Colorbar edges are different in PDF backend

[mdboom]

This is a reopening of #1444, since it still hasn't found a satisfactory solution.

In a message on matplotlib-users from Andrew Dawson:

Hi all,

I just noticed that colorbar edges are drawn in white when output in PDF and black when output in PNG. A small test script is attached along with the output to show the difference.

I'd be interested in knowing if others can reproduce this? I'm using mpl-1.3.x (updated 5 minutes ago) on 64-bit Ubuntu 12.04.

Cheers,
Andrew

import matplotlib.pyplot as plt
import numpy as np

# dummy data
x = y = np.linspace(-np.pi, np.pi, 50)
X, Y = np.meshgrid(x, y)
Z = np.sin(X) * np.cos(2.*Y)

# draw a filled contour plot and add a colorbar with drawedges turned on
contours = plt.contourf(x, y, Z)
cb = plt.colorbar(orientation='horizontal', drawedges=True)

# turn off tick marks so the edges can be seen
for tick in cb.ax.get_xticklines() + cb.ax.get_yticklines():
    tick.set_visible(False)

# save as a PDF and a PNG
plt.savefig('test.pdf')
plt.savefig('test.png')

[mdboom]

In my original solution, I had forgotten that a GraphicsContextPdf actually as push and pop, and that's really what should have been used to save/restore the graphics state. This seems to work now, and all tests are passing. If anyone else wants to test this out, that would be great -- and I'm sure Travis will give us some results momentarily.

[dmcdougall]

I tested this out. It works for me, too! Good work @mdboom

[dmcdougall]

@mdboom Can you squash this down to a single commit?

[mdboom]

Thanks. Squashed.

[dmcdougall]

Thanks.