> On Feb 28, 2020, at 13:17, Fred Kiefer <fredkie...@gmx.de> wrote: > > > >> Am 28.02.2020 um 11:37 schrieb Riccardo Mottola <riccardo.mott...@libero.it>: >> Sergii Stoian wrote: >>> >>>> On Feb 27, 2020, at 23:09, Riccardo Mottola <riccardo.mott...@libero.it> >>>> wrote: >>>> >>>> before a release, I would like these issues to find a solution. >>>> >>>> - understand why we don't work properly on my ThinkPad T23 neither with >>>> the Cairo nor with the xlib backend with similar issues >>> Could you please be more specific and describe these issues? >> >> I have an issue I am working on with Fred, I can forward you some mail >> because they contain screenshot and I did not spam the mailing list. >> >> Essentially I discovered that many windows contain "garbage" and what we >> discovered so far >> - certain windows width cause garbage do be displayed, resizing the window >> may cause it do display correctly >> - this garbage is compatible with an wrong offset increasing for each row >> (you see diagonal lines if you have a white window with a border) >> - the issue happens both with cairo and xlib (recent discovery of two days >> ago, before we were concentrating on a cairo issue) >> >> it looks like an issue that somwehre a padding/alignment is lost: e.g. >> width*bytesPerPixel != bytesPerRow, but where? >> >> I have not seen this issue elsewhere. The T23 is itself a pretty standard >> setup: Devuan ascii, GCC runtime, i386. Only the videocard is a little bit >> vintage/odd (S3) but it works with any other program except GNUstep :-P > > You forgot to mention one important detail. This problem only shows up with > 16 bit depth. Most likely this happens as some data structure that holds the > intermediate pixel information rounds the line length to a multiple of 8, 16, > 32 or even 64 and we use one value below that, so we get an offset for each > line which leads to the displayed garbage. The problem is that I am not able > to reproduce the issue and don’t know which intermediate structure needs > adjustment.
It looks strange. Some regions which are roughly filled with XFillRectangle should look plain. But they don’t (Riccardo sent me a screenshots). We need to be sure the video driver works correctly. The next step is to understand what code in GNUstep drives that weird behaviour.
