Recognize footnote links

src/calibre/ebooks/oeb/display/extract.coffee

@@ -29,6 +29,38 @@ inline_styles = (node) ->
 
     return cnode
 
+is_footnote_link = (node, url) ->
+    if not url or url.substr(0, 'file://'.length).toLowerCase() != 'file://'
+        return false  # Ignore non-local links
+    # Check for epub:type="noteref", a little complex as we dont operate in XML
+    # mode
+    epub_type = node.getAttributeNS("http://www.idpf.org/2007/ops", 'type') or node.getAttribute('epub:type')
+    if not epub_type
+        for x in node.attributes  # consider any xxx:type="noteref" attribute as marking a note
+            if x.nodeName and x.nodeValue == 'noteref' and x.nodeName.slice(-':type'.length) == ':type'
+                epub_type = 'noteref'
+                break
+    if epub_type and epub_type.toLowerCase() == 'noteref'
+        return true
+
+    # Check if node or any of its first few parents have vertical-align set
+    [x, num] = [node, 3]
+    while x and num > 0
+        style = window.getComputedStyle(x)
+        if style.verticalAlign in ['sub', 'super']
+            return true
+        x = x.parentNode
+        num -= 1
+
+    # Check if node has a single child with the appropriate css
+    children = (x for x in node.childNodes when x.nodeType == Node.ELEMENT_NODE)
+    if children.length == 1
+        style = window.getComputedStyle(children[0])
+        if style.verticalAlign in ['sub', 'super']
+            return true
+
+    return false
+
 class CalibreExtract
     # This class is a namespace to expose functions via the
     # window.calibre_extract object.
@@ -47,6 +79,15 @@ class CalibreExtract
         cnode = inline_styles(node)
         return cnode.outerHTML
 
+    get_footnote_data: () =>
+        ans = {}
+        for a in document.querySelectorAll('a[href]')
+            url = a.href  # .href returns the full URL while getAttribute() returns the value of the attribute
+            if not is_footnote_link(a, url)
+                continue
+            ans[url] = 1
+        return JSON.stringify(ans)
+
 if window?
     window.calibre_extract = new CalibreExtract()
 

src/calibre/gui2/viewer/documentview.py

@@ -27,6 +27,7 @@ from calibre.gui2.viewer.image_popup import ImagePopup
 from calibre.gui2.viewer.table_popup import TablePopup
 from calibre.gui2.viewer.inspector import WebInspector
 from calibre.gui2.viewer.gestures import GestureHandler
+from calibre.gui2.viewer.footnote import Footnotes
 from calibre.ebooks.oeb.display.webview import load_html
 from calibre.constants import isxp, iswindows, DEBUG
 # }}}
@@ -507,6 +508,7 @@ class DocumentView(QWebView):  # {{{
         self.to_bottom = False
         self.document = Document(self.shortcuts, parent=self,
                 debug_javascript=debug_javascript)
+        self.footnotes = Footnotes(self.document)
         self.setPage(self.document)
         self.inspector = WebInspector(self, self.document)
         self.manager = None
@@ -1306,6 +1308,12 @@ class DocumentView(QWebView):  # {{{
         return QWebView.event(self, ev)
 
     def mouseReleaseEvent(self, ev):
+        url = self.document.mainFrame().hitTestContent(ev.pos()).linkUrl()
+        if url.isValid():
+            fd = self.footnotes.get_footnote_data(url)
+            if fd is not None:
+                print (fd)
+        return
         opos = self.document.ypos
         if self.manager is not None:
             prev_pos = self.manager.update_page_number()

src/calibre/gui2/viewer/footnote.py

@@ -6,11 +6,30 @@ from __future__ import (unicode_literals, division, absolute_import,
 __license__ = 'GPL v3'
 __copyright__ = '2014, Kovid Goyal <kovid at kovidgoyal.net>'
 
+import json
+
+from PyQt4.Qt import QUrl
+
 class Footnotes(object):
 
-    def __init__(self):
+    def __init__(self, document):
+        self.document = document
         self.clear()
 
     def clear(self):
-        self.url_cache = {}
+        self.footnote_data_cache = {}
+
+    def get_footnote_data(self, url):
+        current_url = unicode(self.document.mainFrame().baseUrl().toLocalFile())
+        if not current_url:
+            return  # Not viewing a local file
+        fd = self.footnote_data_cache.get(current_url, None)
+        if fd is None:
+            raw = self.document.javascript('window.calibre_extract.get_footnote_data()', typ='string')
+            try:
+                fd = frozenset(unicode(QUrl(x).toLocalFile()) for x in json.loads(raw))
+            except Exception:
+                fd = frozenset()
+            self.footnote_data_cache[current_url] = fd
+