[cairo] API request: obtain the trapezoids that are outside of the surface

Keith Packard keithp at keithp.com
Fri Aug 20 19:00:13 PDT 2004


Around 17 o'clock on Aug 18, Jost Boekemeier wrote:

> Probably.  Do you know an efficient way to calculate the bounding box of
> a spline? 

For a filled spline, that's trivial, it's just the bounding box of the control 
points.  A bounding box for a stroked spline requires some knowledge of 
the stroke algorithm, but should be essentially the bounding box of the 
control points extended by half of the line width, except when using miter
joints, in which case the miter limit comes into effect.

Converting the stroked path to a filled path and computing the bounding box
of that would generate a more accurate result, at some additional
computational cost.

-keith


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