Fix #7357: html: Resizing SVG image fails with ValueError

CHANGES

@@ -135,6 +135,7 @@ Bugs fixed
 * #5637: inheritance_diagram: Incorrect handling of nested class names
 * #7139: ``code-block:: guess`` does not work
 * #7325: html: source_suffix containing dot leads to wrong source link
+* #7357: html: Resizing SVG image fails with ValueError
 * #7278: html search: Fix use of ``html_file_suffix`` instead of
   ``html_link_suffix`` in search results
 * #7297: html theme: ``bizstyle`` does not support ``sidebarwidth``

sphinx/writers/html.py

@@ -11,6 +11,7 @@
 import copy
 import os
 import posixpath
+import re
 import warnings
 from typing import Any, Iterable, Tuple
 from typing import cast
@@ -38,6 +39,19 @@ logger = logging.getLogger(__name__)
 # http://www.arnebrodowski.de/blog/write-your-own-restructuredtext-writer.html
 
 
+def multiply_length(length: str, scale: int) -> str:
+    """Multiply *length* (width or height) by *scale*."""
+    matched = re.match(r'^(\d*\.?\d*)\s*(\S*)$', length)
+    if not matched:
+        return length
+    elif scale == 100:
+        return length
+    else:
+        amount, unit = matched.groups()
+        result = float(amount) * scale / 100
+        return "%s%s" % (int(result), unit)
+
+
 class HTMLWriter(Writer):
 
     # override embed-stylesheet default value to 0.
@@ -597,11 +611,10 @@ class HTMLTranslator(SphinxTranslator, BaseTranslator):
             if 'height' in node:
                 atts['height'] = node['height']
             if 'scale' in node:
-                scale = node['scale'] / 100.0
                 if 'width' in atts:
-                    atts['width'] = int(atts['width']) * scale
+                    atts['width'] = multiply_length(atts['width'], node['scale'])
                 if 'height' in atts:
-                    atts['height'] = int(atts['height']) * scale
+                    atts['height'] = multiply_length(atts['height'], node['scale'])
             atts['alt'] = node.get('alt', uri)
             if 'align' in node:
                 atts['class'] = 'align-%s' % node['align']

sphinx/writers/html5.py

@@ -10,6 +10,7 @@
 
 import os
 import posixpath
+import re
 import warnings
 from typing import Any, Iterable, Tuple
 from typing import cast
@@ -37,6 +38,19 @@ logger = logging.getLogger(__name__)
 # http://www.arnebrodowski.de/blog/write-your-own-restructuredtext-writer.html
 
 
+def multiply_length(length: str, scale: int) -> str:
+    """Multiply *length* (width or height) by *scale*."""
+    matched = re.match(r'^(\d*\.?\d*)\s*(\S*)$', length)
+    if not matched:
+        return length
+    elif scale == 100:
+        return length
+    else:
+        amount, unit = matched.groups()
+        result = float(amount) * scale / 100
+        return "%s%s" % (int(result), unit)
+
+
 class HTML5Translator(SphinxTranslator, BaseTranslator):
     """
     Our custom HTML translator.
@@ -538,11 +552,10 @@ class HTML5Translator(SphinxTranslator, BaseTranslator):
             if 'height' in node:
                 atts['height'] = node['height']
             if 'scale' in node:
-                scale = node['scale'] / 100.0
                 if 'width' in atts:
-                    atts['width'] = int(atts['width']) * scale
+                    atts['width'] = multiply_length(atts['width'], node['scale'])
                 if 'height' in atts:
-                    atts['height'] = int(atts['height']) * scale
+                    atts['height'] = multiply_length(atts['height'], node['scale'])
             atts['alt'] = node.get('alt', uri)
             if 'align' in node:
                 atts['class'] = 'align-%s' % node['align']