Put all clippaths in their own def at the end of the file so that they are accessible even when their referents are made invisible. Problem pointed out by David Huard on the mailing list in thread "Adding interactivity to an histogram in SVG".

mdboom · mdboom · commit 0d4a2e16a654 · 2011-08-23T11:20:20.000-04:00
diff --git a/lib/matplotlib/backends/backend_svg.py b/lib/matplotlib/backends/backend_svg.py
@@ -279,6 +279,8 @@ def __init__(self, width, height, svgwriter, basename=None):
         self._write_default_style()
 
     def finalize(self):
+        self._write_clips()
+        self._write_hatches()
         self._write_svgfonts()
         self.writer.close(self._start_id)
 
@@ -321,26 +323,35 @@ def _get_hatch(self, gc, rgbFace):
         """
         Create a new hatch pattern
         """
-        writer = self.writer
-        HATCH_SIZE = 72
         dictkey = (gc.get_hatch(), rgbFace, gc.get_rgb())
         oid = self._hatchd.get(dictkey)
         if oid is None:
             oid = self._make_id('h', dictkey)
-            writer.start('defs')
+            self._hatchd[dictkey] = ((gc.get_hatch_path(), rgbFace, gc.get_rgb()), oid)
+        else:
+            _, oid = oid
+        return oid
+        
+    def _write_hatches(self):
+        if not len(self._hatchd):
+            return
+        HATCH_SIZE = 72
+        writer = self.writer
+        writer.start('defs')
+        for ((path, face, stroke), oid) in self._hatchd.values():
             writer.start(
                 'pattern',
                 id=oid,
                 patternUnits="userSpaceOnUse",
                 x="0", y="0", width=str(HATCH_SIZE), height=str(HATCH_SIZE))
             path_data = self._convert_path(
-                gc.get_hatch_path(),
+                path,
                 Affine2D().scale(HATCH_SIZE).scale(1.0, -1.0).translate(0, HATCH_SIZE),
                 simplify=False)
-            if rgbFace is None:
+            if face is None:
                 fill = 'none'
             else:
-                fill = rgb2hex(rgbFace)
+                fill = rgb2hex(face)
             writer.element(
                 'rect',
                 x="0", y="0", width=str(HATCH_SIZE+1), height=str(HATCH_SIZE+1),
@@ -349,17 +360,15 @@ def _get_hatch(self, gc, rgbFace):
                 'path',
                 d=path_data,
                 style=generate_css({
-                    'fill': rgb2hex(gc.get_rgb()),
-                    'stroke': rgb2hex(gc.get_rgb()),
+                    'fill': rgb2hex(stroke),
+                    'stroke': rgb2hex(stroke),
                     'stroke-width': str(1.0),
                     'stroke-linecap': 'butt',
                     'stroke-linejoin': 'miter'
                     })
                 )
             writer.end('pattern')
-            writer.end('defs')
-            self._hatchd[dictkey] = oid
-        return oid
+        writer.end('defs')
 
     def _get_style(self, gc, rgbFace):
         """
@@ -409,22 +418,34 @@ def _get_clip(self, gc):
         else:
             return None
 
-        oid = self._clipd.get(dictkey)
-        if oid is None:
-            writer = self.writer
+        clip = self._clipd.get(dictkey)
+        if clip is None:
             oid = self._make_id('p', dictkey)
-            writer.start('defs')
-            writer.start('clipPath', id=oid)
             if clippath is not None:
+                self._clipd[dictkey] = ((clippath, clippath_trans), oid)
+            else:
+                self._clipd[dictkey] = (dictkey, oid)
+        else:
+            clip, oid = clip
+        return oid
+
+    def _write_clips(self):
+        if not len(self._clipd):
+            return
+        writer = self.writer
+        writer.start('defs')
+        for clip, oid in self._clipd.values():
+            writer.start('clipPath', id=oid)
+            if len(clip) == 2:
+                clippath, clippath_trans = clip
                 path_data = self._convert_path(clippath, clippath_trans, simplify=False)
                 writer.element('path', d=path_data)
             else:
+                x, y, w, h = clip
                 writer.element('rect', x=str(x), y=str(y), width=str(w), height=str(h))
             writer.end('clipPath')
-            writer.end('defs')
-            self._clipd[dictkey] = oid
-        return oid
-
+        writer.end('defs')
+    
     def _write_svgfonts(self):
         if not rcParams['svg.fonttype'] == 'svgfont':
             return
