Allow comparing the ORIGINAL_EPUB version of a book to the EPUB version by right clicking on the ORIGINAL_EPUB format in the book details panel.

src/calibre/db/cache.py

@@ -671,8 +671,9 @@ class Cache(object):
         '''
         Return absolute path to the ebook file of format `format`
 
-        Currently used only in calibredb list, the viewer, edit book and the
+        Currently used only in calibredb list, the viewer, edit book,
-        catalogs (via get_data_as_dict()).
+        compare_format to original format and the catalogs (via
+        get_data_as_dict()).
 
         Apart from the viewer, I don't believe any of the others do any file
         I/O with the results of this call.

src/calibre/gui2/book_details.py

@@ -413,6 +413,7 @@ class BookInfo(QWebView):
     remove_format = pyqtSignal(int, object)
     save_format = pyqtSignal(int, object)
     restore_format = pyqtSignal(int, object)
+    compare_format = pyqtSignal(int, object)
     copy_link = pyqtSignal(object)
     manage_author = pyqtSignal(object)
 
@@ -433,7 +434,7 @@ class BookInfo(QWebView):
         for x, icon in [
             ('remove_format', 'trash.png'), ('save_format', 'save.png'),
             ('restore_format', 'edit-undo.png'), ('copy_link','edit-copy.png'),
-            ('manage_author', 'user_profile.png')]:
+            ('manage_author', 'user_profile.png'), ('compare_format', 'diff.png')]:
             ac = QAction(QIcon(I(icon)), '', self)
             ac.current_fmt = None
             ac.current_url = None
@@ -458,6 +459,9 @@ class BookInfo(QWebView):
     def restore_format_triggerred(self):
         self.context_action_triggered('restore_format')
 
+    def compare_format_triggerred(self):
+        self.context_action_triggered('compare_format')
+
     def copy_link_triggerred(self):
         self.context_action_triggered('copy_link')
 
@@ -517,20 +521,31 @@ class BookInfo(QWebView):
             if url.startswith('format:'):
                 parts = url.split(':')
                 try:
-                    book_id, fmt = int(parts[1]), parts[2]
+                    book_id, fmt = int(parts[1]), parts[2].upper()
                 except:
                     import traceback
                     traceback.print_exc()
                 else:
+                    from calibre.gui2.ui import get_gui
+                    db = get_gui().current_db.new_api
+                    ofmt = fmt.upper() if fmt.startswith('ORIGINAL_') else 'ORIGINAL_' + fmt
+                    fmts = {x.upper() for x in db.formats(book_id)}
                     for a, t in [('remove', _('Delete the %s format')),
                         ('save', _('Save the %s format to disk')),
                         ('restore', _('Restore the %s format')),
+                        ('compare', ''),
                     ]:
-                        if a == 'restore' and not fmt.upper().startswith('ORIGINAL_'):
+                        if a == 'restore' and not fmt.startswith('ORIGINAL_'):
                             continue
+                        if a == 'compare':
+                            if ofmt not in fmts:
+                                continue
+                            t = _('Compare to the %s format') % (fmt[9:] if fmt.startswith('ORIGINAL_') else ofmt)
+                        else:
+                            t = t % fmt
                         ac = getattr(self, '%s_format_action'%a)
                         ac.current_fmt = (book_id, fmt)
-                        ac.setText(t%parts[2])
+                        ac.setText(t)
                         menu.addAction(ac)
         if len(menu.actions()) > 0:
             menu.exec_(ev.globalPos())
@@ -635,6 +650,7 @@ class BookDetails(QWidget):  # {{{
     remove_specific_format = pyqtSignal(int, object)
     save_specific_format = pyqtSignal(int, object)
     restore_specific_format = pyqtSignal(int, object)
+    compare_specific_format = pyqtSignal(int, object)
     copy_link = pyqtSignal(object)
     remote_file_dropped = pyqtSignal(object, object)
     files_dropped = pyqtSignal(object, object)
@@ -706,6 +722,7 @@ class BookDetails(QWidget):  # {{{
         self.book_info.remove_format.connect(self.remove_specific_format)
         self.book_info.save_format.connect(self.save_specific_format)
         self.book_info.restore_format.connect(self.restore_specific_format)
+        self.book_info.compare_format.connect(self.compare_specific_format)
         self.book_info.copy_link.connect(self.copy_link)
         self.book_info.manage_author.connect(self.manage_author)
         self.setCursor(Qt.PointingHandCursor)

