[Matplotlib-users] Bug? in zoom with TkAgg backend

[Xavier G. <gn...@ob...>]

Hi,

TkAgg backend works fine except a corner case with the zoom button.

Consider with simple code :

from pylab import *
A = rand(1000,1000)
imshow(A,interpolation=Nearest)

When I zoom 3 or 4 times on the resulting image using the backend zoom 
button, I get an all white image from a certain zoom level (i.e. from 
factor of 100).

It is clearly a corner case but I sometime have to zoom on very fine 
details.

Consider this code in backend_bases.py :

 lastx, lasty, a, ind, lim, trans = self._xypress
        # ignore singular clicks - 5 pixels is a threshold
        if abs(x-lastx)<5 or abs(y-lasty)<5:
            self._xypress = None
            self.release(event)
            self.draw()
            return

I think we could decrease the threshold down to 1 pixel. Please tell me 
if it is incompatible with another piece of code.

Selecting a less than 1*1 (or 2*2) pixels area should do nothing (and 
not produce a blank image).

Cheers,
Xavier.