HI to the list,
I'm playing with blit animations in a gtk window. Looking at MPL
examples I came up with a working example (attached) that shows a sin
wave with a play toggle button and a "scale" button that changes the
axis limits. In order to plot the first frame (before play is clicked)
and to correctly implement the scale action I've written the "refresh"
method that follows:
def refresh(self):
# This explicit draw is needed to draw the grid and to save a clean
# background
self.canvas.draw()
self.background = self.canvas.copy_from_bbox(self.ax.bbox)
# This draw is needed to draw the stand-still plot (first frame)
self.line.set_animated(False)
self.canvas.draw()
self.line.set_animated(True)
# NOTE: Saving the background here would save the line too so I have
# to call canvas.draw() two times
This (quite redundant) implementation works. However, (QUESTION 1) is
it expected that the following straightforward implementation:
def refresh(self):
self.line.set_animated(False)
self.canvas.draw()
self.line.set_animated(True)
self.background = self.canvas.copy_from_bbox(self.ax.bbox)
saves in background also the line? So in this case I would have the
animation superimposed to the first frame? Seems like a bug...
Is there a better way to achieve the same result?
Furthermore, I want to attach the refresh method to some events in
order to refresh the plot event if play is not active. For example
zooming or panning with the matplotlib toolbar buttons makes the plot
disappear. (QUESTION 2) Is there such event I can use to have the line
plotted? Or is better to implement this changing from an animated to a
still state? In this latter case once I plot with animated=False I'm
not able anymore to save a clean background without the line (event
using the line.set_animated(True) method before copying the bg).
When we have solved this file could be a nice reference example.
Thanks,
~ Antonio
#!/usr/bin/env python
import gtk
import gobject
import numpy as np
from matplotlib.figure import Figure
from matplotlib.backends.backend_gtkagg import FigureCanvasGTKAgg as FigureCanvas
from matplotlib.backends.backend_gtk import NavigationToolbar2GTK as NavigationToolbar
##
# Simple GTK windows base classes
#
class BaseWindow:
"""A base gtk window that can be closed."""
def __init__(self):
self.window = gtk.Window(gtk.WINDOW_TOPLEVEL)
self.window.set_default_size(550, 500)
self.window.connect("delete_event", self.on_delete_event)
self.window.connect("destroy", self.on_destroy)
def main(self):
gtk.main()
def on_delete_event(self, widget, *args):
return False
def on_destroy(self, widget, data=None):
gtk.main_quit()
class PlotWindow(BaseWindow):
"""A gtk window with a figure inside."""
def __init__(self, show=True, create_axis=False):
BaseWindow.__init__(self)
self.figure = Figure()
self.canvas = FigureCanvas(self.figure)
if create_axis: self.ax = self.figure.add_subplot(111)
self.toolbar = NavigationToolbar(self.canvas, self.window)
self.vbox = gtk.VBox()
self.vbox.pack_start(self.toolbar, expand=False)
self.vbox.pack_start(self.canvas, expand=True)
self.window.add(self.vbox)
if show: self.window.show_all()
##
# The main application
#
class Plotter(PlotWindow):
def __init__(self):
PlotWindow.__init__(self, create_axis=True, show=False)
# Add two buttons to the toolbar: scale and play
self.scalebutton = gtk.ToolButton(gtk.STOCK_ZOOM_FIT)
self.scalebutton.connect("clicked", self.scale_clicked)
self.toolbar.insert(self.scalebutton, 0)
self.playbutton = gtk.ToggleToolButton(gtk.STOCK_MEDIA_PLAY)
self.playbutton.set_active(False)
self.playbutton.connect("clicked", self.play_toggled)
self.toolbar.insert(self.playbutton, 0)
self.window.show_all()
# Create the plot, the first frame (note that animated=True)
self.t = np.arange(100)*0.1
self.line, = self.ax.plot(self.t, np.sin(self.t), animated=True)
self.ax.grid(True)
# Finalize the plot
self.refresh()
self.n = 0
self.main() # Start the gtk main loop
def refresh_wrong(self):
self.line.set_animated(False)
self.canvas.draw()
self.line.set_animated(True)
self.background = self.canvas.copy_from_bbox(self.ax.bbox)
def refresh(self):
# This explicit draw is needed to draw the grid and to save a clean
# background
self.canvas.draw()
self.background = self.canvas.copy_from_bbox(self.ax.bbox)
# This draw is needed to draw the stand-still plot (first frame)
self.line.set_animated(False)
self.canvas.draw()
self.line.set_animated(True)
# NOTE: Saving the background here would save the line too
def play_toggled(self, widget):
if self.playbutton.get_active():
self.gid = gobject.timeout_add(50, self.update_fast)
else:
gobject.source_remove(self.gid)
def scale_clicked(self, widget):
x, y = self.line.get_xdata(), self.line.get_ydata()
self.ax.set_ylim([y.min()*2, y.max()*2])
self.ax.set_xlim([x.min()-2, x.max()+2])
self.refresh()
def update_slow(self):
"""This is the classic update, not suitable for animations."""
self.n += 1
self.line.set_ydata(np.sin(self.t+self.n*0.1))
self.canvas.draw()
return True
def update_fast(self):
"""The fast (blit) update to be used in animations."""
self.n += 1
# restore the clean slate background
self.canvas.restore_region(self.background)
# update the data
self.line.set_ydata(np.sin(self.t+self.n*0.1))
# just draw the animated artist
self.ax.draw_artist(self.line)
# just redraw the axes rectangle
self.canvas.blit(self.ax.bbox)
return True
if __name__ == "__main__":
Plotter()
------------------------------------------------------------------------------
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