Re: [Devel] underlining in freetype2

[Leonard Rosenthol]

At 11:03 AM -0400 8/5/02, Stephen C. North wrote:

> We'd like to add this feature to graphviz
> (www.graphviz.org).

        Excellent!

> Do you recommend that we just try to
> figure out how to do this
> by reading ImageMagick or librsvg source,
> or do you have a
> separate patch?  Any
> advice?

        I don't have a specific patch, but it's pretty easy to do.  You just need to read a couple of fields from the font metrics and then use them to position and draw the line.

From the metrics.

  metrics->underline_position=face->underline_position/64.0;
  metrics->underline_thickness=face->underline_thickness/64.0;

And here is the code from ImageMagick to do position and draw:

    clone_info->affine.tx=offset.x;
    clone_info->affine.ty=offset.y;
    FormatString(primitive,"stroke-width %g line 0,0 %g,0",
      metrics.underline_thickness,metrics.width);
    if (annotate->decorate == OverlineDecoration)
      {
        clone_info->affine.ty-=draw_info->affine.sy*
          (metrics.ascent+metrics.descent)-metrics.underline_position;
        (void) CloneString(&clone_info->primitive,primitive);
        (void) DrawImage(image,clone_info);
      }
    else
      if (annotate->decorate == UnderlineDecoration)
        {
          clone_info->affine.ty-=metrics.underline_position;
          (void) CloneString(&clone_info->primitive,primitive);
          (void) DrawImage(image,clone_info);

        }

Leonard

-- 

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Leonard Rosenthol                            <mailto:address@hidden>
                                              <http://www.lazerware.com>