Re: The current state of rendering and overlap

2023-12-20 Thread Behdad Esfahbod
On Tue, Dec 19, 2023 at 1:02 PM Skef Iterum wrote: > CFF2 is released, has been for years. As far as I know there's no solid > convention for ignoring unrecognized operators in a CharString, so this > would be CFF2 minor 1 at best. Which would be years out in terms of > support. > > Practically s

Re: The current state of rendering and overlap

2023-12-19 Thread Alexei Podtelezhnikov
> > I think I agree with this - the spec should not bend on > limitations/quirks/bugs in freetype. It isn't the role of the spec to > recommend fonts to be built in with special "hints", just because one > implementation, in its current state, can't render satisfactorily without > those "hints"

Re: The current state of rendering and overlap

2023-12-19 Thread Alexei Podtelezhnikov
> What you're suggesting, if I understand correctly, is that the existing flags > available in the glyf implementation, and a new flag made available in the > CFF2 implementation, be maintained not on the basis of whether a glyph has > overlap, but by the designer based on whether the FreeType r

Re: The current state of rendering and overlap

2023-12-19 Thread Hin-Tak Leung
I think I agree with this - the spec should not bend on limitations/quirks/bugs in freetype. It isn't the role of the spec to recommend fonts to be built in with special "hints", just because one implementation, in its current state, can't render satisfactorily without those "hints". And, we mu

Re: The current state of rendering and overlap

2023-12-19 Thread Skef Iterum
The better angels of my nature tell me to just leave this as it is, as this is archived and may be referenced in the future ... What you're suggesting, if I understand correctly, is that the existing flags available in the glyf implementation, and a new flag made available in the CFF2 implemen

Re: The current state of rendering and overlap

2023-12-19 Thread Alexei Podtelezhnikov
> The 4-fold speed difference is not an optimization, it is a liability which should be taken explicitly. Some overlaps at single points are not that noticeable. Only long runs along the axes are bad. So I disagree with default oversampling even for variation fonts. Let me explain that not all ove

Re: The current state of rendering and overlap

2023-12-19 Thread Skef Iterum
CFF2 is released, has been for years. As far as I know there's no solid convention for ignoring unrecognized operators in a CharString, so this would be CFF2 minor 1 at best. Which would be years out in terms of support. Practically speaking I don't think this could wind up being a "this glyp

Re: The current state of rendering and overlap

2023-12-19 Thread Skef Iterum
I'm afraid the horse has left the barn as far as that goes. Skef On 12/19/23 04:23, Alexei Podtelezhnikov wrote: I would suggest that CFF2 invent a special charstring to mark overlaps with FT_OUTLINE_OVERLAP only when necessary. Let us know to implement it in FreeType.

Re: The current state of rendering and overlap

2023-12-19 Thread Alexei Podtelezhnikov
> > CFF2 is released, has been for years. As far as I know there's no solid > convention for ignoring unrecognized operators in a CharString, so this would > be CFF2 minor 1 at best. Which would be years out in terms of support. We can do it in days for FreeType, then it is a matter of upgra

Re: The current state of rendering and overlap

2023-12-19 Thread Alexei Podtelezhnikov
Why? The sequence 0x0c 0x40 is reserved and not used for example. > I'm afraid the horse has left the barn as far as that goes. > > Skef > >> On 12/19/23 04:23, Alexei Podtelezhnikov wrote: >> I would suggest that CFF2 invent a special charstring to mark overlaps >> with FT_OUTLINE_OVERLAP

Re: The current state of rendering and overlap

2023-12-19 Thread Alexei Podtelezhnikov
Hi Behdad >> >>> Note that freetype does not use the overlap flags to determine the path >>> fill rule (winding vs even-odd), it always uses winding for TT or CFF2 >>> variable fonts, as the spec mandates; the discussion here is about freetype >>> using the (TT glyf only) overlap flags to ena

Re: The current state of rendering and overlap

2023-12-19 Thread Behdad Esfahbod
On Tue, Dec 19, 2023 at 11:25 AM Alexei Podtelezhnikov wrote: > > Note that freetype does not use the overlap flags to determine the path > fill rule (winding vs even-odd), it always uses winding for TT or CFF2 > variable fonts, as the spec mandates; the discussion here is about freetype > using

Re: The current state of rendering and overlap

2023-12-19 Thread Alexei Podtelezhnikov
> > Note that freetype does not use the overlap flags to determine the path fill > rule (winding vs even-odd), it always uses winding for TT or CFF2 variable > fonts, as the spec mandates; the discussion here is about freetype using the > (TT glyf only) overlap flags to enable what Alexei call

