[cairo] Finding minimum distance to a stroke or fill

[Bill Spitzak]

It would be nice to return a negative distance if the point is inside 
the path. This is called "level set" representation, and you can 
reproduce suprisingly complex shapes from only a regular grid of such 
values. This is used in 3-D for modelling organic shapes and also for 
fluid simulations.

It looks like your code could be modified to do this easily except it 
will return the distance to internal trapazoid divider lines. However I 
believe this is actually an acceptable result and a legal level-set 
representation of the shape.

You might also want to remove the sqrt() from the return value. The 
caller can do this and some time is saved if they actually don't need 
the root, for instance if they are just comparing to find the nearest one.

Ashwin Bharambe wrote:
> Hi all,
> 
> Attached is a patch which adds two new functions to the cairo API. The
> functions provide functionality for finding the closest point to a
> stroke/fill from a given point (x, y). The function returns the
> distance as well as the co-ordinates of the closest point (px, py).
> Note that returning the distance is redundant and this need not be
> done. The actual signatures of the functions are: