implement TrueType Hinting / AutoFit about typography HOT 16 OPEN

It's certainly possibly that there's a bug in my interpreter. Other things to check though: are there embedded bitmaps at this strike size? Also remember that GDI has 3x horizontal resolution thanks to ClearType. You can kind of simulate what the interpreter will do by just giving it 3x more horizontal DPI.

I would try verifying against FreeType and DirectWrite. DWrite has modes to render without ClearType and usually more closely matches what's actually in the font data.

For the blurry stems, that's all about positioning on a pixel boundary. Your layout algorithm probably needs to be smarter about subpixel advances.

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contour analysis2, with polytri-cs (https://github.com/PaintLab/poly2tri-cs)
small yellow points => center of each triangle

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• port SharpFont's TrueType Hinting (https://github.com/MikePopoloski/SharpFont)
  I've tested it :), Tahoma, 8 pts

from the picture,
PixelFarm's Typography now supports TrueType Hinting,

from typography.

I think, I need to fix the Hinting!
It not as clear as expect. :(

from typography.

@MikePopoloski ,
Thank you for your attention. :)

I bring TrueType Hinting code from your repo.
(now locate in https://github.com/LayoutFarm/Typography/blob/master/NetCore/PixelFarm.OpenType/TrueTypeInterperter/Interpreter.cs).

I don't change the inner logic.

I found the the hinted result look blur and
not as clear as expect. (see above).

Do you have any suggestions about how to fix that?

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It works correctly in my repo right? I see that you've changed the code, so I can only assume you've introduced a bug or aren't handling some part of the font parsing correctly.

from typography.

closer look :)
compare side-by-side.

1. SharpFont: Hinted-> use bitmap texture. (fix pixel position)
2. PixelFarm's Typography: Hint -> render each glyph vertex buffer directly to canvas (vary in glyph pixel position)
3. MS Notepad : reference

Tahoma, 11 pts.

each hinted glyphs are very similar.
diff in glyph spacing-> I will fix it later.

I think both of them have the same hint problem.
eg. 'k' glyph -> left upper 'arm' is not sharp
I will investigate further.

goals: to improve glyph quality in both libs

from http://www.antigrain.com/research/font_rasterization/

(Maxim Shemanarev's Agg)

...

This is how the patented aggressive hinting works for the nominal size of 13 pixels. This is why the strokes in “k” look so fragile, almost invisible.

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from typography.

Thank you so much :)

from typography.

• implement http://www.antigrain.com/research/font_rasterization/

(Maxim Shemanarev's Agg)

in short...

So, in short words, for the nice looking text with accurate horizontal positioning we need the following.

1. Use horizontal RGB sub-pixel anti-aliasing for LCD flat panels.
2. Use vertical hinting only and completely discard the horizontal one.
3. Use accurate glyph advance values, calculated at a high resolution for unhinted glyphs.
4. Use accurate, high resolution values from the kerning table.

...

To keep vertical hinting but discard horizontal we simply cheat the hinter. We stretch the symbols horizontally so that, the hinter would have to work with high accuracy in the X direction

...

So, I want to ask David Turner, maybe it makes sense to add an option to his auto-hinter that would modify the Y-direction only, completely discarding the X coordinates. It even can be a special, 1-D hinter that is supposed to be much simpler than the existing one.

related resource : http://jcgt.org/published/0002/01/04/paper.pdf

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Attempt to do AutoFit,
(without original TrueType instruction).

before do grid fitting

glyph 'x' triangulation:

connected centroid1

connected centroid 2

connected centroid 3

connected centroid 4

glyph 'm' edges analysis by triangulation
we can separate inside, outside edges

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Maxim's Agg Vertical Hinting

pic 1:

pic2:

pic3:

(font: Tahoma, 8pts)

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For glyph outline tessellation, you may want to try https://github.com/speps/LibTessDotNet. It works well on .NET core.

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Glyph 'a' :
autofit + vertical hinting + agg's subpixel rendering

Need some color adjustment :)

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Preview Latest AutoFit + SubPixelRendering

pic 1: Tahoma, 8 pt, (1) No AutoFit , (2) with AutoFit,
Tahoma, 10pt, (3) No AutoFit, (4) with AutoFit

from 1, you can see horizontal stem of 'e' in (4) is sharper than (3)

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Preview, Gdi+ vs the Typography

Windows Gdi+ image (SubPixel Rendering, LCD technique) and its zoom pic.
vs PixelFarm's Typography Glyph Rendering, with Vertical AutoFit + Horizontal Fit alignment.
Tahoma 8 pts.

pic 1: upper(1) Gdi+ vs (2) Typography subpixel (lcd) rendering vs (3) Typography gray-scale

Visit the old problem (above), r-r-r sequence

pic 2: Dec 2016, Tahoma 11 pts

pic 3: May 2017, Tahoma 11 pts

pic 4: May 2017, Tahoma 8 pts

TrueType Instruction vs Typography's AutoFit

pic 5: TrueType Instruction Hinted Glyph (Dec 2016), Tahoma 11 pts

pic 6: Typography's AutoFit, with some inter-glyph err at q-u, f-o, and text is too bold

pic 7: Typography's AutoFit + Lcd SubPixelRendering, Tahoma 8pts with some inter-glyph err at w-n

Tahoma 8 pts,

pic 8: vertical-autofit, and horizontal fit alignment

pic 9: vertical-autofit, NO horizontal fit alignment

pic 10: vertical-autofit, and horizontal fit alignment

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