matplotlib-devel Mailing List for matplotlib

On 08/26/2011 06:23 AM, Michiel de Hoon wrote:
> Dear all,
>
> I am currently modifying the MacOSX backend to make its interactive/non-interactive behavior consistent with the other backends in matplotlib.
> When I was testing the backend, I found a new bug that seems to be related to a recent change in backend_bases.py:
>
> https://github.com/matplotlib/matplotlib/commit/4c078ddf68cc0ecc1a5f36009a3e3a8b4921b037#lib/matplotlib/backend_bases.py
>
> After this commit, GraphicsContextBase.set_alpha has no effect if alpha==None; previously it would set alpha to 1.0.
>
> The bug appears here in Text.draw in text.py:
>
> gc = renderer.new_gc()
> gc.set_foreground(self.get_color())
> gc.set_alpha(self.get_alpha())
>
> In this code, self is a Text object, which derives from the Artist class, which initializes its _alpha member to None. So self.get_alpha() returns None, and gc.set_alpha has no effect. The alpha value used then depends on whatever was present in the gc before the call to new_gc, which is backend-dependent; the MacOSX and cairo backends end up with an incorrect alpha value.
>
> I guess the easiest solution is to initialize _alpha in the Artist class to 1.0 instead of to None.
No, I think this will foul up all sorts of thing. I will take a look at 
this today or tomorrow at the latest.
Eric
>
> Thanks,
> --Michiel
>

Dear all,
I am currently modifying the MacOSX backend to make its interactive/non-interactive behavior consistent with the other backends in matplotlib.
When I was testing the backend, I found a new bug that seems to be related to a recent change in backend_bases.py:
https://github.com/matplotlib/matplotlib/commit/4c078ddf68cc0ecc1a5f36009a3e3a8b4921b037#lib/matplotlib/backend_bases.py
After this commit, GraphicsContextBase.set_alpha has no effect if alpha==None; previously it would set alpha to 1.0.
The bug appears here in Text.draw in text.py:
 gc = renderer.new_gc()
 gc.set_foreground(self.get_color())
 gc.set_alpha(self.get_alpha())
In this code, self is a Text object, which derives from the Artist class, which initializes its _alpha member to None. So self.get_alpha() returns None, and gc.set_alpha has no effect. The alpha value used then depends on whatever was present in the gc before the call to new_gc, which is backend-dependent; the MacOSX and cairo backends end up with an incorrect alpha value.
I guess the easiest solution is to initialize _alpha in the Artist class to 1.0 instead of to None.
Thanks,
--Michiel

Just brain-storming here... What about two rcparams: cycle.color = true and
cycle.style = false?
This way, cycling for both colors and line styles could be turned on and off
accordingly. Then, a b&w mode could utilize this. as well as possibly
substitute default values.
Ben Root
On Thursday, August 25, 2011, Eric Firing <ef...@ha...> wrote:
> On 08/25/2011 04:09 AM, Benjamin Root wrote:
>> I am currently in the process of a paper submission, and the page charge
>> estimation took us for a bit of a surprise. Luckily, most of my plots
>> don't need color, and I would like to regenerate them in b&w mode.
>>
>> Is there some default line style cycle (I.e., ['-', '.', '--', '.-'])
>> that can be set analogous to the color cycle used by default?
>
> Something like this came up a while ago as a feature request--same sort
> of motivation, I think--but it was never implemented.
>
> You could make a little function that would operate on line objects,
> changing colors from the color cycle to black while using those colors
> to specify line styles.
>
> Eric
>
>>
>> Thanks,
>> Ben Root
>
>
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