A couple thoughts:
1) if you want this to be more precise, you can adjust the scale to
integers, rather than using exactly what ZoomToBB gives you:
in __init__
wx.CallAfter(self.Scale)
this method does the work.
def Scale(self):
self.canvas.ZoomToBB() # to get it close
self.canvas.Scale = round(self.canvas.Scale)
self.canvas.ViewPortCenter = np.round(self.canvas.ViewPortCenter)
self.canvas.SetToNewScale()
Kind of a klunky API -- I should probably add a cleaner way to do that.
I think I get "perfect" results when that's all set that way.
With such a scale (nearly 103%), I was expecting having values from 0 to
> something like 308 or 307 or 306. But here 299.60 seems a bit far away,
> don't you think so ?
>
well:
In [48]: 308 / 1.03
Out[48]: 299.02912621359224
but there is antoher player here:
FloatCanvas keeps track of how the Canvas is zoomed an panned with a Scale
and the ViewPortCenter. -- so the center point was not integers, either, so
two sources of fudging.
So: if you really want exact coords, you can do that above to get them.
But the other option is simply to round the results, and accept that there
may be a off-by-one error sometimes.
If this is the only zoom level you need, then setting it like the above
might make sense. And if you want to suggest a cleaner API for that, I
could add it.
I don't think supporting "use integer scaling" as a general purpose feature
makes sense -- the whole idea of FloatCanvas is that coordinates are
floating point -- any arbitrary scale may make sense for a
given application -- there isn't really anything that special about
integers.
Do you think there is something wrong in the way I compute x and y ? :
>
> def OnMotion(self, event):
> x, y = event.HitCoords[0] - event.BoundingBox[0,0],
> event.BoundingBox[1,1] - event.HitCoords[1]
> print self.canvas.Scale, x, y
>
That's correct, but perhaps unnecessary:
you've placed the image on the canvas at (0,0), so that should be the
corner. You don't need to get it from the bounding box. It's
also available from:
img.XY (and maybe img.Width and img.Height, if you need those)
HTH,
-Chris
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R (206) 526-6959 voice
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