MacOSX backend incorrectly displays plot/scatter under Affine2D transform

[jdgleeson]

The default MacOSX backend does not display the expected output for the following code. Both the QT4Agg and TkAgg backends display correctly.

Code illustrating the problem:

# from matplotlib import use
# use("QT4Agg")
# use("TkAgg")
import matplotlib.pyplot as plt
import matplotlib.transforms as mtrans
import numpy as np

plt.figure()
ax = plt.subplot(111)
base_trans = ax.transData
mtx = np.array([[1,1,0], 
                [0,1,0], 
                [0,0,1]])
tr = mtrans.Affine2D(matrix=mtx) + base_trans

plt.plot([1,2,3], [1,2,3], 'gray', transform=tr)
plt.scatter([1,2,3], [1,2,3], c='k', marker='D', transform=tr)
plt.show()

Environment:

>>> import matplotlib
>>> matplotlib.__version__
'1.2.0'
>>> matplotlib.__file__
'/opt47/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/__init__.pyc'
>>> matplotlib.get_configdir()
'/Users/jdgleeson/.matplotlib'
>>> matplotlib.get_backend()
'MacOSX'

TkAgg.png showing expected results (via X11 on my Mac).

MacOSX.png shows incorrect results.

[goldnd]

The same thing happens with quiver plots.

[pelson]

Thanks for reporting @jdgleeson (and the comment @goldnd).

[mdboom]

@mdehoon: Any thoughts?

[mdehoon]

It looks like b and c in the function _transformation_converter in src/_macosx.m should be switched.
@jdgleeson @goldnd , could you try this and do some tests?

[jdgleeson]

On 2013-04-09, at 2:03 AM, mdehoon wrote:

It looks like b and c in the function _transformation_converter in
src/_macosx.m should be switched.
@jdgleeson @goldnd , could you try this and do some tests?

That fixed it for me! Thanks.

--- src/_macosx.m.orig 2012-11-08 09:38:38.000000000 -0700
+++ src/_macosx.m 2013-04-09 09:17:37.000000000 -0600
@@ -1205,8 +1205,8 @@
return 0;
}
const double a = (double)PyArray_GETPTR2(object, 0, 0);

• const double b = (double)PyArray_GETPTR2(object, 0, 1);
• const double c = (double)PyArray_GETPTR2(object, 1, 0);
• const double c = (double)PyArray_GETPTR2(object, 0, 1);
• const double b = (double)PyArray_GETPTR2(object, 1, 0);
  const double d = (double)PyArray_GETPTR2(object, 1, 1);
  const double tx = (double)PyArray_GETPTR2(object, 0, 2);
  const double ty = (double)PyArray_GETPTR2(object, 1, 2);

[mdehoon]

@jdgleeson Thanks for trying this fix. Could you also try the other matplotlib examples to make sure this doesn't introduce some new bug?

[jdgleeson]

On 2013-04-09, at 6:41 PM, mdehoon wrote:

@jdgleeson Thanks for trying this fix. Could you also try the other
matplotlib examples to make sure this doesn't introduce some new bug?

Ran 1214 tests in 973.796s

FAILED (KNOWNFAIL=300, SKIP=3, failures=2)

Sorry for the delay; I was trying to install Inkscape and ran into a
problem building a dependency.

The two failures are in

FAIL: matplotlib.tests.test_text.test_font_styles.test

ImageComparisonFailure: images not close: /Users/jdgleeson/
result_images/test_text/font_styles.png vs. /Users/jdgleeson/
result_images/test_text/font_styles-expected.png (RMS 47.353)

ImageComparisonFailure: images not close: /Users/jdgleeson/
result_images/test_text/font_styles_pdf.png vs. /Users/jdgleeson/
result_images/test_text/font_styles-expected_pdf.png (RMS 23.423)

In both cases, all fonts look the same as "Normal Font"

I found this issue which may explain it.
macosx backend doesn't find fonts the same way as other backends
#781

[mdehoon]

@jdgleeson Thanks! Then at least we know that this fix doesn't introduce new problems, as
the two test failures are not related to the current issue.