blocking UI functions cause figure size to change  #10566

import imageio
import numpy as np

FORCE_IMAGE_RESIZE_ON_PAUSE = False

# Switch backends
import matplotlib
if False:
  matplotlib.use("Qt5Agg")
else:
  matplotlib.use("TkAgg")

import matplotlib.pyplot as plt

import matplotlib
from sys import platform, version
print("backend     ", matplotlib.get_backend() )
print("matplotlib  ", matplotlib.__version__)
print("python      ", version.split(" ")[0])
print("OS          ", platform)


class Figure:
  size_figure_inches = 8.0 #< size of full figure
  size_world_half = 2 #< size of world (centered 0)

  def __init__(self, fid):
    self.fig = plt.figure(fid)
    self.canvas = self.fig.canvas

    #--- specify figure
    sfi = self.size_figure_inches
    self.fig.set_size_inches(sfi, sfi)
    self.fig.set_dpi(100)

    # --- specify axis
    self.ax = self.fig.add_axes([0, 0, 1, 1])  # < (full image)

  # TODO bug https://github.com/matplotlib/matplotlib/issues/10566
  def pause(self, time):
    plt.pause(time)
    if FORCE_IMAGE_RESIZE_ON_PAUSE:
      sfi = self.size_figure_inches
      self.fig.set_size_inches(sfi, sfi)

  def plot2(self, P):
    x = P[:, 0]
    y = P[:, 1]
    self.ax.plot(x, y)

#------------------------------------------------------------------------------------------

t = np.arange(0.0, 2.0, 0.01)
s = 1 + np.sin(2*np.pi*t)
x = np.cos(2*np.pi*t)
y = np.sin(2*np.pi*t)
M_restpose = np.vstack([x,y]).transpose()

fig = Figure(1)
offs = np.arange(-1, +1, 1)
for i, off in enumerate(offs):
  print("(1) Figure size for test%d " % i, fig.fig.get_size_inches())
  fig.ax.cla()
  print("(2) Figure size for test%d " % i, fig.fig.get_size_inches())
  fig.plot2(M_restpose)
  print("(3) Figure size for test%d " % i, fig.fig.get_size_inches())
  fig.fig.savefig("./test%d.png" % i)
  print("    Png size:", imageio.imread("./test%d.png"%i).shape)
  print("(4) Figure size for test%d " % i, fig.fig.get_size_inches())
  fig.pause(1)
  print("(5) Figure size for test%d " % i, fig.fig.get_size_inches())
  print("\n")