[cairo] Hit detection

[Carl Worth]

On Mon, 27 Nov 2006 13:14:35 +1300, Piotr Zurek wrote:
> That's all good for rectangular (or almost rectangular) objects but what
> about things like bezier curves. Of course, I could calculate that as
> well but I hope there exists an easier way.

For what it's worth, the polygon formed by the control points forms a
nice, easy-to-work-with bounds for the spline, (it's guaranteed to be
contained within the convex hull of the points).

> I guess I should simply ask what's the best way to utilize in_fill and
> in_stroke but maybe someone has different suggestion?

I'd suggest using them as a last resort. Test against bounding
rectangles first, then against more precise bounding polygons, then
use cairo_in_fill and cairo_in_stroke if necessary.

Or something like that anyway, (I haven't really done much application
code with cairo yet, but I would guess this is how I would likely
approach the problem).

-Carl
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