I don't know who I should notify about this, but I've found a fix for simple
animation. If one uses the code found here:
http://matplotlib.sourceforge.net/examples/animation/simple_anim_gtk.html it
works okay, but if you try to move the window it freezes, and you can't use
anything on the toolbar. Really annoying, and why not quite a bug, its
definitely undesirable behavior. So I've found a very simple fix that leaves
the gui reasonably interactive and the window is freely movable. It centers
around using a python generator and the yield statement. Calling "yield
some_variable" in a function causes execution to stop at that point until the
generator's next() method is called, this allows us to "pause" the execution of
the animate() function and return control the gui thread. As it currently
stands, once animate() is called it executes until completion, never allowing
gui events to be handled, hence the freezing. The solution is changing too
lines of
code, note that this is for the GTK example but the same principle should be
applicable to the other backends. Note that there are extra explanatory
comments that could be removed when posting the actual example.
-- Nathaniel
"""
A simple example of an animated plot using a gtk backend
"""
import time
import numpy as np
import matplotlib
matplotlib.use('GTKAgg') # do this before importing pylab
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.add_subplot(111)
def animate():
tstart = time.time() # for profiling
x = np.arange(0, 2*np.pi, 0.01) # x-array
line, = ax.plot(x, np.sin(x))
for i in np.arange(1,200):
line.set_ydata(np.sin(x+i/10.0)) # update the data
fig.canvas.draw() # redraw the canvas
# Here is generator magic that stops execution of animate() till the
generators next() method is called
yield True # continue animating
print 'FPS:' , 200/(time.time()-tstart)
raise SystemExit
import gobject
print 'adding idle'
# This is some lambda and python magic:
# Python only evaluates defaults for arguments once,
# so the first call to this lambda function sets iter to the generator made
(automagically) from the animate() function.
# Each subsequent call to the lambda function calls iter.next() which
restarts(unpauses) execution of the animate() function,
# until it yeilds again, at which point control goes back to the gui
# These calls are done when the gui is idle, hence why we are registering an
idle callback,
gobject.idle_add(lambda iter=animate(): iter.next())
print 'showing'
plt.show()------------------------------------------------------------------------------
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