Align inline mathtext correctly in HTML docs (by adjusting for the baseline)

mdboom · mdboom · commit 2d43e5b07cc6 · 2008-06-17T15:42:12.000Z
svn path=/trunk/matplotlib/; revision=5577
diff --git a/doc/sphinxext/mathpng.py b/doc/sphinxext/mathpng.py
@@ -113,16 +113,19 @@ def latex2png(latex, name):
 
 # This uses mathtext to render the expression
 def latex2png(latex, filename, fontset='cm'):
+    latex = "$%s$" % latex
     if os.path.exists(filename):
-        return
+        return mathtext_parser.get_depth(latex, dpi=120)
     orig_fontset = rcParams['mathtext.fontset']
     rcParams['mathtext.fontset'] = fontset
     try:
-        mathtext_parser.to_png(filename, "$%s$" % latex, dpi=120)
+        depth = mathtext_parser.to_png(filename, latex, dpi=120)
     except:
-        warnings.warn("Could not render math expression $%s$" % latex,
-                      warnings.Warning)
+        warnings.warn("Could not render math expression %s" % latex,
+                      Warning)
+        depth = 0
     rcParams['mathtext.fontset'] = orig_fontset
+    return depth
 
 # LaTeX to HTML translation stuff:
 def latex2html(node, source):
@@ -131,8 +134,7 @@ def latex2html(node, source):
     print latex.encode("ascii", "backslashreplace")
     name = 'math-%s' % md5(latex).hexdigest()[-10:]
     dest = '_static/%s.png' % name
-    if not isfile(dest):
-        latex2png(latex, dest, node['fontset'])
+    depth = latex2png(latex, dest, node['fontset'])
 
     path = '_static'
     count = source.split('/doc/')[-1].count('/')
@@ -148,5 +150,10 @@ def latex2html(node, source):
         cls = ''
     else:
         cls = 'class="center" '
-    return '<img src="%s/%s.png" %s%s/>' % (path, name, align, cls)
+    if inline and depth != 0:
+        style = 'style="position: relative; bottom: -%dpx"' % (depth + 1)
+    else:
+        style = ''
+
+    return '<img src="%s/%s.png" %s%s%s/>' % (path, name, align, cls, style)
 
diff --git a/examples/user_interfaces/mathtext_wx.py b/examples/user_interfaces/mathtext_wx.py
@@ -21,7 +21,7 @@
 from matplotlib.mathtext import MathTextParser
 mathtext_parser = MathTextParser("Bitmap")
 def mathtext_to_wxbitmap(s):
-    ftimage = mathtext_parser.parse(s, 150)
+    ftimage, depth = mathtext_parser.parse(s, 150)
     return wx.BitmapFromBufferRGBA(
         ftimage.get_width(), ftimage.get_height(),
         ftimage.as_rgba_str())
diff --git a/lib/matplotlib/mathtext.py b/lib/matplotlib/mathtext.py
@@ -341,7 +341,7 @@ def MathtextBackendAgg():
 
 class MathtextBackendBitmapRender(MathtextBackendAggRender):
     def get_results(self, box):
-        return self.image
+        return self.image, self.depth
 
 def MathtextBackendBitmap():
     return MathtextBackendBbox(MathtextBackendBitmapRender())
@@ -2726,7 +2726,13 @@ def parse(self, s, dpi = 72, prop = None):
 
     def to_mask(self, texstr, dpi=120, fontsize=14):
         """
-        return an NxM uint8 alpha ubyte mask array of rasterized tex
+        Returns a tuple (*array*, *depth*)
+
+          - *array* is an NxM uint8 alpha ubyte mask array of
+            rasterized tex.
+
+          - depth is the offset of the baseline from the bottom of the
+            image in pixels.
 
         ''texstr''
             A valid mathtext string, eg r'IQ: $\sigma_i=15$'
@@ -2739,14 +2745,22 @@ def to_mask(self, texstr, dpi=120, fontsize=14):
         """
         assert(self._output=="bitmap")
         prop = FontProperties(size=fontsize)
-        ftimage = self.parse(texstr, dpi=dpi, prop=prop)
+        ftimage, depth = self.parse(texstr, dpi=dpi, prop=prop)
 
         x = ftimage.as_array()
-        return x
+        return x, depth
 
     def to_rgba(self, texstr, color='black', dpi=120, fontsize=14):
         """
-        return an NxMx4 RGBA array of ubyte rasterized tex
+        Returns a tuple (*array*, *depth*)
+
+          - *array* is an NxMx4 RGBA array of ubyte rasterized tex.
+
+          - depth is the offset of the baseline from the bottom of the
+            image in pixels.
+
+        Returns a tuple (array, depth), where depth is the offset of
+        the baseline from the bottom of the image.
 
         ''texstr''
             A valid mathtext string, eg r'IQ: $\sigma_i=15$'
@@ -2760,18 +2774,22 @@ def to_rgba(self, texstr, color='black', dpi=120, fontsize=14):
         ''fontsize''
             The font size in points
         """
-        x = self.to_mask(texstr, dpi=dpi, fontsize=fontsize)
+        x, depth = self.to_mask(texstr, dpi=dpi, fontsize=fontsize)
 
         r, g, b = mcolors.colorConverter.to_rgb(color)
         RGBA = np.zeros((x.shape[0], x.shape[1], 4), dtype=np.uint8)
         RGBA[:,:,0] = int(255*r)
         RGBA[:,:,1] = int(255*g)
         RGBA[:,:,2] = int(255*b)
         RGBA[:,:,3] = x
-        return RGBA
+        return RGBA, depth
 
     def to_png(self, filename, texstr, color='black', dpi=120, fontsize=14):
         """
+        Writes a tex expression to a PNG file.
+
+        Returns the offset of the baseline from the bottom of the
+        image in pixels.
 
         ''filename''
             A writable filename or fileobject
@@ -2790,7 +2808,27 @@ def to_png(self, filename, texstr, color='black', dpi=120, fontsize=14):
 
             """
 
-        rgba = self.to_rgba(texstr, color=color, dpi=dpi, fontsize=fontsize)
+        rgba, depth = self.to_rgba(texstr, color=color, dpi=dpi, fontsize=fontsize)
         numrows, numcols, tmp = rgba.shape
-        return _png.write_png(rgba.tostring(), numcols, numrows, filename)
+        _png.write_png(rgba.tostring(), numcols, numrows, filename)
+        return depth
+
+    def get_depth(self, texstr, dpi=120, fontsize=14):
+        """
+        Returns the offset of the baseline from the bottom of the
+        image in pixels.
+
+        ''texstr''
+            A valid mathtext string, eg r'IQ: $\sigma_i=15$'
+
+        ''dpi''
+            The dots-per-inch to render the text
+
+        ''fontsize''
+            The font size in points
 
+            """
+        assert(self._output=="bitmap")
+        prop = FontProperties(size=fontsize)
+        ftimage, depth = self.parse(texstr, dpi=dpi, prop=prop)
+        return depth
