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Re: Kerning
by christoph on Tuesday 28/Aug/2007, @17:29
Aww, the character positioning looks really bad for all of the fonts in that screenshot.

The problem is that Qt (being based on the OS's native font system) does only support integral character positions, making it impossible to get correct layout (line lengths etc.) and correct positioning at the same time.

Please see <A HREF="http://antigrain.com/research/font_rasterization/index.html">http://antigrain.com/research/font_rasterization/index.html</A> for some awesome results that are possible using FreeType directly, bypassing the OS's font system.

Especially worth noting is <A HREF="http://antigrain.com/research/font_rasterization/sample_arial_03.png">this screenshot</A> (yes the font is small, but this even more so proves the author's point).
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Re: Kerning
by Boudewijn Rempt on Wednesday 29/Aug/2007, @00:53
Given that there's no word processing software yet that works the way the author of that article proposes, it's a bit silly to hold it up as the standard. Compared to the same text in OO.org or Abiword, KOffice 2.0 is doing really well.
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  • Re: Kerning
    by André on Wednesday 29/Aug/2007, @05:15
    Still, you have to admit that the results look pretty amazing. At least to my rather untrained eye.
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Re: Kerning
by Thomas Zander on Wednesday 29/Aug/2007, @10:02
> The problem is that Qt (being based on the OS's native font system) does
> only support integral character positions, making it impossible to get
> correct layout (line lengths etc.) and correct positioning at the same time.

Qt's font system uses qreal (doubles) in the API everywhere and maps that to a high-res grid of integers to keep things fast. There is virtually no loss there so the statement above doesn't really apply to the KWord case. Sorry.
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  • Re: Kerning
    by christoph on Thursday 30/Aug/2007, @10:50
    You are right about the API and internal calculations using qreals, but the actual rendering is not done in sub-pixel positioned precision.

    Try rendering a couple of letters each moved by a fractional pixel coordinate, and you will see that they all end up looking the same.

    Compare that to KPDF's rendering (3.5.7, didn't try 3.91 yet), where the bitmap of a letter is different depending on (sub-pixel) position.

    Of course it also has to do with Qt (or FreeType?) trying very hard to cache the bitmaps. In earlier versions of Qt/FreeType, you could bypass caching by scaling with, say, a factor of 1.00001, and get very good results. But in recent versions, the cache is used even for rotated fonts, making the result look really funny.

    And seeing the good quality of KPDF and its good speed, I doubt that a Word Processor couldn't get nearly the same results.
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Re: Kerning
by Vide on Friday 31/Aug/2007, @04:39
Sorry maybe I'm blind but I see no problems at all with kerning in Boudewijn's screenshot
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