From: Benjamin Root <ben.root@ou...>  20110505 23:27:30

On Tue, May 3, 2011 at 3:57 AM, Gerald Storer <gds@...> wrote: > Hello, > > I've been trying to animate some plots with the qt backend and run into > a couple of problems. > > Firstly, > I'd like to be able to update the axis limits in an automated fashion as > the data changes size. > > Secondly, > Resizing figures appears to redraw everything _but_ items with the > animation flag. The is causing me problems when the animation is paused > or the frames are occurring slow enough such that there is a noticable > period where the my lines disappear. > > I've sort of solved both of these problems but the solutions seem > hackish. In particular updating the axis limits is slowing the > animation by 25% and toggling the animated field using the qt events > just feels like its asking for trouble. > > Below is the qt animation example with my solutions. Adjust the size of > the plot after the animation finishes to see the effect of the resize > hack. I would be grateful if anyone could suggest some improvements. > > Thanks, > Gerald. > > # For detailed comments on animation and the techniqes used here, see > > # the wiki entry http://www.scipy.org/Cookbook/Matplotlib/Animations > > import os > > import sys > > #import matplotlib > > #matplotlib.use('Qt4Agg') > > from matplotlib.figure import Figure > > from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as > FigureCanvas > > from PyQt4 import QtCore, QtGui > > ITERS = 100 > > import numpy as np > > import time > > class BlitQT(FigureCanvas): > > def __init__(self): > > FigureCanvas.__init__(self, Figure()) > > self.ax = self.figure.add_subplot(111) > > #self.ax.grid() > > self.draw() > > self.old_size = self.ax.bbox.width, self.ax.bbox.height > > self.ax_background = self.copy_from_bbox(self.ax.bbox) > > self.cnt = 0 > > self.x = np.arange(0,2*np.pi,0.01) > > self.sin_line, = self.ax.plot(self.x, np.sin(self.x), > animated=True) > > self.cos_line, = self.ax.plot(self.x, np.cos(self.x), > animated=True) > > self.draw() > > self.old_limits = self.ax.get_xlim(),self.ax.get_ylim() > > self.tstart = time.time() > > self.maintimer = self.startTimer(10) > > ## HACK for disapearing objects on resize > > def resizeEvent(self,evt): > > super(BlitQT,self).resizeEvent(evt) > > self.sin_line.set_animated(False) > > def paintEvent(self,evt): > > super(BlitQT,self).paintEvent(evt) > > self.sin_line.set_animated(True) > > def timerEvent(self, evt): > > current_size = self.ax.bbox.width, self.ax.bbox.height > > if self.old_size != current_size: > > self.old_size = current_size > > #self.ax.clear() > > #self.ax.grid() > > self.draw() > > self.ax_background = self.copy_from_bbox(self.ax.bbox) > > self.restore_region(self.ax_background) > > # update the data > > > self.sin_line.set_ydata(np.sin(self.x+self.cnt/10.0)*self.cnt/100.0) > > > self.cos_line.set_ydata(np.cos(self.x+self.cnt/10.0)*self.cnt/100.0) > > ## HACK for updating axis limits > > self.ax.relim() > > self.ax.autoscale_view() > > current_limits = self.ax.get_xlim(),self.ax.get_ylim() > > if self.old_limits != current_limits: > > self.old_limits = current_limits > > self.draw() > > self.ax_background = self.copy_from_bbox(self.ax.bbox) > > self.blit(self.figure.bbox) > > > > # just draw the animated artist > > self.ax.draw_artist(self.sin_line) > > self.ax.draw_artist(self.cos_line) > > # just redraw the axes rectangle > > self.blit(self.ax.bbox) > > if self.cnt == 0: > > # TODO: this shouldn't be necessary, but if it is excluded the > > # canvas outside the axes is not initially painted. > > self.draw() > > if self.cnt==ITERS: > > # print the timing info and quit > > print 'FPS:' , ITERS/(time.time()self.tstart) > > #sys.exit() > > self.killTimer(self.maintimer) > > else: > > self.cnt += 1 > > app = QtGui.QApplication(sys.argv) > > widget = BlitQT() > > widget.show() > > sys.exit(app.exec_()) > > Gerald, I haven't looked at your code, but I would like to point out that if you wish to experiment a little further with animations in matplotlib, there is a animation module that is in the current development branch (but has not been officially released). Maybe using it might help make your code less "hackish"? We would also greatly welcome any and all comments on the module before the next release of matplotlib. Ben Root 