On 06/11/2010 09:09 AM, Michael Droettboom wrote:
> On 06/11/2010 02:38 PM, jason-s...@creativetrax.com wrote:
>> On 6/11/10 1:02 PM, Michael Droettboom wrote:
>>
>>>
>>>> It appears that the difficulty is that quantization is exposed at the
>>>> python level only for collections, via iter_segments.
>>>>
>>>>
>>>>
>>> Sort of. Lines (but none of the other artists) follow what is set by
>>> "set_snap" (the use of two terms for the same thing is also a problem,
>>> of course). This needs to be extended to other artists (and other
>>> relevant backend methods other than draw_path, if necessary). But I
>>> think for convenience, it should also be a global rcParam.
>>>
>> I think a work-around, then (at least it seems to work for me), is
>> setting both snap to False and antialiased to False for the spines.
>> That won't solve the issue for other horizontal lines, but at least it
>> takes care of having the correct origin for the intersection of the
>> spines. (Correct me if I'm wrong, of course!)
>>
>> from matplotlib import pyplot as plt
>> import numpy as np
>> fig = plt.figure()
>> ax = fig.add_subplot(1,1,1, aspect='equal')
>> line1=ax.plot([-1,1],[0,0], color='blue')
>> line2=ax.plot([-1,1],[-1,1], color='red',zorder=5)
>> ax.set_xlim(-1.1,1.1)
>> ax.set_ylim(-1.1,1.1)
>> ax.spines['left'].set_position('zero')
>> ax.spines['left'].set_snap(False)
>> ax.spines['left'].set_antialiased(False)
>> ax.spines['right'].set_color('none')
>> ax.spines['bottom'].set_position('zero')
>> ax.spines['bottom'].set_snap(False)
>> ax.spines['bottom'].set_antialiased(False)
>> ax.spines['top'].set_color('none')
>> ax.xaxis.set_ticks_position('bottom')
>> ax.yaxis.set_ticks_position('left')
>> fig.savefig('test.png',dpi=100)
>>
> I've committed a patch that provides a global snap setting in r8415.
> Set the rcParam "path.snap" to False to turn off all snapping (though it
> should be equivalent to your "set_snap" calls above -- just possibly
> more convenient).
>
> However, I think turning anti-aliasing off will give you the same
> problem at some scales, as anti-aliasing has basically the same effect
> as snapping: rounding to integral pixel values. Try an odd dpi such as
> "67" for example.
I think you meant to say that aliasing is snapping, so with
anti-aliasing off, aliasing is universal, and all points are snapped to
pixels.
Eric
>
> Mike
>
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