src/calibre/gui2/init.py

@@ -449,6 +449,7 @@ class LayoutMixin(object):  # {{{
         self.book_details.view_device_book.connect(
                 self.iactions['View'].view_device_book)
         self.book_details.manage_author.connect(lambda author:self.do_author_sort_edit(self, author, select_sort=False, select_link=False))
+        self.book_details.compare_specific_format.connect(self.compare_format)
 
         m = self.library_view.model()
         if m.rowCount(None) > 0:
@@ -475,6 +476,18 @@ class LayoutMixin(object):  # {{{
         if url:
             QApplication.clipboard().setText(url)
 
+    def compare_format(self, book_id, fmt):
+        db = self.current_db.new_api
+        ofmt = fmt
+        if fmt.startswith('ORIGINAL_'):
+            fmt = fmt.partition('_')[-1]
+        else:
+            ofmt = 'ORIGINAL_' + fmt
+        path1, path2 = db.format_abspath(book_id, ofmt), db.format_abspath(book_id, fmt)
+        from calibre.gui2.tweak_book.diff.main import compare_books
+        compare_books(path1, path2, parent=self, revert_msg=_('Restore %s') % ofmt, revert_callback=partial(
+            self.iactions['Remove Books'].restore_format, book_id, ofmt))
+
     def save_layout_state(self):
         for x in ('library', 'memory', 'card_a', 'card_b'):
             getattr(self, x+'_view').save_state()

src/calibre/gui2/tweak_book/diff/main.py

@@ -11,7 +11,7 @@ from functools import partial
 from PyQt4.Qt import (
     QGridLayout, QToolButton, QIcon, QRadioButton, QMenu, QApplication, Qt,
     QSize, QWidget, QLabel, QStackedLayout, QPainter, QRect, QVBoxLayout,
-    QCursor, QEventLoop, QKeySequence, pyqtSignal)
+    QCursor, QEventLoop, QKeySequence, pyqtSignal, QTimer)
 
 from calibre.ebooks.oeb.polish.container import Container
 from calibre.gui2 import info_dialog
@@ -107,8 +107,8 @@ def container_diff(left, right):
         left_names -= samefile_names
         right_names -= samefile_names
 
-        cache, changed_names, renamed_names, removed_names, added_names = changed_files(
+    cache, changed_names, renamed_names, removed_names, added_names = changed_files(
-            left_names, right_names, left.raw_data, right.raw_data)
+        left_names, right_names, left.raw_data, right.raw_data)
 
     def syntax(container, name):
         mt = container.mime_map[name]
@@ -141,6 +141,7 @@ class Diff(Dialog):
         return QSize(int(0.9 * geom.width()), int(0.8 * geom.height()))
 
     def setup_ui(self):
+        self.setWindowIcon(QIcon(I('diff.png')))
         self.stacks = st = QStackedLayout(self)
         self.busy = BusyWidget(self)
         self.w = QWidget(self)
@@ -300,6 +301,18 @@ class Diff(Dialog):
                 return
             return Dialog.keyPressEvent(self, ev)
 
+def compare_books(path1, path2, revert_msg=None, revert_callback=None, parent=None):
+    d = Diff(parent=parent, revert_button_msg=revert_msg)
+    if revert_msg is not None:
+        d.revert_requested.connect(revert_callback)
+    QTimer.singleShot(0, partial(d.ebook_diff, path1, path2))
+    d.exec_()
+    try:
+        d.revert_requested.disconnect()
+    except:
+        pass
+    d.break_cycles()
+
 if __name__ == '__main__':
     import sys
     app = QApplication([])