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List:       freetype
Subject:    Re: Hollow fonts and character spacing questions
From:       Werner Lemberg <sx0005 () sx2 ! hrz ! uni-dortmund ! de>
Date:       1998-05-21 13:25:40
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On Wed, 20 May 1998, Pavel Kankovsky wrote:

> > Can FreeType "out of the box", do hollow fonts (i.e., fonts that aren't
> > filled-in)?  I saw in the GLTT library a system that produces a polygon
> 
> Nope. The rasterizer itself can't do that. As a workaround, you can
> extract the outline and draw it yourself or post-process the rendered
> bitmap.

A simple way is to use the following method: if a pixel is painted once,
write a 1 into the bitmap, if it is painted twice, write a 2 etc.

Now draw the pixmap five times:

    the first time as usual,
    the other four times with 1 pixel offset (up/down/left/right)

After doing this, remove all pixels with a count > 1, and you're done.

Of course, this only works well for larger resolutions; additionally it's
really slow -- on the other hand, it's rather simple.


    Werner

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