[HarfBuzz] pango and harfbuzz
behdad at behdad.org
Wed Jun 12 11:00:40 PDT 2013
On 13-06-12 12:19 PM, Felipe Heidrich wrote:
> Thank you Behdad, that is important information to me.
> It seems I will need a mix of pango+harfbuzz.
> pango to itemzime+font-fallback and harfbuzz for shaping (with font features
> support, linear layout).
This should work.
> Do you happen to know what the browsers (firefox, webkit) are doing ?
They do their own itemization / font-fallback, and use harfbuzz or the system
libraries to do shaping.
> Back to rendering, as far as glyph rasterization goes, is there anything I can
> do with cairo/pangocairo that I can't do directly with freetype ?
> Basically I need 8bpp grayscale and 24bpp LCD masks (which I'll upload to an
> opengl texture).
Not really. Lots of bookkeeping and caching...
> Ideally I need to produce subpixel text positioned glyphs (at 0, .33, .66).
Then doing it yourself is easiest indeed.
> On Tue, Jun 11, 2013 at 5:41 PM, Behdad Esfahbod <behdad at behdad.org
> <mailto:behdad at behdad.org>> wrote:
> On 13-06-10 06:04 PM, Felipe Heidrich wrote:
> > Hello,
> > I'm evaluating pango and harfbuzz to use with javafx and I have a couple
> > questions:
> > 1) Advance typographic features (i.e
> > http://dev.w3.org/csswg/css-fonts/#font-rend-props)
> > In pango I was only able to find support for small caps (in PangoVariant)
> Correct. Pango doesn't currently have API to enable those. Though, it's
> straightforward to add.
> > In harfbuzz, hb_shape() takes an array of hb_features_t. I suppose any
> > available in the font can be selected using harfbuzz ?
> > 2) glyph advances
> > Is there any difference between glyph advances produced harfbuzz and pango ?
> > I would like, if possible, to use linear (non-hinted) advances.
> No. With HarfBuzz you have more control over things, but if you disable
> hinting and request a font at a large size you are good to go.
> > Note that I started with pango since it provides a complete solution
> > -itemizer (not mandatory for me)
> > -shaper
> > -font fallback (I think)
> > -glyph metrics (xMax, yMax, xMin, yMin)
> > -glyph images
> > -glyph outlines
> > Turns out that for most of what I'm doing I also need either cairo or
> > to work with pango.
> > I'm not 100% on this one, but using cairo does not provide anything
> extra (as
> > it seems cairo uses freetype).
> > So instead of using pango+cairo or (pango+freetype) I could directly use
> > freetype (for glyph images/outlines/metrics) and harfbuzz (for shaping
> > text).
> You can. But you have to deal with itemizing, bidi, font fallback, etc,
> > Please advise.
> > Thank you
> > Felipe
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