Viewer: Fix search history not persisting between viewer restarts. Fixes #1847976 [feature request: viewer 4 search history as in viewer 3](https://bugs.launchpad.net/calibre/+bug/1847976)

src/calibre/gui2/viewer/web_view.py

@@ -43,6 +43,7 @@ except ImportError:
 vprefs = JSONConfig('viewer-webengine')
 viewer_config_dir = os.path.join(config_dir, 'viewer')
 vprefs.defaults['session_data'] = {}
+vprefs.defaults['local_storage'] = {}
 vprefs.defaults['main_window_state'] = None
 vprefs.defaults['main_window_geometry'] = None
 vprefs.defaults['old_prefs_migrated'] = False
@@ -223,6 +224,7 @@ def create_profile():
 class ViewerBridge(Bridge):
 
     set_session_data = from_js(object, object)
+    set_local_storage = from_js(object, object)
     reload_book = from_js()
     toggle_toc = from_js()
     toggle_bookmarks = from_js()
@@ -399,6 +401,7 @@ class WebView(RestartingWebEngineView):
         self._page = WebPage(self)
         self.bridge.bridge_ready.connect(self.on_bridge_ready)
         self.bridge.set_session_data.connect(self.set_session_data)
+        self.bridge.set_local_storage.connect(self.set_local_storage)
         self.bridge.reload_book.connect(self.reload_book)
         self.bridge.toggle_toc.connect(self.toggle_toc)
         self.bridge.toggle_bookmarks.connect(self.toggle_bookmarks)
@@ -482,7 +485,7 @@ class WebView(RestartingWebEngineView):
         f = QApplication.instance().font()
         fi = QFontInfo(f)
         self.bridge.create_view(
-            vprefs['session_data'], QFontDatabase().families(), field_metadata.all_metadata(),
+            vprefs['session_data'], vprefs['local_storage'], QFontDatabase().families(), field_metadata.all_metadata(),
             f.family(), '{}px'.format(fi.pixelSize()), self.show_home_page_on_ready)
         for func, args in iteritems(self.pending_bridge_ready_actions):
             getattr(self.bridge, func)(*args)
@@ -517,6 +520,14 @@ class WebView(RestartingWebEngineView):
             if key in ('standalone_font_settings', 'base_font_size'):
                 apply_font_settings(self._page)
 
+    def set_local_storage(self, key, val):
+        if key == '*' and val is None:
+            vprefs['local_storage'] = {}
+        elif key != '*':
+            sd = vprefs['local_storage']
+            sd[key] = val
+            vprefs['local_storage'] = sd
+
     def do_callback(self, func_name, callback):
         cid = next(self.callback_id_counter)
         self.callback_map[cid] = callback

src/pyj/viewer-main.pyj

@@ -20,7 +20,7 @@ from read_book.globals import runtime, ui_operations
 from read_book.iframe import main as iframe_main
 from read_book.shortcuts import add_standalone_viewer_shortcuts
 from read_book.view import View
-from session import session_defaults
+from session import session_defaults, local_storage
 from utils import encode_query_with_path, parse_url_params
 from viewer.constants import FAKE_HOST, FAKE_PROTOCOL, READER_BACKGROUND_URL
 
@@ -183,20 +183,43 @@ class SessionData:
         to_python.set_session_data('*', None)
 
 
-def create_session_data(prefs):
+class LocalStorage:
+
+    def __init__(self, data):
+        self.data = data
+
+    def get(self, key, defval):
+        ans = self.data[key]
+        if ans is undefined or ans is None:
+            if defval is undefined:
+                defval = None
+            return defval
+        return ans
+
+    def set(self, key, val):
+        self.data[key] = val
+        to_python.set_local_storage(key, val)
+
+    def clear(self):
+        self.data = {}
+        to_python.set_local_storage('*', None)
+
+
+def create_session_data(prefs, local_storage_data):
     sd = SessionData(prefs)
     set_session_data(sd)
+    local_storage.storage = LocalStorage(local_storage_data)
 
 
 @from_python
-def create_view(prefs, all_font_families, field_metadata, ui_font_family, ui_font_sz, show_home_page_on_ready):
+def create_view(prefs, local_storage, all_font_families, field_metadata, ui_font_family, ui_font_sz, show_home_page_on_ready):
     nonlocal view
     runtime.all_font_families = all_font_families
     library_data.field_metadata = field_metadata
     document.documentElement.style.fontFamily = f'"{ui_font_family}", sans-serif'
     document.documentElement.style.fontSize = ui_font_sz
     if view is None:
-        create_session_data(prefs)
+        create_session_data(prefs, local_storage)
         view = View(document.getElementById('view'))
         if show_home_page_on_ready:
             view.overlay.open_book(False)