Add test for #rrggbbaa roundtrip; add whatsnew.

anntzer · anntzer · commit d492ba4604e4 · 2016-05-14T12:36:44.000-07:00
diff --git a/doc/users/whats_new/rgba-support.rst b/doc/users/whats_new/rgba-support.rst
@@ -0,0 +1,11 @@
+Improved color conversion API and RGBA support
+----------------------------------------------
+
+The :module:`~matplotlib.colors` gained a new color conversion API with
+full support for the alpha channel.  The main public functions are
+:func:`~matplotlib.colors.is_color_like`, :func:`matplotlib.colors.to_rgba`,
+:func:`matplotlib.colors.to_rgba_array` and :func:`~matplotlib.colors.to_hex`.
+RGBA quadruplets are encoded in hex format as `#rrggbbaa`.
+
+A side benefit is that the Qt options editor now allows setting the alpha
+channel of the artists as well.
diff --git a/lib/matplotlib/tests/test_colors.py b/lib/matplotlib/tests/test_colors.py
@@ -623,6 +623,9 @@ def test_conversions():
     assert_equal(mcolors.to_rgba((1, 1, 1), .5), (1, 1, 1, .5))
     # builtin round differs between py2 and py3.
     assert_equal(mcolors.to_hex((.7, .7, .7)), "#b2b2b2ff")
+    # hex roundtrip.
+    hex_color = "#1234abcd"
+    assert_equal(mcolors.to_hex(mcolors.to_rgba(hex_color)), hex_color)
 
 
 if __name__ == '__main__':
