optional user defined svg hash salt

klaus · klaus · commit 2181f7eaa3f2 · 2015-12-10T19:01:27.000+01:00
diff --git a/doc/users/whats_new/rcparams.rst b/doc/users/whats_new/rcparams.rst
@@ -0,0 +1,5 @@
+Added ``svg.hashsalt`` key to rcParams
+```````````````````````````````````````
+If ``svg.hashsalt`` is ``None`` (which it is by default), the svg backend uses ``uuid4`` to generate the hash salt.
+If it is not ``None``, it must be a string that is used as the hash salt instead of ``uuid4``.
+This allows for deterministic SVG output.
diff --git a/lib/matplotlib/backends/backend_svg.py b/lib/matplotlib/backends/backend_svg.py
@@ -308,7 +308,10 @@ def _write_default_style(self):
 
     def _make_id(self, type, content):
         content = str(content)
-        salt = str(uuid.uuid4())
+        if rcParams['svg.hashsalt'] is None: 
+            salt = str(uuid.uuid4())
+        else:
+            salt = rcParams['svg.hashsalt']
         if six.PY3:
             content = content.encode('utf8')
             salt = salt.encode('utf8')
diff --git a/lib/matplotlib/rcsetup.py b/lib/matplotlib/rcsetup.py
@@ -1165,6 +1165,7 @@ def validate_hist_bins(s):
     # True to save all characters as paths in the SVG
     'svg.embed_char_paths': [True, deprecate_svg_embed_char_paths],
     'svg.fonttype':         ['path', validate_svg_fonttype],
+    'svg.hashsalt':         [None, validate_any],
 
     # set this when you want to generate hardcopy docstring
     'docstring.hardcopy': [False, validate_bool],
