.. _animation-animation_blit_qt4:

animation example code: animation_blit_qt4.py
=============================================

[`source code <animation_blit_qt4.py>`_]

::

    # For detailed comments on animation and the techniqes used here, see
    # the wiki entry http://www.scipy.org/Cookbook/Matplotlib/Animations
    
    import os, sys
    import matplotlib
    matplotlib.use('Qt4Agg') # qt4 example
    
    from PyQt4 import QtCore, QtGui
    
    ITERS = 1000
    
    import pylab as p
    import numpy as npy
    import time
    
    class BlitQT(QtCore.QObject):
        def __init__(self):
            self.ax = p.subplot(111)
            self.canvas = self.ax.figure.canvas
    
            # By making this a child of the canvas we make sure that it is
            # destroyed first and avoids a possible exception when the user clicks
            # on the window's close box.
            QtCore.QObject.__init__(self, self.canvas)
    
            self.cnt = 0
    
            # create the initial line
            self.x = npy.arange(0,2*npy.pi,0.01)
            self.line, = p.plot(self.x, npy.sin(self.x), animated=True, lw=2)
    
            self.background = None
            self.old_size = 0, 0
    
        def timerEvent(self, evt):
            # See if the size has changed since last time round.
            current_size = self.ax.bbox.width, self.ax.bbox.height
    
            if self.old_size != current_size:
                self.old_size = current_size
                self.background = self.canvas.copy_from_bbox(self.ax.bbox)
    
            # restore the clean slate background
            self.canvas.restore_region(self.background)
            # update the data
            self.line.set_ydata(npy.sin(self.x+self.cnt/10.0))
            # just draw the animated artist
            self.ax.draw_artist(self.line)
            # just redraw the axes rectangle
            self.canvas.blit(self.ax.bbox)
    
            if self.cnt==ITERS:
                # print the timing info and quit
                print 'FPS:' , ITERS/(time.time()-self.tstart)
                sys.exit()
    
            else:
                self.cnt += 1
    
    p.subplots_adjust(left=0.3, bottom=0.3) # check for flipy bugs
    p.grid() # to ensure proper background restore
    
    app = BlitQT()
    # for profiling
    app.tstart = time.time()
    app.startTimer(0)
    
    p.show()
    

Keywords: python, matplotlib, pylab, example, codex (see :ref:`how-to-search-examples`)