Edit book: Add an "Open with" action to the context menu of the files browser to easily open files with external programs. Fixes #1860462 [[Enhancement] External Editor Needed](https://bugs.launchpad.net/calibre/+bug/1860462)

src/calibre/gui2/tweak_book/boss.py

@@ -64,12 +64,14 @@ from calibre.gui2.tweak_book.widgets import (
     AddCover, BusyCursor, FilterCSS, ImportForeign, InsertLink, InsertSemantics,
     InsertTag, MultiSplit, QuickOpen, RationalizeFolders
 )
-from calibre.ptempfile import TemporaryDirectory
+from calibre.ptempfile import PersistentTemporaryDirectory, TemporaryDirectory
 from calibre.utils.config import JSONConfig
 from calibre.utils.icu import numeric_sort_key
 from calibre.utils.imghdr import identify
 from calibre.utils.tdir_in_cache import tdir_in_cache
-from polyglot.builtins import iteritems, itervalues, string_or_bytes, map, unicode_type
+from polyglot.builtins import (
+    iteritems, itervalues, map, string_or_bytes, unicode_type
+)
 from polyglot.urllib import urlparse
 
 _diff_dialogs = []
@@ -138,6 +140,7 @@ class Boss(QObject):
         fl.link_stylesheets_requested.connect(self.link_stylesheets_requested)
         fl.initiate_file_copy.connect(self.copy_files_to_clipboard)
         fl.initiate_file_paste.connect(self.paste_files_from_clipboard)
+        fl.open_file_with.connect(self.open_file_with)
         self.gui.central.current_editor_changed.connect(self.apply_current_editor_state)
         self.gui.central.close_requested.connect(self.editor_close_requested)
         self.gui.central.search_panel.search_triggered.connect(self.search)
@@ -1361,6 +1364,29 @@ class Boss(QObject):
                         raise
             self.export_file(name, dest)
 
+    def open_file_with(self, file_name, fmt, entry):
+        if file_name in editors and not editors[file_name].is_synced_to_container:
+            self.commit_editor_to_container(file_name)
+        with current_container().open(file_name) as src:
+            tdir = PersistentTemporaryDirectory(suffix='-ee-ow')
+            with open(os.path.join(tdir, os.path.basename(file_name)), 'wb') as dest:
+                shutil.copyfileobj(src, dest)
+        from calibre.gui2.open_with import run_program
+        run_program(entry, dest.name, self)
+        if question_dialog(self.gui, _('File opened'), _(
+            'When you are done editing {0} click "Update" to update'
+            ' the file in the book or "Discard" to lose any changes.').format(file_name),
+            yes_text=_('Import'), no_text=_('Discard')
+        ):
+            self.add_savepoint(_('Before: Replace %s') % file_name)
+            with open(dest.name, 'rb') as src, current_container().open(file_name, 'wb') as cdest:
+                shutil.copyfileobj(src, cdest)
+            self.apply_container_update_to_gui()
+        try:
+            shutil.rmtree(tdir)
+        except Exception:
+            pass
+
     @in_thread_job
     def copy_files_to_clipboard(self, names):
         names = tuple(names)

src/calibre/gui2/tweak_book/file_list.py

@@ -202,6 +202,7 @@ class FileList(QTreeWidget):
     link_stylesheets_requested = pyqtSignal(object, object, object)
     initiate_file_copy = pyqtSignal(object)
     initiate_file_paste = pyqtSignal()
+    open_file_with = pyqtSignal(object, object, object)
 
     def __init__(self, parent=None):
         QTreeWidget.__init__(self, parent)
@@ -540,6 +541,8 @@ class FileList(QTreeWidget):
                 m.addAction(_('Replace %s with file...') % n, partial(self.replace, cn))
             if num > 1:
                 m.addAction(QIcon(I('save.png')), _('Export all %d selected files') % num, self.export_selected)
+            if cn not in container.names_that_must_not_be_changed:
+                self.add_open_with_actions(m, cn)
 
             m.addSeparator()
 
@@ -583,6 +586,35 @@ class FileList(QTreeWidget):
         if len(list(m.actions())) > 0:
             m.popup(self.mapToGlobal(point))
 
+    def add_open_with_actions(self, menu, file_name):
+        from calibre.gui2.open_with import populate_menu, edit_programs
+        fmt = file_name.rpartition('.')[-1].lower()
+        if not fmt:
+            return
+        m = QMenu(_('Open %s with...') % file_name)
+
+        def connect_action(ac, entry):
+            connect_lambda(ac.triggered, self, lambda self: self.open_with(file_name, fmt, entry))
+
+        populate_menu(m, connect_action, fmt)
+        if len(m.actions()) == 0:
+            menu.addAction(_('Open %s with...') % file_name, partial(self.choose_open_with, file_name, fmt))
+        else:
+            m.addSeparator()
+            m.addAction(_('Add other application for %s files...') % fmt.upper(), partial(self.choose_open_with, file_name, fmt))
+            m.addAction(_('Edit Open With applications...'), partial(edit_programs, fmt, file_name))
+            menu.addMenu(m)
+            menu.ow = m
+
+    def choose_open_with(self, file_name, fmt):
+        from calibre.gui2.open_with import choose_program
+        entry = choose_program(fmt, self)
+        if entry is not None:
+            self.open_with(file_name, fmt, entry)
+
+    def open_with(self, file_name, fmt, entry):
+        self.open_file_with.emit(file_name, fmt, entry)
+
     def index_of_name(self, name):
         for category, parent in iteritems(self.categories):
             for i in range(parent.childCount()):