Start work on popup footnote support in the browser viewer

src/calibre/srv/render_book.py

@@ -201,6 +201,7 @@ class Container(ContainerBase):
             'spine_length': 0,
             'toc_anchor_map': toc_anchor_map(toc),
             'landmarks': landmarks,
+            'link_to_map': {},
         }
         # Mark the spine as dirty since we have to ensure it is normalized
         for name in data['spine']:
@@ -328,6 +329,8 @@ class Container(ContainerBase):
                 changed.add(base)
             return url
 
+        ltm = self.book_render_data['link_to_map']
+
         for name, mt in self.mime_map.iteritems():
             mt = mt.lower()
             if mt in OEB_STYLES:
@@ -350,7 +353,9 @@ class Container(ContainerBase):
                     if href.startswith(link_uid):
                         a.set('href', 'javascript:void(0)')
                         parts = decode_url(href.split('|')[1])
-                        a.set('data-' + link_uid, json.dumps({'name':parts[0], 'frag':parts[1]}, ensure_ascii=False))
+                        lname, lfrag = parts[0], parts[1]
+                        ltm.setdefault(lname, {}).setdefault(lfrag or '', []).append(name)
+                        a.set('data-' + link_uid, json.dumps({'name':lname, 'frag':lfrag}, ensure_ascii=False))
                     else:
                         a.set('target', '_blank')
                         a.set('rel', 'noopener noreferrer')
@@ -382,7 +387,7 @@ boolean_attributes = frozenset('allowfullscreen,async,autofocus,autoplay,checked
 
 EPUB_TYPE_MAP = {k:'doc-' + k for k in (
     'abstract acknowledgements afterword appendix biblioentry bibliography biblioref chapter colophon conclusion cover credit'
-    ' credits dedication epigraph epilogue errata footnote footnotes forward glossary glossref index introduction noteref notice'
+    ' credits dedication epigraph epilogue errata footnote footnotes forward glossary glossref index introduction link noteref notice'
     ' pagebreak pagelist part preface prologue pullquote qna locator subtitle title toc').split(' ')}
 for k in 'figure term definition directory list list-item table row cell'.split(' '):
     EPUB_TYPE_MAP[k] = k

src/pyj/read_book/footnotes.pyj

@@ -0,0 +1,70 @@
+# vim:fileencoding=utf-8
+# License: GPL v3 Copyright: 2017, Kovid Goyal <kovid at kovidgoyal.net>
+from __python__ import bound_methods, hash_literals
+
+
+def elem_roles(elem):
+    return {k.toLowerCase(): True for k in (elem.getAttribute('role') or '').split(' ')}
+
+
+def get_containing_block(node):
+    while node and node.tagName and get_containing_block.block_names[node.tagName.toLowerCase()] is not True:
+        node = node.parentNode
+    return node
+get_containing_block.block_names = dict.fromkeys(v"['p', 'div', 'li', 'td', 'h1', 'h2', 'h2', 'h3', 'h4', 'h5', 'h6', 'body']", True).as_object()
+
+
+def is_footnote_link(a, dest_name, dest_frag, src_name, link_to_map):
+    roles = elem_roles(a)
+    if roles['doc-noteref']:
+        return True
+    if roles['doc-link']:
+        return False
+
+    # Check if node or any of its first few parents have vertical-align set
+    x, num = a, 3
+    while x and num > 0:
+        style = window.getComputedStyle(x)
+        if not is_footnote_link.inline_displays[style.display]:
+            break
+        if is_footnote_link.vert_aligns[style.verticalAlign]:
+            return True
+        x = x.parentNode
+        num -= 1
+
+    # Check if node has a single child with the appropriate css
+    children = [x for x in a.childNodes if x.nodeType is Node.ELEMENT_NODE]
+    if children.length == 1:
+        style = window.getComputedStyle(children[0])
+        if is_footnote_link.inline_displays[style.display] and is_footnote_link.vert_aligns[style.verticalAlign]:
+            text_children = [x for x in a.childNodes if x.nodeType is Node.TEXT_NODE and x.nodeValue and /\S+/.test(x.nodeValue)]
+            if not text_children.length:
+                return True
+
+    eid = a.getAttribute('id') or a.getAttribute('name')
+    files_linking_to_self = link_to_map[src_name]
+    if eid and files_linking_to_self:
+        files_linking_to_anchor = files_linking_to_self[eid]
+        if files_linking_to_anchor.length > 1 or (files_linking_to_anchor.length == 1 and files_linking_to_anchor[0] is not src_name):
+            # An <a href="..." id="..."> link that is linked back from some other
+            # file in the spine, most likely an endnote. We exclude links that are
+            # the only content of their parent block tag, as these are not likely
+            # to be endnotes.
+            cb = get_containing_block(a)
+            if not cb or cb.tagName.toLowerCase() == 'body':
+                return False
+            ltext = a.textContent
+            if not ltext:
+                return False
+            ctext = cb.textContent
+            if not ctext:
+                return False
+            if ctext.strip() is ltext.strip():
+                return False
+            return True
+
+    return False
+
+
+is_footnote_link.inline_displays = {'inline': True, 'inline-block': True}
+is_footnote_link.vert_aligns = {'sub': True, 'super': True, 'top': True, 'bottom': True}

src/pyj/read_book/iframe.pyj

@@ -12,6 +12,7 @@ from read_book.flow_mode import (
     flow_to_scroll_fraction, handle_gesture as flow_handle_gesture,
     layout as flow_layout, scroll_by_page as flow_scroll_by_page
 )
+from read_book.footnotes import is_footnote_link
 from read_book.globals import (
     current_book, current_layout_mode, current_spine_item, set_boss,
     set_current_spine_item, set_layout_mode
@@ -383,6 +384,14 @@ class IframeBoss:
         name, frag = data.name, data.frag
         if not name:
             name = current_spine_item().name
+        try:
+            is_popup = is_footnote_link(evt.currentTarget, name, frag, current_spine_item().name, self.book.manifest.link_to_map or {})
+        except:
+            import traceback
+            traceback.print_exc()
+            is_popup = False
+        if is_popup:
+            pass
         if name is current_spine_item().name:
             self.replace_history_on_next_cfi_update = False
             self.scroll_to_anchor(frag)