Preview panel: Allow syncing of position more accurately when there are multiple tags on the same source code line

src/calibre/ebooks/oeb/polish/preview.coffee

@@ -226,6 +226,11 @@ get_matched_css = (node, is_ancestor, all_properties) ->
 
     return ans.reverse()
 
+scroll_to_node = (node) ->
+    if node is document.body
+        window.scrollTo(0, 0)
+    else
+        node.scrollIntoView()
 
 class PreviewIntegration
 
@@ -244,11 +249,15 @@ class PreviewIntegration
         for node in document.querySelectorAll('[data-lnum="' + lnum + '"]')
             if is_hidden(node)
                 continue
-            if node is document.body
-                window.scrollTo(0, 0)
-            else
-                node.scrollIntoView()
-            return
+            scroll_to_node(node)
+
+    go_to_sourceline_address: (sourceline, tags) =>
+        for node, index in document.querySelectorAll('[data-lnum="' + sourceline + '"]')
+            if index >= tags.length or node.tagName.toLowerCase() != tags[index]
+                break
+            if index == tags.length - 1 and not is_hidden(node)
+                return scroll_to_node(node)
+        this.go_to_line(sourceline)
 
     line_numbers: () =>
         found_body = false
@@ -300,14 +309,14 @@ class PreviewIntegration
             this.report_split(event.target)
         else
             e = event.target
+            address = get_sourceline_address(e)
             # Find the closest containing link, if any
-            lnum = e.getAttribute('data-lnum')
             href = tn = ''
             while e and e != document.body and e != document and (tn != 'a' or not href)
                 tn = e.tagName?.toLowerCase()
                 href = e.getAttribute('href')
                 e = e.parentNode
-            window.py_bridge.request_sync(tn, href, lnum)
+            window.py_bridge.request_sync(tn, href, JSON.stringify(address))
         return false
 
     go_to_anchor: (anchor, lnum) =>

src/calibre/gui2/tweak_book/boss.py

@@ -1014,11 +1014,11 @@ class Boss(QObject):
         mt = current_container().mime_map.get(name, guess_type(name))
         self.edit_file_requested(name, None, mt)
 
-    def sync_editor_to_preview(self, name, lnum):
+    def sync_editor_to_preview(self, name, sourceline_address):
         editor = self.edit_file(name, 'html')
         self.ignore_preview_to_editor_sync = True
         try:
-            editor.current_line = lnum
+            editor.goto_sourceline(*sourceline_address)
         finally:
             self.ignore_preview_to_editor_sync = False
 
@@ -1029,7 +1029,7 @@ class Boss(QObject):
         if ed is not None:
             name = editor_name(ed)
             if name is not None and getattr(ed, 'syntax', None) == 'html':
-                self.gui.preview.sync_to_editor(name, ed.current_line)
+                self.gui.preview.sync_to_editor(name, ed.current_tag())
 
     def sync_live_css_to_editor(self):
         ed = self.gui.central.current_editor

src/calibre/gui2/tweak_book/preview.py

@@ -330,9 +330,9 @@ class WebPage(QWebPage):
         mf.evaluateJavaScript(self.js)
 
     @pyqtSlot(str, str, str)
-    def request_sync(self, tag_name, href, lnum):
+    def request_sync(self, tag_name, href, sourceline_address):
         try:
-            self.sync_requested.emit(unicode(tag_name), unicode(href), int(unicode(lnum)))
+            self.sync_requested.emit(unicode(tag_name), unicode(href), json.loads(unicode(sourceline_address)))
         except (TypeError, ValueError, OverflowError, AttributeError):
             pass
 
@@ -369,6 +369,14 @@ class WebPage(QWebPage):
         self.mainFrame().evaluateJavaScript(
             'window.calibre_preview_integration.go_to_line(%d)' % lnum)
 
+    def go_to_sourceline_address(self, sourceline_address):
+        lnum, tags = sourceline_address
+        if lnum is None:
+            return
+        tags = [x.lower() for x in tags]
+        self.mainFrame().evaluateJavaScript(
+            'window.calibre_preview_integration.go_to_sourceline_address(%d, %s)' % (lnum, json.dumps(tags)))
+
     def split_mode(self, enabled):
         self.mainFrame().evaluateJavaScript(
             'window.calibre_preview_integration.split_mode(%s)' % (
@@ -538,8 +546,8 @@ class Preview(QWidget):
         if self.current_name:
             self.split_requested.emit(self.current_name, loc, totals)
 
-    def sync_to_editor(self, name, lnum):
-        self.current_sync_request = (name, lnum)
+    def sync_to_editor(self, name, sourceline_address):
+        self.current_sync_request = (name, sourceline_address)
         QTimer.singleShot(100, self._sync_to_editor)
 
     def _sync_to_editor(self):
@@ -550,9 +558,9 @@ class Preview(QWidget):
                 return QTimer.singleShot(100, self._sync_to_editor)
         except TypeError:
             return  # Happens if current_sync_request is None
-        lnum = self.current_sync_request[1]
+        sourceline_address = self.current_sync_request[1]
         self.current_sync_request = None
-        self.view.page().go_to_line(lnum)
+        self.view.page().go_to_sourceline_address(sourceline_address)
 
     def show(self, name):
         if name != self.current_name: