Re: [ft] Scaled Outline Coordinates at Scanline Intersections

[Werner LEMBERG]

> I am interested in being able to calculate the value, in 26.6
> coordinates, where the scanlines (at a given ppem) intersect each
> point in a given outline.
> 
> For instance, as a crude example just using pixels:  If I'm dealing with
> an outline of the letter "T", at 8x5 px, I'm looking for a result of
> something like:
> 
> line 0 (top): 1.0 and 7.0
> line 1      : 3.0 and 5.0
> line 2      : 3.0 and 5.0
> line 3      : 3.0 and 5.0
> line 4      : 3.0 and 5.0
> 
> Which visually corresponds to:
> 
> |_|1|2|3|4|5|6|_|
> |_|_|_|3|4|_|_|_|
> |_|_|_|3|4|_|_|_|
> |_|_|_|3|4|_|_|_|
> |_|_|_|3|4|_|_|_|
> 
> What is the easiest way to obtain these values, given an outline and a
> ppem?  I've looked in ftgrays.c, where I imagine I could obtain this
> information, however I'm having a hard time comprehending what is
> happening in there.

Have you tried to run, say, ftview with

  FT2_DEBUG=smooth:7 ftview ...

and look at the debugging output?  This gives the covered pixels per
scanline.  Of course, you have to compile FreeType with debugging
enabled; see docs/DEBUG.


    Werner