pan/zoom axes problem

Hi,

I'm a newbie to matplotlib. I'm embedding matplotlib (0,98.5.3) in a
pyqt application. I'm using the qt4 backend and its navigation
toolbar.

I wish to execute a certain function every time the view interval of
a figure is changed interactively (i.e. using the zoom rectangle or
the
axes pan/zoom button of the navigation toolbar). I'm interested in
changes due to axes zoom and rectangle zoom but not in changes due
axes pan. The only way I know for detecting this changes is
'x/ylim_changed' events. Unfortunately I don't know how to distinguish
if the
event is caused by a rectangle zoom, an axes zoom or an axes pan.
I've read the events section of the documentation and searched the
archives for a solution with no luck. Could somebody help me to
solve this problem?

Thanks in advance.

Vicent

PS:

···

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Hi Vicent,

I think the following example may help you, althogh their might be a better
way:

···

##############################
import matplotlib.pyplot as plt

def callback(ax):
    """ prints mode of toolbar after limits changed

          e.g.
           mode : >zoom rect<
           mode : >pan/zoom<
    """
    print " mode : >%s<" % (plt.get_current_fig_manager().toolbar.mode)

ax = plt.gca()
ax.callbacks.connect('xlim_changed', callback)
ax.callbacks.connect('ylim_changed', callback)
plt.show()
######################################

kind regards Matthias

On Thursday 03 September 2009 14:07:06 Vicent Mas wrote:

Hi,

I'm a newbie to matplotlib. I'm embedding matplotlib (0,98.5.3) in a
pyqt application. I'm using the qt4 backend and its navigation
toolbar.

I wish to execute a certain function every time the view interval of
a figure is changed interactively (i.e. using the zoom rectangle or
the
axes pan/zoom button of the navigation toolbar). I'm interested in
changes due to axes zoom and rectangle zoom but not in changes due
axes pan. The only way I know for detecting this changes is
'x/ylim_changed' events. Unfortunately I don't know how to distinguish
if the
event is caused by a rectangle zoom, an axes zoom or an axes pan.
I've read the events section of the documentation and searched the
archives for a solution with no luck. Could somebody help me to
solve this problem?

Thanks in advance.

Vicent

PS:

Hi Matthias,

2009/9/3 Matthias Michler <MatthiasMichler@...361...>:

Hi Vicent,

I think the following example may help you, althogh their might be a better
way:

thanks for your answer. It really helps. I didn't know about the mode
attribute of navigation toolbars. Inspecting the
NavigationToolbar2QTAgg class interactively with an IPython shell
doesn't show such attribute for this class. Maybe it is created
dynamically when the pan/zoom button is clicked?

Now I still have to find out how to distinguish axes pan from axes
zoom cases. I suppose I can use 'button_press_event' canvas events and
use the button attribute of these events for knowing if the user is
doing a pan or a zoom: pan/zoom mode + left button --> user is panning
axes, pan/zoom mode + right button --> user is zooming axes. Right?

Anyway, thanks again for your help.

···

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Hi Vicent,

Hi Matthias,

2009/9/3 Matthias Michler <MatthiasMichler@...361...>:
> Hi Vicent,
>
> I think the following example may help you, althogh their might be a
> better way:

thanks for your answer. It really helps. I didn't know about the mode
attribute of navigation toolbars. Inspecting the
NavigationToolbar2QTAgg class interactively with an IPython shell
doesn't show such attribute for this class. Maybe it is created
dynamically when the pan/zoom button is clicked?

I think: The attribute 'mode' is added during the initialisation of the
toolbar (actually it is set during the initalisation of
backend_qt.NavigationToolbar2QT and therefore you can see it directly as
attribute of the abstract class NavigationToolbar2QTAgg, which inherits from
backend_qt.NavigationToolbar2QT).

Therefore the following works:
import matplotlib
matplotlib.use("QTAgg")
import matplotlib.pyplot as plt

print "initialised toolbar : ", plt.get_current_fig_manager().toolbar
print " >%s<" % (plt.get_current_fig_manager().toolbar.mode)

Now I still have to find out how to distinguish axes pan from axes
zoom cases. I suppose I can use 'button_press_event' canvas events and
use the button attribute of these events for knowing if the user is
doing a pan or a zoom: pan/zoom mode + left button --> user is panning
axes, pan/zoom mode + right button --> user is zooming axes. Right?

I send you again my previous example with some additional lines. In my opinion
you can use either 'button_press_event' or axes-callbacks to achieve what
you want, but maybe I'm missing something.

regards Matthias

import matplotlib.pyplot as plt

def callback(ax):
    """ prints mode of toolbar after limits changed

          e.g.
           mode : >zoom rect<
           mode : >pan/zoom<
    """
    print " mode : >%s<" % (plt.get_current_fig_manager().toolbar.mode)

    if plt.get_current_fig_manager().toolbar.mode == 'zoom rect':
        print "We are in zoom with Rectangle - mode"
    elif plt.get_current_fig_manager().toolbar.mode == 'pan/zoom':
        print "We are in pan/zoom - mode"

def fct(event):
    """ print zoom-mode after 'button_press_event' """
    if plt.get_current_fig_manager().toolbar.mode == 'zoom rect':
        print "We are in zoom with Rectangle - mode"
    elif plt.get_current_fig_manager().toolbar.mode == 'pan/zoom':
        print "We are in pan/zoom - mode"
    
ax = plt.gca()
##ax.callbacks.connect('xlim_changed', callback)
##ax.callbacks.connect('ylim_changed', callback)

plt.connect("button_press_event", fct)
plt.show()

···

On Thursday 03 September 2009 18:14:37 Vicent Mas wrote:

Hi Matthias ,

thanks a lot for your explanations. They were very useful.

Vicent

···

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Dear Vicent,

I'm struggling with embedding a navigation toolbar in a QT4 application with
matplotlib canvas. Could you please send me an example code of how I add the
navigation toolbar in the first place?

As you notice, I'm a real newbe!

Thank you very much,

Thom

Vicent Mas-2 wrote:

···

Hi Matthias ,

thanks a lot for your explanations. They were very useful.

Vicent

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Sent from the matplotlib - users mailing list archive at Nabble.com.

Dear Vicent,

I'm struggling with embedding a navigation toolbar in a QT4 application
with matplotlib canvas. Could you please send me an example code of how I
add the navigation toolbar in the first place?

As you notice, I'm a real newbe!

Thank you very much,

Thom

Vicent Mas-2 wrote:
> Hi Matthias ,
>
> thanks a lot for your explanations. They were very useful.
>
> Vicent

Hi,

you can start here (it is what I did :-):

http://eli.thegreenplace.net/2009/05/23/more-pyqt-plotting-demos/

Hope it helps.

Vicent
::

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