Add basic support for SVG fonts -- supported by Chrome, Safari and Opera

Author: mdboom

lib/matplotlib/backends/backend_svg.py

@@ -261,6 +261,7 @@ def __init__(self, width, height, svgwriter, basename=None):
         self._hatchd = {}
         self._has_gouraud = False
         self._n_gradients = 0
+        self._fonts = {}
         self.mathtext_parser = MathTextParser('SVG')
 
         RendererBase.__init__(self)
@@ -277,6 +278,7 @@ def __init__(self, width, height, svgwriter, basename=None):
         self._write_default_style()
 
     def finalize(self):
+        self._write_svgfonts()
         self.writer.close(self._start_id)
 
     def _write_default_style(self):
@@ -422,6 +424,40 @@ def _get_clip(self, gc):
             self._clipd[dictkey] = oid
         return oid
 
+    def _write_svgfonts(self):
+        if not rcParams['svg.fonttype'] == 'svgfont':
+            return
+
+        writer = self.writer
+        writer.start('defs')
+        for font_fname, chars in self._fonts.items():
+            font = FT2Font(font_fname)
+            font.set_size(72, 72)
+            sfnt = font.get_sfnt()
+            writer.start('font', id=sfnt[(1, 0, 0, 4)])
+            writer.element(
+                'font-face',
+                attrib={
+                    'font-family': font.family_name,
+                    'font-style': font.style_name,
+                    'units-per-em': '72',
+                    'bbox': ' '.join(str(x / 64.0) for x in font.bbox)})
+            for char in chars:
+                glyph = font.load_char(char, flags=LOAD_NO_HINTING)
+                verts, codes = font.get_path()
+                path = Path(verts, codes)
+                path_data = self._convert_path(path, None)
+                # name = font.get_glyph_name(char)
+                writer.element(
+                    'glyph',
+                    d=path_data,
+                    attrib={
+                        # 'glyph-name': name,
+                        'unicode': unichr(char),
+                        'horiz-adv-x': str(glyph.linearHoriAdvance / 65536.0)})
+            writer.end('font')
+        writer.end('defs')
+
     def open_group(self, s, gid=None):
         """
         Open a grouping element with label *s*. If *gid* is given, use
@@ -867,6 +903,11 @@ def _draw_text_as_text(self, gc, x, y, s, prop, angle, ismath):
                 ('rotate', (-angle,))])
 
             writer.element('text', s, attrib=attrib)
+
+            if rcParams['svg.fonttype'] == 'svgfont':
+                fontset = self._fonts.setdefault(font.fname, set())
+                for c in s:
+                    fontset.add(ord(c))
         else:
             writer.comment(s)
 
@@ -894,11 +935,17 @@ def _draw_text_as_text(self, gc, x, y, s, prop, angle, ismath):
             for font, fontsize, thetext, new_x, new_y, metrics in svg_glyphs:
                 style = generate_css({
                     'font-size': str(fontsize),
-                    'font-family': font.family_name})
+                    'font-family': font.family_name,
+                    'font-style': font.style_name})
                 if thetext == 32:
                     thetext = 0xa0 # non-breaking space
                 spans.setdefault(style, []).append((new_x, -new_y, thetext))
 
+            if rcParams['svg.fonttype'] == 'svgfont':
+                for font, fontsize, thetext, new_x, new_y, metrics in svg_glyphs:
+                    fontset = self._fonts.setdefault(font.fname, set())
+                    fontset.add(thetext)
+
             for style, chars in spans.items():
                 chars.sort()
 
@@ -948,7 +995,7 @@ def draw_text(self, gc, x, y, s, prop, angle, ismath):
             self.writer.start(
                 'g', attrib={'clip-path': 'url(#%s)' % clipid})
 
-        if rcParams['svg.embed_char_paths']:
+        if rcParams['svg.fonttype'] == 'path':
             self._draw_text_as_path(gc, x, y, s, prop, angle, ismath)
         else:
             self._draw_text_as_text(gc, x, y, s, prop, angle, ismath)

lib/matplotlib/rcsetup.py

@@ -305,6 +305,11 @@ def validate_tkpythoninspect(s):
   'center',
 ], ignorecase=True)
 
+def deprecate_svg_embed_char_paths(value):
+    warnings.warn("svg.embed_char_paths is deprecated.  Use svg.fonttype instead.")
+
+validate_svg_fonttype = ValidateInStrings('fonttype', ['none', 'path', 'svgfont'])
+
 class ValidateInterval:
     """
     Value must be in interval
@@ -530,7 +535,8 @@ def __call__(self, s):
     'pdf.fonttype'      : [3, validate_fonttype],  # 3 (Type3) or 42 (Truetype)
     'svg.image_inline'  : [True, validate_bool],    # write raster image data directly into the svg file
     'svg.image_noscale' : [False, validate_bool],  # suppress scaling of raster data embedded in SVG
-    'svg.embed_char_paths' : [True, validate_bool],  # True to save all characters as paths in the SVG
+    'svg.embed_char_paths' : [True, deprecate_svg_embed_char_paths],  # True to save all characters as paths in the SVG
+    'svg.fonttype' : ['path', validate_svg_fonttype],
 
     'docstring.hardcopy' : [False, validate_bool],  # set this when you want to generate hardcopy docstring
     'plugins.directory' : ['.matplotlib_plugins', str], # where plugin directory is locate

matplotlibrc.template

@@ -329,7 +329,11 @@ backend      : %(backend)s
 # svg backend params
 #svg.image_inline : True       # write raster image data directly into the svg file
 #svg.image_noscale : False     # suppress scaling of raster data embedded in SVG
-#svg.embed_char_paths : True       # embed character outlines in the SVG file
+#svg.fonttype : 'path'         # How to handle SVG fonts:
+#    'none': Assume fonts are installed on the machine where the SVG will be viewed.
+#    'path': Embed characters as paths -- supported by most SVG renderers
+#    'svgfont': Embed characters as SVG fonts -- supported only by Chrome,
+#               Opera and Safari
 
 # docstring params
 #docstring.hardcopy = False  # set this when you want to generate hardcopy docstring