Fill color is always opaque in the pdf backend if there is a hatch pattern #3841
Closed as not planned
Description
I've posted this issue on StackOverflow as: http://stackoverflow.com/questions/27094747/
The basic problem is that transparency information isn't being correctly to PDFs when hatching is used.
I'm running in OS X (Yosemite) with the default MacOSX matplotlib backend and using matplotlib 1.4.1. Is there any reason why this setup should fail to produce transparent PDF output? This used to work in the past (with OS X Mavericks and an earlier version of matplotlib) but I'm not sure exactly what change has caused this problem.
If the following code is run, the problem can be seen in with_hatch.pdf, but not in any of the other output files.
#! /usr/bin/env python
import matplotlib.pyplot as plt
fig = plt.figure( figsize=(6, 6), dpi=100, facecolor='white' )
ax = fig.add_axes( [0.15, 0.1, 0.8, 0.85] )
bin_edges = [0.0, 0.5, 0.5, 1.0, 1.0, 1.5, 1.5, 2.0, 2.0, 2.5, 2.5, 3.0, 3.0, 3.5, 3.5, 4.0, 4.0, 4.5, 4.5, 5.0, 5.0, 5.5, 5.5, 6.0, 6.0, 7.0, 7.0, 8.0]
y_low = [0.9581631739289882, 0.9581631739289882, 0.8966054746563691, 0.8966054746563691, 0.8369962202270926, 0.8369962202270926, 0.7824880045351325, 0.7824880045351325, 0.7231695683685057, 0.7231695683685057, 0.6673767757896321, 0.6673767757896321, 0.6083447707111752, 0.6083447707111752, 0.5602384968623321, 0.5602384968623321, 0.5109567893600544, 0.5109567893600544, 0.4707872827805316, 0.4707872827805316, 0.4304527769718274, 0.4304527769718274, 0.39024135798617826, 0.39024135798617826, 0.3593458738615755, 0.3593458738615755, 0.3275704585658484, 0.3275704585658484]
y_high = [0.9762065896798683, 0.9762065896798683, 0.9227253843496172, 0.9227253843496172, 0.8738222849514, 0.8738222849514, 0.8299500683866315, 0.8299500683866315, 0.7810616940586165, 0.7810616940586165, 0.7357506442258693, 0.7357506442258693, 0.6852756294051707, 0.6852756294051707, 0.6441575476130643, 0.6441575476130643, 0.5987788803224889, 0.5987788803224889, 0.5630257208701298, 0.5630257208701298, 0.5274860424153797, 0.5274860424153797, 0.4915335923551736, 0.4915335923551736, 0.46502435263727837, 0.46502435263727837, 0.43196895235913746, 0.43196895235913746]
ax.fill_between( bin_edges, y_low, y_high, facecolor='green', edgecolor='white', alpha=0.4 )
plt.savefig( 'without_hatch.pdf' )
plt.savefig( 'without_hatch.png' )
ax.fill_between( bin_edges, y_low, y_high, facecolor='green', edgecolor='white', hatch='xxxx', alpha=0.4 )
plt.savefig( 'with_hatch.pdf' )
plt.savefig( 'with_hatch.png' )