Re: [matplotlib-devel] ginput: blocking call for mouse input

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Ooops, I had forgotten to add the Wx backend. Here is a new patch.

By the way, with the wx backend, there seems to be a simple mistake in
the "show" method of the figure manager, to reproduce the traceback do
(with a recent ipython):

ipython -wthread -pylab
In [1]: f = figure()

In [2]: f.show()

Cheers,

Gaël

On Wed, Jan 30, 2008 at 03:05:13AM +0100, Gael Varoquaux wrote:
> Hi all,

> A while ago (a year or so), I was looking for a ginput-like function with
> matplotlib. For those who don't know what I am talking about, it is a
> blocking call that can be used in a script to ask the user to enter
> coordinnate by clicking on the figure. This is incredibly handy, as it
> allows some simple user interaction without worrying about events loop
> and Co.

> At the time I gave up on that. I have made progress with GUI and event
> loops, and a recent post on the matplotlib-user list put me back to work
> on this (
> http://www.nabble.com/ginput-is-here%21-%28for-wx-anyway%29-to14960506.html
> ).

> I have a preliminary patch to add this feature to matplotlib that I
> attach. I add a method to the backend canvases, to be able to deal with
> event-loop-handling, and following Jack Gurkesaft I create my own a small
> event-loop to poll for events inside my function. This is a kludge, but it
> allows to block the function while still processing events. If you have
> better ideas.

> I have implemented the functionnality for all the interactive backends I
> could test (and thus not cocoa), but I am not too sure my gtk code is
> kosher, I wouldn't mind advice on this one.

> The code of ginput itself is currently in a seperate file
> (matplotlib.ginput, that you can run for a demo) because I wasn't too
> sure where to add it.

> This is a first version of the patch. I would like comments on it,
> especially where to add the code itself, and if the proposed additions to
> the backends look all right.

> Once I have comments, I plan to:

>     * Make right click cancel an input
>     * Allow infinite number of inputs, terminated by right-click
>     * Add optional display of inputs
>     * Rework docstrings

> More suggestions welcomed,

> This could (and should, IMHO) open the road to other blocking calls for
> user interaction, like the selection of a window, as they make life
> really easy for people wanting to hack quick data analysis scripts.

> Cheers,

> Gaël

> Index: trunk/matplotlib/lib/matplotlib/backend_bases.py
> ===================================================================
> --- trunk/matplotlib/lib/matplotlib/backend_bases.py	(revision 4908)
> +++ trunk/matplotlib/lib/matplotlib/backend_bases.py	(working copy)
> @@ -1151,7 +1151,13 @@
>          """
>          return self.callbacks.disconnect(cid)

> +    def flush_events(self):
> +        """ Flush the GUI events for the figure. Implemented only for
> +        backends with GUIs.
> +        """
> +        raise NotImplementedError

> +
>  class FigureManagerBase:
>      """
>      Helper class for matlab mode, wraps everything up into a neat bundle
> Index: trunk/matplotlib/lib/matplotlib/ginput.py
> ===================================================================
> --- trunk/matplotlib/lib/matplotlib/ginput.py	(revision 0)
> +++ trunk/matplotlib/lib/matplotlib/ginput.py	(revision 0)
> @@ -0,0 +1,80 @@
> +
> +from matplotlib.pyplot import gcf
> +import time
> +
> +class BlockingMouseInput(object):
> +    """ Class that creates a callable object to retrieve mouse click 
> +        in a blocking way, a la MatLab. 
> +    """
> +
> +    callback = None 
> +    verbose = False
> +
> +    def on_click(self, event):
> +        """ Event handler that will be passed to the current figure to
> +            retrieve clicks.
> +        """
> +        # if it's a valid click, append the coordinates to the list
> +        if event.inaxes:
> +            self.clicks.append((event.xdata, event.ydata))
> +            if self.verbose: 
> +                print "input %i: %f,%f" % (len(self.clicks), 
> +                                    event.xdata, event.ydata)
> +
> +    def __call__(self, fig, n=1, timeout=30, verbose=False):
> +        """ Blocking call to retrieve n coordinate pairs through mouse 
> +            clicks.
> +        """
> +
> +        assert isinstance(n, int), "Requires an integer argument"
> +
> +        # Ensure that the current figure is shown 
> +        fig.show()
> +        # connect the click events to the on_click function call
> +        self.callback = fig.canvas.mpl_connect('button_press_event', 
> +                                                    self.on_click)
> +
> +        # initialize the list of click coordinates
> +        self.clicks = []
> +
> +        self.verbose = verbose
> +
> +        # wait for n clicks
> +        counter = 0
> +        while len(self.clicks) < n:
> +            fig.canvas.flush_events()
> +            # rest for a moment
> +            time.sleep(0.01)
> +
> +            # check for a timeout
> +            counter += 1
> +            if timeout > 0 and counter > timeout/0.01: 
> +                print "ginput timeout"; 
> +                break;
> +
> +        # All done! Disconnect the event and return what we have
> +        fig.canvas.mpl_disconnect(self.callback)
> +        self.callback = None
> +        return self.clicks
> +
> +
> +def ginput(n=1, timeout=30, verbose=False):
> +    """
> +    Blocking call to interact with the figure. 
> +
> +    This will wait for n clicks from the user and return a list of the 
> +    coordinates of each click.
> +
> +    If timeout is negative, does not timeout.
> +    """
> +
> +    blocking_mouse_input = BlockingMouseInput()
> +    return blocking_mouse_input(gcf(), n, timeout, verbose=verbose)
> +
> +if __name__ == "__main__":
> +    import pylab
> +    t = pylab.arange(10)
> +    pylab.plot(t, pylab.sin(t))
> +    print "Please click"
> +    ginput(3, verbose=True)
> +
> Index: trunk/matplotlib/lib/matplotlib/backends/backend_qt.py
> ===================================================================
> --- trunk/matplotlib/lib/matplotlib/backends/backend_qt.py	(revision 4908)
> +++ trunk/matplotlib/lib/matplotlib/backends/backend_qt.py	(working copy)
> @@ -175,6 +175,9 @@

