E-book viewer: Show the URL when hovering over external links. Fixes #1911107 [Enhancement Request: ebook-viewer: Preview link destination](https://bugs.launchpad.net/calibre/+bug/1911107)

src/calibre/gui2/viewer/web_view.py

@@ -496,6 +496,7 @@ class WebView(RestartingWebEngineView):
         self.show_home_page_on_ready = True
         self._size_hint = QSize(int(w/3), int(w/2))
         self._page = WebPage(self)
+        self._page.linkHovered.connect(self.link_hovered)
         self.view_is_ready = False
         self.bridge.bridge_ready.connect(self.on_bridge_ready)
         self.bridge.view_created.connect(self.on_view_created)
@@ -549,6 +550,11 @@ class WebView(RestartingWebEngineView):
             self.inspector = Inspector(parent.inspector_dock.toggleViewAction(), self)
             parent.inspector_dock.setWidget(self.inspector)
 
+    def link_hovered(self, url):
+        if url == 'javascript:void(0)':
+            url = ''
+        self.generic_action('show-status-message', {'text': url})
+
     def shutdown(self):
         self.tts.shutdown()
 

src/pyj/read_book/prefs/head_foot.pyj

@@ -165,13 +165,15 @@ def format_pos(progress_frac, length):
     return f'{pos:.1f} / {pages}'
 
 
-def render_head_foot(div, which, region, metadata, current_toc_node, current_toc_toplevel_node, book_time, chapter_time, pos):
+def render_head_foot(div, which, region, metadata, current_toc_node, current_toc_toplevel_node, book_time, chapter_time, pos, override):
     template = get_session_data().get(which) or {}
     field = template[region] or 'empty'
     interface_data = get_interface_data()
     text = ''
     has_clock = False
-    if field is 'progress':
+    if override:
+        text = override
+    elif field is 'progress':
         percent = min(100, max(Math.round(pos.progress_frac * 100), 0))
         text = percent + '%'
     elif field is 'title':

src/pyj/read_book/view.pyj

@@ -209,6 +209,7 @@ class View:
         self.loaded_resources = {}
         self.current_progress_frac = self.current_file_progress_frac = 0
         self.current_page_counts = {'current': 0, 'total': 0, 'pages_per_screen': 1}
+        self.current_status_message = ''
         self.current_toc_node = self.current_toc_toplevel_node = None
         self.current_toc_families = v'[]'
         self.report_cfi_callbacks = {}
@@ -1244,26 +1245,35 @@ class View:
         }
         return pos
 
+    def show_status_message(self, msg):
+        self.current_status_message = msg or ''
+        self.update_header_footer()
+        if self.current_status_message:
+            window.setTimeout(def(): self.show_status_message();, 10000)
+
     def update_header_footer(self):
         sd = get_session_data()
         has_clock = False
         pos = self.current_position_data
+        if not self.book:
+            return
 
         book_length = pos.book_length * max(0, 1 - pos.progress_frac)
         chapter_length =  pos.chapter_length * max(0, 1 - pos.file_progress_frac)
         book_time = self.timers.time_for(book_length)
         chapter_time = self.timers.time_for(chapter_length)
 
-        def render_template(div, sz_attr, name):
+        def render_template(div, edge, name):
             nonlocal has_clock
             c = div.lastChild
             b = c.previousSibling
             a = b.previousSibling
-            if sd.get(sz_attr, 20) > 5:
+            if sd.get(f'margin_{edge}', 20) > 5:
                 mi = self.book.metadata
-                hca = render_head_foot(a, name, 'left', mi, self.current_toc_node, self.current_toc_toplevel_node, book_time, chapter_time, pos)
-                hcb = render_head_foot(b, name, 'middle', mi, self.current_toc_node, self.current_toc_toplevel_node, book_time, chapter_time, pos)
-                hcc = render_head_foot(c, name, 'right', mi, self.current_toc_node, self.current_toc_toplevel_node, book_time, chapter_time, pos)
+                override = self.current_status_message if edge is 'bottom' else ''
+                hca = render_head_foot(a, name, 'left', mi, self.current_toc_node, self.current_toc_toplevel_node, book_time, chapter_time, pos, override)
+                hcb = render_head_foot(b, name, 'middle', mi, self.current_toc_node, self.current_toc_toplevel_node, book_time, chapter_time, pos, '')
+                hcc = render_head_foot(c, name, 'right', mi, self.current_toc_node, self.current_toc_toplevel_node, book_time, chapter_time, pos, '')
                 if hca or hcb or hcc:
                     has_clock = True
             else:
@@ -1273,7 +1283,7 @@ class View:
             div = document.getElementById(f'book-{edge}-margin')
             if div:
                 tname = {'left':'left-margin', 'right': 'right-margin', 'top': 'header', 'bottom': 'footer'}[edge]
-                render_template(div, f'margin_{edge}', tname)
+                render_template(div, edge, tname)
         if has_clock:
             if not self.timer_ids.clock:
                 self.timer_ids.clock = window.setInterval(self.update_header_footer, 60000)
@@ -1310,6 +1320,7 @@ class View:
         # We cannot encrypt this message because the resource data contains
         # Blob objects which do not survive encryption
         self.processing_spine_item_display = True
+        self.current_status_message = ''
         self.iframe.style.visibility = 'hidden'
         self.iframe_wrapper.send_unencrypted_message('display',
             resource_data=resource_data, book=self.book, name=self.currently_showing.name,

src/pyj/viewer-main.pyj

@@ -207,6 +207,8 @@ def highlight_action(uuid, which):
 def generic_action(which, data):
     if which is 'set-notes-in-highlight':
         view.set_notes_for_highlight(data.uuid, data.notes or '')
+    if which is 'show-status-message':
+        view.show_status_message(data.text)
 
 
 @from_python