Christophe,

Unfortunately, the background is always shifted by integer pixel. So,
shift in data and shift in pixel have some offset and what you see is
the accumulation of this offset.
And you have to manage the pixel and and data coordinates in sync.

For example, you may try to keep the original transform and calculate
the pixel shift in this
coordinate. This would work if you're not worried about the overflow.

The attached example solve this with different approach. However,
dx_data in this approach is not constant but fluctuate, although its
mean value should be one minute.

Regards,

-JJ



On Wed, Aug 5, 2009 at 7:48 AM, Christophe
Dupre<christophe.du...@vhayu.com> wrote:
> Hi JJ,
>
> Thanks for that. It works fairly well, but I've noticed that the graph 
> content (the candlesticks) move slightly faster than the x axis. I've added a 
> sleep(0.1) statement to slow things down, and we can see that at the start 
> the first bar is displayed at around 13:15 but by the times is gets to the 
> left, the same bar is then displayed at about 13:00.
>
> Do you have any suggestion on how to improve that?
>
> Apart from that, shifting the graph is quite fast. On my machine, I get a 
> frame rate of 30 FPS if I redraw both X and Y axis. The rate goes much higher 
> ( greater than 100 FPS) if I don't redraw the axis.
>
> Thanks,
>
> Christophe
>
>
> -----Original Message-----
> From: Jae-Joon Lee [mailto:lee.j.j...@gmail.com]
> Sent: 05 August 2009 03:36
> To: Christophe Dupre
> Cc: matplotlib-users
> Subject: Re: [Matplotlib-users] 0.99.0-RC1 and the animation_blit_gtk2 example
>
> On Tue, Aug 4, 2009 at 12:14 PM, Christophe
> Dupre<christophe.du...@vhayu.com> wrote:
>> Hello,
>>
>>
>>
>> I've been playing with the animation_blit_gtk2 example
>> (http://matplotlib.sourceforge.net/examples/animation/animation_blit_gtk2.html
>>
>> ) and the latest version of matplotlib version 0.99.0-RC1.
>>
>> I've modified the example so that it displays candlesticks moving towards
>> the lelf. The example is attached if anybody is interested.
>>
>>
>>
>>
>>
>> In my example, I'm using 1 minute bars and therefore I would like to shift
>> the graph by 1 minute instead of a few pixels. Is there a way to convert a
>> time difference into pixels?
>>
>
> The "get_dx_data" method coverts a pixel offset to a data offset.
> So, what you need is just to invert it.
> This requires some knowledge of transformation, but I guess the code
> is rather self-explanatory.
>
> For example,  something like below will work (sorry, I haven't
> actually tested the code)
>
>    def get_dx_pixel(self, dx_data):
>        tp = self.ax.transData.transform_point
>        x0, y0 = tp((0, 0))
>        x1, y1 = tp((dx_data, 0))
>        return (x1-x0)
>
> Regards,
>
> -JJ
>
>>
>>
>> Thanks,
>>
>>
>>
>> Christophe
>>
>>
>>
>>
>>
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Attachment: animation_blit_gtk2-3.py
Description: application/python

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