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pelsonpelson
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Fixed background colour of PNGs saved with a non-zero opacity.
1 parent d94036c commit d8fce7b

8 files changed

Lines changed: 125 additions & 7 deletions

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‎doc/users/whats_new.rst‎

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Original file line numberDiff line numberDiff line change
@@ -166,6 +166,11 @@ Multiple images on same axes are correctly transparent
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When putting multiple images onto the same axes, the background color
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of the axes will now show through correctly.
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Full control of the background color
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------------------------------------
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Phil Elson fixed the Agg backend such that PNGs are now saved with the correct
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background color when :meth:`fig.patch.get_alpha` is not 1.
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.. _whats-new-1-2:
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new in matplotlib-1.2

‎lib/matplotlib/backends/backend_agg.py‎

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Original file line numberDiff line numberDiff line change
@@ -16,9 +16,8 @@
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TODO:
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* allow save to file handle
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* integrate screen dpi w/ ppi and text
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"""
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from __future__ import division
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import threading
@@ -438,7 +437,7 @@ def draw(self):
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"""
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if __debug__: verbose.report('FigureCanvasAgg.draw', 'debug-annoying')
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441-
self.renderer = self.get_renderer()
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self.renderer = self.get_renderer(cleared=True)
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# acquire a lock on the shared font cache
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RendererAgg.lock.acquire()
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@@ -449,7 +448,7 @@ def draw(self):
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452-
def get_renderer(self):
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def get_renderer(self, cleared=False):
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l, b, w, h = self.figure.bbox.bounds
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key = w, h, self.figure.dpi
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try: self._lastKey, self.renderer
@@ -459,6 +458,8 @@ def get_renderer(self):
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if need_new_renderer:
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self.renderer = RendererAgg(w, h, self.figure.dpi)
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self._lastKey = key
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elif cleared:
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self.renderer.clear()
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return self.renderer
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def tostring_rgb(self):

‎lib/matplotlib/backends/backend_pdf.py‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -436,7 +436,7 @@ def __init__(self, filename):
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revision = ''
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self.infoDict = {
439-
'Creator': 'matplotlib %s, http://matplotlib.sf.net' % __version__,
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'Creator': 'matplotlib %s, http://matplotlib.org' % __version__,
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'Producer': 'matplotlib pdf backend%s' % revision,
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'CreationDate': datetime.today()
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}

‎lib/matplotlib/tests/baseline_images/test_figure/alpha_background.png‎

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‎lib/matplotlib/tests/baseline_images/test_figure/alpha_background.svg‎

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‎lib/matplotlib/tests/test_agg.py‎

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Original file line numberDiff line numberDiff line change
@@ -1,6 +1,50 @@
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from __future__ import print_function
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import os
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import tempfile
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from numpy.testing import assert_array_almost_equal
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9+
10+
from matplotlib.image import imread
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from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
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from matplotlib.figure import Figure
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from matplotlib.testing.decorators import cleanup
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@cleanup
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def test_repeated_save_with_alpha():
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# We want an image which has a background color of blue, with an
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# alpha of 0.25.
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fig = Figure([1, 0.4])
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canvas = FigureCanvas(fig)
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fig.set_facecolor((0, 0, 0.4))
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fig.patch.set_alpha(0.25)
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# The target color is fig.patch.get_facecolor()
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_, img_fname = tempfile.mkstemp(suffix='.png')
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try:
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fig.savefig(img_fname,
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facecolor=fig.get_facecolor(),
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edgecolor='none')
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# Save the figure again to check that the
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# colors don't bleed from the previous renderer.
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fig.savefig(img_fname,
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facecolor=fig.get_facecolor(),
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edgecolor='none')
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# Check the first pixel has the desired color & alpha
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# (approx: 0, 0, 0.1, 0.25)
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assert_array_almost_equal(tuple(imread(img_fname)[0, 0]),
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(0.0, 0.0, 0.098, 0.250),
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decimal=3)
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finally:
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os.remove(img_fname)
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549
def report_memory(i):
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pid = os.getpid()
@@ -64,3 +108,8 @@ def report_memory(i):
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## # w/o text and w/o write_png: Average memory consumed per loop: 0.02
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## # w/o text and w/ write_png : Average memory consumed per loop: 0.3400
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## # w/ text and w/ write_png : Average memory consumed per loop: 0.32
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if __name__ == "__main__":
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import nose
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nose.runmodule(argv=['-s', '--with-doctest'], exit=False)

‎lib/matplotlib/tests/test_figure.py‎

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Original file line numberDiff line numberDiff line change
@@ -74,6 +74,22 @@ def test_suptitle():
7474
fig.suptitle('title', color='g', rotation='30')
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7676

77+
@image_comparison(baseline_images=['alpha_background'],
78+
extensions=['png', 'svg'], # PDF is wrong
79+
savefig_kwarg={'facecolor': 'black', 'edgecolor': 'none'})
80+
def test_alpha():
81+
# We want an image which has a background color of black, with an
82+
# alpha of 0.3.
83+
fig = plt.figure(figsize=[2, 1])
84+
fig.set_facecolor('black')
85+
fig.patch.set_alpha(0.3)
86+
87+
import matplotlib.patches as mpatches
88+
fig.patches.append(mpatches.CirclePolygon([20, 20],
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radius=15,
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facecolor='red'))
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92+
7793
if __name__ == "__main__":
7894
import nose
7995
nose.runmodule(argv=['-s', '--with-doctest'], exit=False)

‎src/_backend_agg.cpp‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -411,7 +411,7 @@ RendererAgg::RendererAgg(unsigned int width, unsigned int height, double dpi,
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renderingBuffer.attach(pixBuffer, width, height, stride);
412412
pixFmt.attach(renderingBuffer);
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rendererBase.attach(pixFmt);
414-
rendererBase.clear(agg::rgba(1, 1, 1, 0));
414+
rendererBase.clear(agg::rgba(0, 0, 0, 0));
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rendererAA.attach(rendererBase);
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rendererBin.attach(rendererBase);
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hatchRenderingBuffer.attach(hatchBuffer, HATCH_SIZE, HATCH_SIZE,
@@ -2388,7 +2388,7 @@ RendererAgg::clear(const Py::Tuple& args)
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_VERBOSE("RendererAgg::clear");
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23902390
args.verify_length(0);
2391-
rendererBase.clear(agg::rgba(1, 1, 1, 0));
2391+
rendererBase.clear(agg::rgba(0, 0, 0, 0));
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23932393
return Py::Object();
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}

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