On 6/6/2016 8:36 PM, David Christiansen wrote:
> That seems overly complicated. Can you not just compare the mouse's
> coordinates to the picture's location in the canvas?
I don't have a good way to know where the picture itself is - only its
bounding box. So if the picture consists of a doughnut shape, I want
the center of the doughnut and the region around its edge to not count
as clicks on it.
Understood. Is it possible to define a region to represent the
clickable areas? This is the way I would do it if possible.
I haven't done much GUI programming in Racket, so I don't know exactly
what it can do, but in, e.g., Windows GDI you can create a region
directly from a binary (1-bit depth) bitmap [and a bitmap of any depth
can be converted to a binary bitmap]. Set (1) pixels in the bitmap will
be included in the region and unset (0) pixels will be excluded.
A region can directly answer whether a point (mouse coordinate) is
inside it or not.
George
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