Book list: Allow drag and drop of books onto other books to merge the book records. Fixes #1775123 [[Enhancement] Merge books with Drag/Drop](https://bugs.launchpad.net/calibre/+bug/1775123)

src/calibre/gui2/actions/edit_metadata.py

@@ -480,6 +480,33 @@ class EditMetadataAction(InterfaceAction):
             self.gui.library_view.select_rows(book_ids)
 
     # Merge books {{{
+
+    def confirm_large_merge(self, num):
+        if num < 5:
+            return True
+        return confirm('<p>'+_(
+            'You are about to merge very many ({}) books. '
+            'Are you <b>sure</b> you want to proceed?').format(num) + '</p>',
+            'merge_too_many_books', self.gui)
+
+    def books_dropped(self, merge_map):
+        for dest_id, src_ids in merge_map.iteritems():
+            if not self.confirm_large_merge(len(src_ids) + 1):
+                continue
+            from calibre.gui2.dialogs.confirm_merge import merge_drop
+            merge_metadata, merge_formats, delete_books = merge_drop(dest_id, src_ids, self.gui)
+            if merge_metadata is None:
+                return
+            if merge_formats:
+                self.add_formats(dest_id, self.formats_for_ids(list(src_ids)))
+            if merge_metadata:
+                self.merge_metadata(dest_id, src_ids)
+            if delete_books:
+                self.delete_books_after_merge(src_ids)
+            # leave the selection highlight on the target book
+            row = self.gui.library_view.ids_to_rows([dest_id])[dest_id]
+            self.gui.library_view.set_current_row(row)
+
     def merge_books(self, safe_merge=False, merge_only_formats=False):
         '''
         Merge selected books in library.
@@ -495,12 +522,8 @@ class EditMetadataAction(InterfaceAction):
             return error_dialog(self.gui, _('Cannot merge books'),
                         _('At least two books must be selected for merging'),
                         show=True)
-        if len(rows) > 5:
+        if not self.confirm_large_merge(len(rows)):
-            if not confirm('<p>'+_(
+            return
-                'You are about to merge more than 5 books.  '
-                'Are you <b>sure</b> you want to proceed?') + '</p>',
-                'merge_too_many_books', self.gui):
-                return
 
         dest_id, src_ids = self.books_to_merge(rows)
         mi = self.gui.current_db.new_api.get_proxy_metadata(dest_id)
@@ -566,10 +589,10 @@ class EditMetadataAction(InterfaceAction):
                     self.gui.library_view.model().db.add_format(dest_id, fmt, f, index_is_id=True,
                             notify=False, replace=replace)
 
-    def formats_for_books(self, rows):
+    def formats_for_ids(self, ids):
         m = self.gui.library_view.model()
         ans = []
-        for id_ in map(m.id, rows):
+        for id_ in ids:
             dbfmts = m.db.formats(id_, index_is_id=True)
             if dbfmts:
                 for fmt in dbfmts.split(','):
@@ -581,6 +604,10 @@ class EditMetadataAction(InterfaceAction):
                         continue
         return ans
 
+    def formats_for_books(self, rows):
+        m = self.gui.library_view.model()
+        return self.formats_for_ids(map(m.id, rows))
+
     def books_to_merge(self, rows):
         src_ids = []
         m = self.gui.library_view.model()

src/calibre/gui2/dialogs/confirm_merge.py

@@ -6,19 +6,48 @@ from __future__ import (unicode_literals, division, absolute_import,
 __license__ = 'GPL v3'
 __copyright__ = '2015, Kovid Goyal <kovid at kovidgoyal.net>'
 
+from functools import partial
 from PyQt5.Qt import (
-    QVBoxLayout, QSplitter, QWidget, QLabel, QCheckBox, QTextBrowser
+    QVBoxLayout, QSplitter, QWidget, QLabel, QCheckBox, QTextBrowser, Qt,
 )
 
 from calibre.ebooks.metadata import authors_to_string
 from calibre.ebooks.metadata.book.base import field_metadata
-from calibre.gui2 import dynamic
+from calibre.gui2 import dynamic, gprefs
 from calibre.gui2.widgets2 import Dialog
 from calibre.gui2.dialogs.confirm_delete import confirm_config_name
 from calibre.utils.config import tweaks
 from calibre.utils.date import format_date
 