Re: The current state of rendering and overlap

2023-12-19 Thread Cosimo Lupo
Note that freetype does not use the overlap flags to determine the path fill rule (winding vs even-odd), it always uses winding for TT or CFF2 variable fonts, as the spec mandates; the discussion here is about freetype using the (TT glyf only) overlap flags to enable what Alexei calls "4x4 bilevel

Re: The current state of rendering and overlap

2023-12-19 Thread Behdad Esfahbod
CFF was even-odd. CFF2 is non-zero winding. behdad http://behdad.org/ On Tue, Dec 19, 2023 at 9:50 AM Hin-Tak Leung wrote: > This is the same as the winding rule concept (overlap once = wounded > twice) ... I seem to remember one of them is even-odd and the other is > non-zero, and quite funda

Re: The current state of rendering and overlap

2023-12-19 Thread Hin-Tak Leung
This is the same as the winding rule concept (overlap once = wounded twice) ... I seem to remember one of them is even-odd and the other is non-zero, and quite fundamental difference between truetype and cff.  On Tuesday, 19 December 2023 at 13:54:21 GMT, Alexei Podtelezhnikov wrote:

Re: The current state of rendering and overlap

2023-12-19 Thread Alexei Podtelezhnikov
>  >> >> It's easy enough to add FT_OUTLINE_OVERLAP to any glyph loaded from a >> CFF2 font. Whether that makes sense is one thing I'd like advice about. >> There's currently no such code. > > I would suggest that CFF2 invent a special charstring to mark overlaps > with FT_OUTLINE_OVERLAP only

Re: The current state of rendering and overlap

2023-12-19 Thread Alexei Podtelezhnikov
> It's easy enough to add FT_OUTLINE_OVERLAP to any glyph loaded from a > CFF2 font. Whether that makes sense is one thing I'd like advice about. > There's currently no such code. I would suggest that CFF2 invent a special charstring to mark overlaps with FT_OUTLINE_OVERLAP only when necessary. Le

Re: The current state of rendering and overlap

2023-12-19 Thread Alexei Podtelezhnikov
> It seemed like the simplest answer to this was to mark all outlines > extracted from a CFF2 font as FT_OUTLINE_OVERLAP, because there's no > inexpensive method of detecting it. And so I added code to do that and > verified it was heeded in ftsmooth.c -- but the ftgrid output didn't > look any dif

Re: The current state of rendering and overlap

2023-12-19 Thread Skef Iterum
I'm not necessarily looking for a "fix", I just want to verify that the CFF2 side is doing what it can and should be. I did run into the thread Cosimo links to in my research, but of course CFF doesn't have either of the glyf flags or any equivalent. It's easy enough to add FT_OUTLINE_OVERLAP

Re: The current state of rendering and overlap

2023-12-19 Thread Werner LEMBERG
> I'm afraid I don't have an exact overlap-less example handy because > the equivalent static font also hints a bit differently, hiding the > issue. But I'm referring to the fact that the upper serifs cover the > upper parts of the stems but the pixels above the stems are darker, so > the overlap

Re: The current state of rendering and overlap

2023-12-19 Thread Cosimo Lupo
Hey Skef, This thread might be of interest to you https://github.com/fonttools/fonttools/issues/2059 On Tue, Dec 19, 2023 at 10:58 AM Skef Iterum wrote: > I'm afraid I don't have an exact overlap-less example handy because the > equivalent static font also hints a bit differently, hiding the is

Re: The current state of rendering and overlap

2023-12-19 Thread Skef Iterum
I'm afraid I don't have an exact overlap-less example handy because the equivalent static font also hints a bit differently, hiding the issue. But I'm referring to the fact that the upper serifs cover the upper parts of the stems but the pixels above the stems are darker, so the overlapping are

Re: The current state of rendering and overlap

2023-12-19 Thread Werner LEMBERG
> I've been looking into various FreeType issues related to the > combination of CFF2 and hinting. As part of that I ran into the > phenomenon represented in the attached capture of ftgrid. Which, to > summarize, has a rendering artifact caused by overlap. What exactly is the artifact? I don't

The current state of rendering and overlap

2023-12-19 Thread Skef Iterum
Hello - I've been looking into various FreeType issues related to the combination of CFF2 and hinting. As part of that I ran into the phenomenon represented in the attached capture of ftgrid. Which, to summarize, has a rendering artifact caused by overlap. It seemed like the simplest answer