I find the get_window_extent method for the image object gives all zeros.
for example
import numpy as np
import matplotlib.pyplot as plt
im = np.array([[0.25, 0.75, 1.0, 0.75], [0.1, 0.65, 0.5, 0.4], \
[0.6, 0.3, 0.0, 0.2], [0.7, 0.9, 0.4, 0.6]])
fig = plt.figure()
ax = plt.subplot()
ax.set_xlim(0,1)
ax.set_ylim(0,1)
im_obj = ax.imshow(im, extent = [0.25, 0.75, 0.25, 0.75], interpolation = 'nearest')
displays the following graph
Now I want to get the image size in display coordinates, so I do the following:
fig.canvas.draw()
renderer = fig.canvas.renderer
im_bbox = im_obj.get_window_extent(renderer)
The problem print im_bboxis causing Bbox('array([[ 0., 0.],\n [ 0., 0.]])'). The method .get_window_extent(renderer)works fine with text, lines and patches, so I was a little surprised to see that it does not work with images. Is this a mistake, or am I doing something wrong?
In case that matters, I use Matplotlib 1.3.0 with the TkAgg backend.
EDIT:
Here is the work to get the frame of the image in the displayed coordinates
im_ext = im_obj.get_extent()
im_pts = np.array([[im_ext[0], im_ext[2]], [im_ext[1], im_ext[3]]])
bbox = mpl.transforms.Bbox(im_pts)
fig.canvas.draw()
bbox = bbox.transformed(ax.transData)
Now print bboxcreates Bbox('array([[ 236.375, 148.2 ],\n [ 433.975, 345.8 ]])'). I also confirmed that these values are correct. The following code:
from matplotlib.patches import Rectangle
rect = Rectangle([bbox.x0, bbox.y0], \
bbox.width, bbox.height, \
linewidth = 8, color = [1,0,0], \
fill = False)
fig.patches.append(rect)
fig.canvas.draw()
plt.savefig('wtf.png', dpi = mpl.rcParams['figure.dpi'])
displays the following graph
, . , , fig.canvas.draw(), (). fig.canvas.draw() . , matplotlib , , .
, . im_obj.get_window_extent(renderer) ?