Viewer: Search panel: Add a button to return to the position the book was at before doing a search. Fixes #1879889 [[Enhancement - Viewer] Go back to last reading position after going through search results](https://bugs.launchpad.net/calibre/+bug/1879889)

src/calibre/gui2/viewer/search.py

@@ -315,6 +315,7 @@ class SearchInput(QWidget):  # {{{
 
     do_search = pyqtSignal(object)
     cleared = pyqtSignal()
+    go_back = pyqtSignal()
 
     def __init__(self, parent=None, panel_name='search'):
         QWidget.__init__(self, parent)
@@ -376,6 +377,12 @@ class SearchInput(QWidget):  # {{{
         cs.stateChanged.connect(self.save_search_type)
         h.addWidget(cs)
 
+        self.return_button = rb = QToolButton(self)
+        rb.setIcon(QIcon(I('back.png')))
+        rb.setToolTip(_('Go back to where you were before searching'))
+        rb.clicked.connect(self.go_back)
+        h.addWidget(rb)
+
     def history_saved(self, new_text, history):
         if new_text:
             sss = vprefs.get('saved-{}-settings'.format(self.panel_name)) or {}
@@ -646,11 +653,13 @@ class SearchPanel(QWidget):  # {{{
     show_search_result = pyqtSignal(object)
     count_changed = pyqtSignal(object)
     hide_search_panel = pyqtSignal()
+    goto_cfi = pyqtSignal(object)
 
     def __init__(self, parent=None):
         QWidget.__init__(self, parent)
         self.last_hidden_text_warning = None
         self.current_search = None
+        self.anchor_cfi = None
         self.l = l = QVBoxLayout(self)
         l.setContentsMargins(0, 0, 0, 0)
         self.search_input = si = SearchInput(self)
@@ -659,6 +668,7 @@ class SearchPanel(QWidget):  # {{{
         self.results_found.connect(self.on_result_found, type=Qt.QueuedConnection)
         si.do_search.connect(self.search_requested)
         si.cleared.connect(self.search_cleared)
+        si.go_back.connect(self.go_back)
         l.addWidget(si)
         self.results = r = Results(self)
         r.count_changed.connect(self.count_changed)
@@ -674,6 +684,10 @@ class SearchPanel(QWidget):  # {{{
         la.setVisible(False)
         l.addWidget(la)
 
+    def go_back(self):
+        if self.anchor_cfi:
+            self.goto_cfi.emit(self.anchor_cfi)
+
     def update_hidden_message(self):
         self.hidden_message.setVisible(self.results.current_result_is_hidden)
 
@@ -699,6 +713,9 @@ class SearchPanel(QWidget):  # {{{
         self.last_hidden_text_warning = None
         self.search_tasks.put((search_query, current_name))
 
+    def set_anchor_cfi(self, pos_data):
+        self.anchor_cfi = pos_data['cfi']
+
     def run_searches(self):
         while True:
             x = self.search_tasks.get()

src/calibre/gui2/viewer/ui.py

@@ -141,6 +141,7 @@ class EbookViewer(MainWindow):
         w.search_requested.connect(self.start_search)
         w.hide_search_panel.connect(self.search_dock.close)
         w.count_changed.connect(self.search_results_count_changed)
+        w.goto_cfi.connect(self.goto_cfi)
         self.search_dock.setWidget(w)
         self.search_dock.visibilityChanged.connect(self.search_widget.visibility_changed)
 
@@ -315,6 +316,7 @@ class EbookViewer(MainWindow):
     def start_search(self, search_query):
         name = self.web_view.current_content_file
         if name:
+            self.web_view.get_current_cfi(self.search_widget.set_anchor_cfi)
             self.search_widget.start_search(search_query, name)
             self.web_view.setFocus(Qt.OtherFocusReason)
 
@@ -350,9 +352,12 @@ class EbookViewer(MainWindow):
         # annotations will be saved in book file on exit
         self.save_annotations(in_book_file=False)
 
-    def bookmark_activated(self, cfi):
+    def goto_cfi(self, cfi):
         self.web_view.goto_cfi(cfi)
 
+    def bookmark_activated(self, cfi):
+        self.goto_cfi(cfi)
+
     def view_image(self, name):
         path = get_path_for_name(name)
         if path: