Fix #6696: html: scale option of image/figure directive not working for SVG

Note: imagesize-1.2.0 or above is required

3 files changed, 44 insertions, 28 deletions

diff --git a/CHANGES b/CHANGES
index fa0b2a2b1..d4e242057 100644
--- a/CHANGES
+++ b/CHANGES
@@ -30,6 +30,8 @@ Features added
   down the build
 * #6837: LaTeX: Support a nested table
 * #6966: graphviz: Support ``:class:`` option
+* #6696: html: ``:scale:`` option of image/figure directive not working for SVG
+  images (imagesize-1.2.0 or above is required)
 
 Bugs fixed
 ----------
diff --git a/sphinx/writers/html.py b/sphinx/writers/html.py
index 47c3fdb4a..84cdcc15b 100644
--- a/sphinx/writers/html.py
+++ b/sphinx/writers/html.py
@@ -579,6 +579,21 @@ class HTMLTranslator(SphinxTranslator, BaseTranslator):
             node['uri'] = posixpath.join(self.builder.imgpath,
                                          self.builder.images[olduri])
 
+        if 'scale' in node:
+            # Try to figure out image height and width.  Docutils does that too,
+            # but it tries the final file name, which does not necessarily exist
+            # yet at the time the HTML file is written.
+            if not ('width' in node and 'height' in node):
+                size = get_image_size(os.path.join(self.builder.srcdir, olduri))
+                if size is None:
+                    logger.warning(__('Could not obtain image size. :scale: option is ignored.'),  # NOQA
+                                   location=node)
+                else:
+                    if 'width' not in node:
+                        node['width'] = str(size[0])
+                    if 'height' not in node:
+                        node['height'] = str(size[1])
+
         uri = node['uri']
         if uri.lower().endswith(('svg', 'svgz')):
             atts = {'src': uri}
@@ -586,6 +601,12 @@ class HTMLTranslator(SphinxTranslator, BaseTranslator):
                 atts['width'] = node['width']
             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
+                if 'height' in atts:
+                    atts['height'] = int(atts['height']) * scale
             atts['alt'] = node.get('alt', uri)
             if 'align' in node:
                 self.body.append('<div align="%s" class="align-%s">' %
@@ -596,20 +617,6 @@ class HTMLTranslator(SphinxTranslator, BaseTranslator):
             self.body.append(self.emptytag(node, 'img', '', **atts))
             return
 
-        if 'scale' in node:
-            # Try to figure out image height and width.  Docutils does that too,
-            # but it tries the final file name, which does not necessarily exist
-            # yet at the time the HTML file is written.
-            if not ('width' in node and 'height' in node):
-                size = get_image_size(os.path.join(self.builder.srcdir, olduri))
-                if size is None:
-                    logger.warning(__('Could not obtain image size. :scale: option is ignored.'),  # NOQA
-                                   location=node)
-                else:
-                    if 'width' not in node:
-                        node['width'] = str(size[0])
-                    if 'height' not in node:
-                        node['height'] = str(size[1])
         super().visit_image(node)
 
     # overwritten
diff --git a/sphinx/writers/html5.py b/sphinx/writers/html5.py
index aebe1e428..087c92842 100644
--- a/sphinx/writers/html5.py
+++ b/sphinx/writers/html5.py
@@ -520,6 +520,21 @@ class HTML5Translator(SphinxTranslator, BaseTranslator):
             node['uri'] = posixpath.join(self.builder.imgpath,
                                          self.builder.images[olduri])
 
+        if 'scale' in node:
+            # Try to figure out image height and width.  Docutils does that too,
+            # but it tries the final file name, which does not necessarily exist
+            # yet at the time the HTML file is written.
+            if not ('width' in node and 'height' in node):
+                size = get_image_size(os.path.join(self.builder.srcdir, olduri))
+                if size is None:
+                    logger.warning(__('Could not obtain image size. :scale: option is ignored.'),  # NOQA
+                                   location=node)
+                else:
+                    if 'width' not in node:
+                        node['width'] = str(size[0])
+                    if 'height' not in node:
+                        node['height'] = str(size[1])
+
         uri = node['uri']
         if uri.lower().endswith(('svg', 'svgz')):
             atts = {'src': uri}
@@ -527,6 +542,12 @@ class HTML5Translator(SphinxTranslator, BaseTranslator):
                 atts['width'] = node['width']
             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
+                if 'height' in atts:
+                    atts['height'] = int(atts['height']) * scale
             atts['alt'] = node.get('alt', uri)
             if 'align' in node:
                 self.body.append('<div align="%s" class="align-%s">' %
@@ -537,20 +558,6 @@ class HTML5Translator(SphinxTranslator, BaseTranslator):
             self.body.append(self.emptytag(node, 'img', '', **atts))
             return
 
-        if 'scale' in node:
-            # Try to figure out image height and width.  Docutils does that too,
-            # but it tries the final file name, which does not necessarily exist
-            # yet at the time the HTML file is written.
-            if not ('width' in node and 'height' in node):
-                size = get_image_size(os.path.join(self.builder.srcdir, olduri))
-                if size is None:
-                    logger.warning(__('Could not obtain image size. :scale: option is ignored.'),  # NOQA
-                                   location=node)
-                else:
-                    if 'width' not in node:
-                        node['width'] = str(size[0])
-                    if 'height' not in node:
-                        node['height'] = str(size[1])
         super().visit_image(node)
 
     # overwritten