>          return key

> +    def flush_events(self):
> +        qt.qApp.processEvents()
> +
>  class FigureManagerQT( FigureManagerBase ):
>      """
>      Public attributes
> Index: trunk/matplotlib/lib/matplotlib/backends/backend_gtk.py
> ===================================================================
> --- trunk/matplotlib/lib/matplotlib/backends/backend_gtk.py	(revision 4908)
> +++ trunk/matplotlib/lib/matplotlib/backends/backend_gtk.py	(working copy)
> @@ -386,6 +386,13 @@
>      def get_default_filetype(self):
>          return 'png'

> +    def flush_events(self):
> +        gtk.gdk.threads_enter()        
> +        while gtk.events_pending():
> +            gtk.main_iteration(True)
> +        gtk.gdk.flush()
> +        gtk.gdk.threads_leave()
> +        

>  class FigureManagerGTK(FigureManagerBase):
>      """
> Index: trunk/matplotlib/lib/matplotlib/backends/backend_tkagg.py
> ===================================================================
> --- trunk/matplotlib/lib/matplotlib/backends/backend_tkagg.py	(revision 4908)
> +++ trunk/matplotlib/lib/matplotlib/backends/backend_tkagg.py	(working copy)
> @@ -269,8 +269,9 @@
>          key = self._get_key(event)
>          FigureCanvasBase.key_release_event(self, key, guiEvent=event)

> +    def flush_events(self):
> +        self._master.update()

> -
>  class FigureManagerTkAgg(FigureManagerBase):
>      """
>      Public attributes
> Index: trunk/matplotlib/lib/matplotlib/backends/backend_qt4.py
> ===================================================================
> --- trunk/matplotlib/lib/matplotlib/backends/backend_qt4.py	(revision 4908)
> +++ trunk/matplotlib/lib/matplotlib/backends/backend_qt4.py	(working copy)
> @@ -13,7 +13,7 @@
>  from matplotlib.mathtext import MathTextParser
>  from matplotlib.widgets import SubplotTool

> -from PyQt4 import QtCore, QtGui
> +from PyQt4 import QtCore, QtGui, Qt

>  backend_version = "0.9.1"
>  def fn_name(): return sys._getframe(1).f_code.co_name
> @@ -174,6 +174,9 @@

>          return key

> +    def flush_events(self):
> +        Qt.qApp.processEvents()
> +
>  class FigureManagerQT( FigureManagerBase ):
>      """
>      Public attributes

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-- 
  Gael Varoquaux,
  Quantum degenerate gases group
  European Laboratory for Non-Linear Spectroscopy
    University of Florence, Polo Scientifico
    Via Nello Carrara 1, I-50019-Sesto-Fiorentino (Firenze) Italy
    Phone: ++ 390-55-457242145      Fax: ++ 390-55-4572451
  ++ and ++
  Groupe d'optique atomique,
  Laboratoire Charles Fabry de l'Institut d'Optique
    Campus Polytechnique, RD 128, 91127 Palaiseau cedex FRANCE
    Tel : 33 (0) 1 64 53 33 23 - Fax : 33 (0) 1 64 53 31 01
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