 
+class Target(QTextBrowser):
+
+    def __init__(self, mi, parent=None):
+        QTextBrowser.__init__(self, parent)
+        series = ''
+        fm = field_metadata
+        if mi.series:
+            series = _('{num} of {series}').format(num=mi.format_series_index(), series='<i>%s</i>' % mi.series)
+        self.setHtml('''
+<h3 style="text-align:center">{mb}</h3>
+<p><b>{title}</b> - <i>{authors}</i><br></p>
+<table>
+<tr><td>{fm[timestamp][name]}:</td><td>{date}</td></tr>
+<tr><td>{fm[pubdate][name]}:</td><td>{published}</td></tr>
+<tr><td>{fm[formats][name]}:</td><td>{formats}</td></tr>
+<tr><td>{fm[series][name]}:</td><td>{series}</td></tr>
+</table>
+        '''.format(
+            mb=_('Target book'),
+            title=mi.title,
+            authors=authors_to_string(mi.authors),
+            date=format_date(mi.timestamp, tweaks['gui_timestamp_display_format']), fm=fm,
+            published=(format_date(mi.pubdate, tweaks['gui_pubdate_display_format']) if mi.pubdate else ''),
+            formats=', '.join(mi.formats or ()),
+            series=series
+        ))
+
+
 class ConfirmMerge(Dialog):
 
     def __init__(self, msg, name, parent, mi):
@@ -44,29 +73,7 @@ class ConfirmMerge(Dialog):
         c.stateChanged.connect(self.toggle)
         l.addWidget(c)
 
-        self.right = r = QTextBrowser(self)
+        self.right = r = Target(self.mi, self)
-        series = ''
-        mi, fm = self.mi, field_metadata
-        if mi.series:
-            series = _('{num} of {series}').format(num=mi.format_series_index(), series='<i>%s</i>' % mi.series)
-        r.setHtml('''
-<h3 style="text-align:center">{mb}</h3>
-<p><b>{title}</b> - <i>{authors}</i><br></p>
-<table>
-<tr><td>{fm[timestamp][name]}:</td><td>{date}</td></tr>
-<tr><td>{fm[pubdate][name]}:</td><td>{published}</td></tr>
-<tr><td>{fm[formats][name]}:</td><td>{formats}</td></tr>
-<tr><td>{fm[series][name]}:</td><td>{series}</td></tr>
-</table>
-        '''.format(
-            mb=_('Target book'),
-            title=mi.title,
-            authors=authors_to_string(mi.authors),
-            date=format_date(mi.timestamp, tweaks['gui_timestamp_display_format']), fm=fm,
-            published=(format_date(mi.pubdate, tweaks['gui_pubdate_display_format']) if mi.pubdate else ''),
-            formats=', '.join(mi.formats or ()),
-            series=series
-        ))
         s.addWidget(r)
 
     def toggle(self):
@@ -84,3 +91,103 @@ def confirm_merge(msg, name, parent, mi):
         return True
     d = ConfirmMerge(msg, name, parent, mi)
     return d.exec_() == d.Accepted
+
+
+class ChooseMerge(Dialog):
+
+    def __init__(self, dest_id, src_ids, gui):
+        self.dest_id, self.src_ids = dest_id, src_ids
+        self.mi = gui.current_db.new_api.get_metadata(dest_id)
+        Dialog.__init__(self, _('Merge books'), 'choose-merge-dialog', parent=gui)
+
+    def setup_ui(self):
+        self.l = l = QVBoxLayout(self)
+        self.splitter = s = QSplitter(self)
+        s.setChildrenCollapsible(False)
+        l.addWidget(s), l.addWidget(self.bb)
+        self.bb.setStandardButtons(self.bb.Yes | self.bb.No)
+        self.left = w = QWidget(self)
+        s.addWidget(w)
+        w.l = l = QVBoxLayout(w)
+        l.setContentsMargins(0, 0, 0, 0)
+
+        def cb(name, text, tt=''):
+            ans = QCheckBox(text)
+            l.addWidget(ans)
+            prefs_key = ans.prefs_key = 'choose-merge-cb-' + name
+            ans.setChecked(gprefs.get(prefs_key, True))
+            ans.stateChanged.connect(partial(self.state_changed, ans), type=Qt.QueuedConnection)
+            if tt:
+                ans.setToolTip(tt)
+            setattr(self, name, ans)
+            return ans
+
+        cb('merge_metadata', _('Merge metadata'), _(
+            'Merge the metadata of the selected books into the target book'))
+        cb('merge_formats', _('Merge formats'), _(
+            'Merge the book files of the selected books into the target book'))
+        cb('delete_books', _('Delete merged books'), _(
+            'Delete the selected books after merging'))
+        l.addStretch(10)
+        self.msg = la = QLabel(self)
+        la.setWordWrap(True)
+        l.addWidget(la)
+        self.update_msg()
+
+        self.right = r = Target(self.mi, self)
+        s.addWidget(r)
+
+    def state_changed(self, cb, state):
+        mm = self.merge_metadata.isChecked()
+        mf = self.merge_formats.isChecked()
+        if not mm and not mf:
+            (self.merge_metadata if cb is self.merge_formats else self.merge_formats).setChecked(True)
+        gprefs[cb.prefs_key] = cb.isChecked()
+        self.update_msg()
+
+    def update_msg(self):
+        mm = self.merge_metadata.isChecked()
+        mf = self.merge_formats.isChecked()
+        rm = self.delete_books.isChecked()
+        msg = '<p>'
+        if mm and mf:
+            msg += _(
+                'Book formats and metadata from the selected books'
+                ' will be merged into the target book ({title}).')
+        elif mf:
+            msg += _('Book formats from the selected books '
+            'will be merged into to the target book ({title}).'
+            ' Metadata in the target book will not be changed.')
+        elif mm:
+            msg += _('Metadata from the selected books '
+            'will be merged into to the target book ({title}).'
+            ' Formats will not be merged.')
+        msg += '<br>'
+        msg += _('All book formats of the first selected book will be kept.') + '<br><br>'
+        if rm:
+            msg += _('After being merged, the selected books will be <b>deleted</b>.')
+            if mf:
+                msg += '<br><br>' + _(
+                'Any duplicate formats in the selected books '
+                'will be permanently <b>deleted</b> from your calibre library.')
+        else:
+            if mf:
+                msg += _(
+                    'Any formats not in the target book will be added to it from the selected books.')
+        if not msg.endswith('<br>'):
+            msg += '<br><br>'
+
+        msg += _('Are you <b>sure</b> you want to proceed?') + '</p>'
+        msg = msg.format(title=self.mi.title)
+        self.msg.setText(msg)
+
+    @property
+    def merge_type(self):
+        return self.merge_metadata.isChecked(), self.merge_formats.isChecked(), self.delete_books.isChecked()
+
+
+def merge_drop(dest_id, src_ids, gui):
+    d = ChooseMerge(dest_id, src_ids, gui)
+    if d.exec_() != d.Accepted:
+        return None, None, None
+    return d.merge_type

