Added transform for visible links.

doc/builders.rst

@@ -71,6 +71,11 @@ The builder's "name" must be given to the **-b** command-line option of
    details about it.  For definition of the epub format, have a look at
    `<http://www.idpf.org/specs.htm>`_ or `<http://en.wikipedia.org/wiki/EPUB>`_.
 
+   Some ebook readers do not show the link targets of references.  Therefore
+   this builder adds the targets after the link when necessary.  The display
+   of the URLs can be customized by adding CSS rules for the class
+   ``link-target``.
+
    Its name is ``epub``.
 
 .. module:: sphinx.builders.latex

sphinx/builders/epub.py

@@ -16,6 +16,7 @@ from os import path
 import zipfile
 
 from docutils import nodes
+from docutils.transforms import Transform
 
 from sphinx.builders.html import StandaloneHTMLBuilder
 
@@ -111,6 +112,29 @@ _media_types = {
 }
 
 
+# The transform to show link targets
+
+class VisibleLinksTransform(Transform):
+    """
+    Add the link target of referances to the text, unless it is already
+    present in the description.
+    """
+
+    # This transform must run after the references transforms
+    default_priority = 680
+
+    def apply(self):
+        for ref in self.document.traverse(nodes.reference):
+            uri = ref.get('refuri', '')
+            if ( uri.startswith('http:') or uri.startswith('https:') or \
+                    uri.startswith('ftp:') ) and uri not in ref.astext():
+                uri = ' [%s]' % uri
+                idx = ref.parent.index(ref) + 1
+                link = nodes.inline(uri, uri)
+                link['classes'].append('link-target')
+                ref.parent.insert(idx, link)
+
+
 # The epub publisher
 
 class EpubBuilder(StandaloneHTMLBuilder):
@@ -137,6 +161,7 @@ class EpubBuilder(StandaloneHTMLBuilder):
         # the output files for epub must be .html only
         self.out_suffix = '.html'
         self.playorder = 0
+        self.app.add_transform(VisibleLinksTransform)
 
     def get_theme_config(self):
         return self.config.epub_theme, {}

sphinx/themes/epub/static/epub.css

@@ -420,6 +420,19 @@ div.footer a {
     text-decoration: underline;
 }
 
+/* -- link-target ----------------------------------------------------------- */
+
+.link-target {
+    font-size: 80%;
+}
+
+table .link-target {
+    /* Do not show links in tables, there is not enough space */
+    display: none;
+}
+
+/* -- font-face ------------------------------------------------------------- */
+
 @font-face {
     font-family: "LiberationNarrow";
     font-style: normal;