Regression: restore extraction of data-URI images from source for builders whose output formats do not support them natively (#12344)

Author: jayaddison

CHANGES.rst

@@ -73,6 +73,9 @@ Bugs fixed
 * #12459: Add valid-type arguments to the ``linkcheck_rate_limit_timeout``
   configuration setting.
   Patch by James Addison.
+* #12331: Resolve data-URI-image-extraction regression from v7.3.0 affecting
+  builders without native support for data-URIs in their output format.
+  Patch by James Addison.
 
 Improvements
 ------------

sphinx/builders/__init__.py

@@ -71,9 +71,9 @@ class Builder:
     #: The list of MIME types of image formats supported by the builder.
     #: Image files are searched in the order in which they appear here.
     supported_image_types: list[str] = []
-    #: The builder supports remote images or not.
+    #: The builder can produce output documents that may fetch external images when opened.
     supported_remote_images = False
-    #: The builder supports data URIs or not.
+    #: The file format produced by the builder allows images to be embedded using data-URIs.
     supported_data_uri_images = False
 
     def __init__(self, app: Sphinx, env: BuildEnvironment) -> None:

sphinx/transforms/post_transforms/images.py

@@ -115,10 +115,8 @@ class DataURIExtractor(BaseImageConverter):
     default_priority = 150
 
     def match(self, node: nodes.image) -> bool:
-        if not self.app.builder.supported_remote_images:
-            return False
         if self.app.builder.supported_data_uri_images is True:
-            return False
+            return False  # do not transform the image; data URIs are valid in the build output
         return node['uri'].startswith('data:')
 
     def handle(self, node: nodes.image) -> None:

tests/roots/test-images/index.rst

@@ -27,3 +27,8 @@ test-image
 
 .. non-exist remote image
 .. image:: http://localhost:7777/NOT_EXIST.PNG
+
+.. a self-contained image within a data URI
+   This image was generated using ImageMagick 6.9 with the command ``convert -pointsize 32 -font Noto-Sans-Egyptian-Hieroglyphs-Regular caption:$(printf '\U13080') -trim -border 2 -monochrome eoh.png``
+.. image:: data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACoAAAAjAQAAAADKt6U+AAAAAmJLR0QAAd2KE6QAAAAHdElNRQfoBQIVBgOBlOMTAAAAEGNhTnYAAAAtAAAAOwAAAAEAAAATst46RgAAAJtJREFUCNdNz70KwkAMAOA8iOhjuGh9HB9BCtoTHHwMH0Mc7KWTmx0dHDpovUk6HCil3sUmATHLR/4IAeJA+LEWPmbEeHJMWbTMZDA0CNFn8x1COFPaIHQ55R7hlZGdIjwj2aovRjJbhPvMLNN+r0g2vB7ByIWbHqqVh3LR3lhZWM0qYV8qjU6+lc4J7ZVx4SjEINBKOSinv/+YL1xvsJE6ztdqAAAADHRFWHRjYXB0aW9uAPCTgoD4hdKUAAAAD3RFWHRjYXB0aW9uOmxpbmVzADGoBz2RAAAAAElFTkSuQmCC
+   :alt: The Eye of Horus in a black font on a white background.

tests/test_builders/test_build_epub.py

@@ -409,6 +409,7 @@ def test_copy_images(app, status, warning):
     images = {image.name for image in images_dir.rglob('*')}
     images.discard('python-logo.png')
     assert images == {
+        # 'ba30773957c3fe046897111afd65a80b81cad089.png',  # epub: image from data:image/png URI in source
         'img.png',
         'rimg.png',
         'rimg1.png',

tests/test_builders/test_build_html_image.py

@@ -72,6 +72,7 @@ def test_copy_images(app, status, warning):
     images_dir = Path(app.outdir) / '_images'
     images = {image.name for image in images_dir.rglob('*')}
     assert images == {
+        # 'ba30773957c3fe046897111afd65a80b81cad089.png',  # html: image from data:image/png URI in source
         'img.png',
         'rimg.png',
         'rimg1.png',

tests/test_builders/test_build_latex.py

@@ -1711,6 +1711,7 @@ def test_copy_images(app, status, warning):
     }
     images.discard('sphinx.png')
     assert images == {
+        'ba30773957c3fe046897111afd65a80b81cad089.png',  # latex: image from data:image/png URI in source
         'img.pdf',
         'rimg.png',
         'testimäge.png',

tests/test_builders/test_build_texinfo.py

@@ -124,6 +124,7 @@ def test_copy_images(app, status, warning):
     images = {image.name for image in images_dir.rglob('*')}
     images.discard('python-logo.png')
     assert images == {
+        'ba30773957c3fe046897111afd65a80b81cad089.png',  # texinfo: image from data:image/png URI in source
         'img.png',
         'rimg.png',
         'testimäge.png',