[Poppler-bugs] [Bug 25240] Cairo backend for Qt4 wrapper

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=25240

Matthias Berndt <matthias_berndt at gmx.de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|INVALID                     |---
             Status|RESOLVED                    |REOPENED

--- Comment #42 from Matthias Berndt <matthias_berndt at gmx.de> ---
Hi Albert, Hi Cris, Hi Paul,

Cris, there is no point in calling people names, that will not convince
anybody. Albert, I call upon you to not let name-calling as practiced by Nikos
and/or Cris to affect your judgement one way or the other.

I understand that the problem here isn't just the mixing of Qt and Cairo, it's
that you, Albert, disagree that the Cairo backend provides better font
rendering than the Splash backend. Paul provided some screenshots for
comparison on his Github:
https://github.com/giddie/poppler-qt4-cairo-backend

Or more specifically:

https://camo.githubusercontent.com/7b7666f5e7430e950dff8f943a02cd51fbf9e3ac/687474703a2f2f636c6f75642e6769746875622e636f6d2f646f776e6c6f6164732f6769646469652f706f70706c65722d7174342d636169726f2d6261636b656e642f6265666f72652e706e67

vs.

https://camo.githubusercontent.com/d17e13b23523bb29832fe6fe43ea03d182db1d10/687474703a2f2f636c6f75642e6769746875622e636f6d2f646f776e6c6f6164732f6769646469652f706f70706c65722d7174342d636169726f2d6261636b656e642f61667465722e706e67

Albert, please look at these and compare them (you might want to open them in
separate browser tabs so you can easily switch back and forth between them).
I'd like to point out some specific details here:

– compare the 'm' in the word "them" (4th line, last word). In the Cairo
rendering, both arches of the m are equally wide. In the Splash rendering, the
right arch is wider, leading to an asymmetric appearance.
– in the word "library" (4th row, 1st word), the letters 'r' and 'y' should end
at the same height on the top. This is the case in the Cairo rendering but not
in the Splash rendering; the top edge of the 'r' is higher than the top edge of
the 'y'.
– Also in the word library, Splash rendering, the strokes that compose the
letter 'r' look thicker than those of the letter 'y'. In the Cairo rendering,
the strokes have the same thickness.
– zoom in and you'll see that some of the pixels in the Cairo rendering are
coloured, aka subpixel rendering. People generally agree that this leads to a
better visual impression on LCD displays, especially those with limited
resolution.

Based on these things, can we agree on these?
1.) The renderings are different
2.) The Cairo one generally looks better

If we can, then I would like to know why you nevertheless oppose merging these
patches. Specifically, why do you believe that loading Cairo is a problem?
Please keep in mind that
– Cairo is probably already installed anyway (most people have some GTK program
installed)
– The library is 1.2 MB, in a day and age where hardly any computer has less
than 1 GB of memory (my phone has 1 GB and it was a low-cost device when I
bought it two years ago)
– the feature can be disabled when running in resource-constrained
environments.

Trading a little bit of RAM for improved font rendering seems like a reasonable
trade-off to me, but I would like to hear your side of the story.

Best regards,
Matthias

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