twice the window width x 
height). That looks all fine.

For me it seems something gets into a broken state in the CGContextRef while painting the document 
content. Because not only the text but also all lines are blurred. 

This is just guessing, but maybe a scale with a factor other than 2 or something like this? It 
would have to be something affected at compile time, i.e. a constant of the SDK headers which 
changed between SDK 10.12 and 10.13. Or a helper function in a SDK library.

The strange thing is, the print preview of Calc looks fine, i.e. not blurry, everything sharp. The 
print preview of Writer on the other side is blurry. I have this effect both with my master build 
and the official 6.3.4.2 build.

So the print preview of Calc does something different than the rest, because it seems the 
CGContextRef is not getting in this bogus blurry state. 

Any idea how to investigate this future? (I'm new to the LibreOffice code base; Pointers are 
welcome)