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Re: [patch] GAL pixel alignment


On 11/02/2019 22:26, Jeff Young wrote:
> Holes seem different (although perhaps it just a different scrolling
> offset), but not fixed:
Hi Jeff (and others ;-),

I'm working on circle alignment for OpenGL, it also requires some shader
work so it's not that trivial. I'll try to merge all this by Wednesday.

Answering other questions:
- poor cairo graphics on OSX: do you have a Retina display? If so,
what's the native resolution of the screen in your computer and what's
the one reported when creating the cairo context (can you printf
screenSize in CAIRO_GAL::initSurface())? I'm asking because on many OSX
flavors the contents of the window are not rendered at native display
resolution but half of it and then scaled 2 times if the app is not
using Apple's Quartz drawing API? If screenSize <= 2x your native screen
resolution, it's likely the problem causing ugly display. IIRC we had a
similar issue with OpenGL canvas that someone fixed with a special patch
to Mac version of wxWidgets (using some fancy Objective C call).

- concerning text rendering: as JP mentioned already, it's a problem
with our stroke font. It looks bad at low zooms because it lacks
hinting. I doubt it's possible to add it to our stroke font renderer
given the amount of time and effort it requires. Alternative solution is
to use TrueType system fonts, but this surely won't happen earlier than
in V6.

- misaligned arcs and circles are caused by lack of rounding of circle
coordinates/radii in the vertex shader. I'm working on a fix.


>> On 11 Feb 2019, at 21:02, Seth Hillbrand <seth@xxxxxxxxxxxxx
>> <mailto:seth@xxxxxxxxxxxxx>> wrote:
>> Am 2019-02-11 15:37, schrieb Jeff Young:
>>> Will do.
>>> BTW, I just finished building your previous patch.  Sadly it does not
>>> solve the “holes in graphics” anomalies.
>>> Cheers,
>>> Jeff.
>> Hi Jeff-
>> I can't see the holes in graphics issue, but can you check the
>> attached patch if you have time?
>> BTW, if it's just a easy for you, attaching PNGs for the example
>> images will really help.  The TIFF files are not handled by Chrome so
>> I need to save them for Preview.
>> -Seth<0001-GAL-expand-half-pixels-in-super-sampling.patch>
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