src/calibre/gui2/init.py

@@ -41,6 +41,7 @@ class LibraryViewMixin(object):  # {{{
 
     def init_library_view_mixin(self, db):
         self.library_view.files_dropped.connect(self.iactions['Add Books'].files_dropped, type=Qt.QueuedConnection)
+        self.library_view.books_dropped.connect(self.iactions['Edit Metadata'].books_dropped, type=Qt.QueuedConnection)
         self.library_view.add_column_signal.connect(partial(self.iactions['Preferences'].do_config,
             initial_plugin=('Interface', 'Custom Columns')),
                 type=Qt.QueuedConnection)

src/calibre/gui2/library/alternate_views.py

@@ -206,12 +206,24 @@ def dragEnterEvent(self, event):
         int(event.possibleActions() & Qt.MoveAction) == 0:
         return
     paths = self.paths_from_event(event)
+    md = event.mimeData()
 
-    if paths:
+    if paths or md.hasFormat('application/calibre+from_library'):
         event.acceptProposedAction()
 
 
 def dropEvent(self, event):
+    md = event.mimeData()
+    if md.hasFormat('application/calibre+from_library'):
+        ids = set(map(int, bytes(md.data('application/calibre+from_library')).decode('utf-8').split(' ')))
+        row = self.indexAt(event.pos()).row()
+        if row > -1 and ids:
+            book_id = self.model().id(row)
+            if book_id:
+                self.books_dropped.emit({book_id: ids})
+                event.setDropAction(Qt.CopyAction)
+                event.accept()
+        return
     paths = self.paths_from_event(event)
     event.setDropAction(Qt.CopyAction)
     event.accept()
@@ -291,6 +303,7 @@ class AlternateViews(object):
         view.selectionModel().currentChanged.connect(self.slave_current_changed)
         view.selectionModel().selectionChanged.connect(self.slave_selection_changed)
         view.files_dropped.connect(self.main_view.files_dropped)
+        view.books_dropped.connect(self.main_view.books_dropped)
 
     def show_view(self, key=None):
         view = self.views[key]
@@ -663,6 +676,7 @@ class GridView(QListView):
 
     update_item = pyqtSignal(object)
     files_dropped = pyqtSignal(object)
+    books_dropped = pyqtSignal(object)
 
     def __init__(self, parent):
         QListView.__init__(self, parent)

src/calibre/gui2/library/views.py

@@ -204,6 +204,7 @@ class PreserveViewState(object):  # {{{
 class BooksView(QTableView):  # {{{
 
     files_dropped = pyqtSignal(object)
+    books_dropped = pyqtSignal(object)
     add_column_signal = pyqtSignal()
     is_library_view = True