RE: [Devel] outlines

[Graham Asher]

<<<<<<
I have done a lot of reading as I am new to all of this, but I have yet to
find any real comprehensive information about
outlines. For example, each point in an outline has an associated tag, and
that tag has some meaning for the point. Are the
conic/cubic tag on/off the only important values for a tag?  And if this is
so, why are there more than 3 possible values for
tags as I have seen when reading font info from a font file? Also, if
somebody could point me in the direction of some good
information on how to construct outlines based on point info, I would
greatly appreciate it. So far it eludes me as to how to know
to jump to a point without drawing a line to it, for example.
>>>>>>

An outline is made of a series of contours. Each contour is a closed curve
made from straight line segments and Bezier splines. Points are tagged as
either on-curve, conic (quadratic) control point or cubic control point. A
straight line is drawn between two on-curve points. A conic Bezier spline is
defined by two on-curve points with a single conic control point between
them. A cubic Bezier spline is defined by two on-curve points with two cubic
control points between them.

There is a special case: if two conic control points are next to each other
an on-curve point is assumed to exist half way between them, and is
automatically inserted as the outline is rasterized.

There is no special treatment for illegal sequences of cubic control points.
There have to be exactly two of these between the on-curve points.

Hope this helps.

Graham Asher