Edit book: Add a tool to view the list of checkpoints and compare the current state of the book to the state at the specified checkpoint.

src/calibre/gui2/tweak_book/boss.py

@@ -109,6 +109,8 @@ class Boss(QObject):
         self.gui.check_book.fix_requested.connect(self.fix_requested)
         self.gui.toc_view.navigate_requested.connect(self.link_clicked)
         self.gui.image_browser.image_activated.connect(self.image_activated)
+        self.gui.checkpoints.revert_requested.connect(self.revert_requested)
+        self.gui.checkpoints.compare_requested.connect(self.compare_requested)
 
     def preferences(self):
         p = Preferences(self.gui)
@@ -411,11 +413,11 @@ class Boss(QObject):
             d.line_activated.connect(line_activated)
         return d
 
-    def show_current_diff(self, allow_revert=True):
+    def show_current_diff(self, allow_revert=True, to_container=None):
         self.commit_all_editors_to_container()
         d = self.create_diff_dialog()
         d.revert_requested.connect(partial(self.revert_requested, self.global_undo.previous_container))
-        d.container_diff(self.global_undo.previous_container, self.global_undo.current_container)
+        d.container_diff(to_container or self.global_undo.previous_container, self.global_undo.current_container)
 
     def compare_book(self):
         self.commit_all_editors_to_container()
@@ -434,6 +436,9 @@ class Boss(QObject):
         set_current_container(nc)
         self.apply_container_update_to_gui()
 
+    def compare_requested(self, container):
+        self.show_current_diff(to_container=container)
+
     # Renaming {{{
 
     def rationalize_folders(self):

src/calibre/gui2/tweak_book/ui.py

@@ -25,6 +25,7 @@ from calibre.gui2.tweak_book import current_container, tprefs, actions, capitali
 from calibre.gui2.tweak_book.file_list import FileListWidget
 from calibre.gui2.tweak_book.job import BlockingJob
 from calibre.gui2.tweak_book.boss import Boss
+from calibre.gui2.tweak_book.undo import CheckpointView
 from calibre.gui2.tweak_book.preview import Preview
 from calibre.gui2.tweak_book.search import SearchPanel
 from calibre.gui2.tweak_book.check import Check
@@ -581,6 +582,13 @@ class Main(MainWindow):
         d.close()  # Hidden by default
         d.visibilityChanged.connect(self.toc_view.visibility_changed)
 
+        d = create(_('Checkpoints'), 'checkpoints')
+        d.setAllowedAreas(Qt.LeftDockWidgetArea | Qt.RightDockWidgetArea | Qt.BottomDockWidgetArea | Qt.TopDockWidgetArea)
+        self.checkpoints = CheckpointView(self.boss.global_undo, parent=d)
+        d.setWidget(self.checkpoints)
+        self.addDockWidget(Qt.LeftDockWidgetArea, d)
+        d.close()  # Hidden by default
+
     def resizeEvent(self, ev):
         self.blocking_job.resize(ev.size())
         return super(Main, self).resizeEvent(ev)

src/calibre/gui2/tweak_book/undo.py

@@ -8,6 +8,14 @@ __copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
 
 import shutil
 
+from PyQt4.Qt import (
+    QAbstractListModel, Qt, QModelIndex, QVariant, QApplication, QWidget,
+    QGridLayout, QListView, QStyledItemDelegate, pyqtSignal, QPushButton, QIcon)
+
+from calibre.gui2 import NONE, error_dialog
+
+ROOT = QModelIndex()
+
 MAX_SAVEPOINTS = 100
 
 def cleanup(containers):
@@ -23,12 +31,35 @@ class State(object):
         self.container = container
         self.message = None
 
-class GlobalUndoHistory(object):
+class GlobalUndoHistory(QAbstractListModel):
 
-    def __init__(self):
+    def __init__(self, parent=None):
+        QAbstractListModel.__init__(self, parent)
         self.states = []
         self.pos = 0
 
+    def rowCount(self, parent=ROOT):
+        return len(self.states)
+
+    def data(self, index, role=Qt.DisplayRole):
+        if role == Qt.DisplayRole:
+            row = index.row()
+            msg = self.states[row].message
+            if self.pos == row:
+                msg = _('Current state')
+            elif not msg:
+                msg = _('[Unnamed state]')
+            else:
+                msg = _('Before %s') % msg
+            return QVariant(msg)
+        if role == Qt.FontRole and index.row() == self.pos:
+            f = QApplication.instance().font()
+            f.setBold(True)
+            return QVariant(f)
+        if role == Qt.UserRole:
+            return QVariant(self.states[index.row()])
+        return NONE
+
     @property
     def current_container(self):
         return self.states[self.pos].container
@@ -40,6 +71,7 @@ class GlobalUndoHistory(object):
     def open_book(self, container):
         self.states = [State(container)]
         self.pos = 0
+        self.reset()
 
     def add_savepoint(self, new_container, message):
         try:
@@ -48,14 +80,23 @@ class GlobalUndoHistory(object):
             raise IndexError('The checkpoint stack has an incorrect position pointer. This should never happen: self.pos = %r, len(self.states) = %r' % (
                 self.pos, len(self.states)))
         extra = self.states[self.pos+1:]
+        if extra:
+            self.beginRemoveRows(ROOT, self.pos+1, len(self.states) - 1)
         cleanup(extra)
         self.states = self.states[:self.pos+1]
+        if extra:
+            self.endRemoveRows()
+        self.beginInsertRows(ROOT, self.pos+1, self.pos+1)
         self.states.append(State(new_container))
         self.pos += 1
+        self.endInsertRows()
+        self.dataChanged.emit(self.index(self.pos-1), self.index(self.pos))
         if len(self.states) > MAX_SAVEPOINTS:
             num = len(self.states) - MAX_SAVEPOINTS
+            self.beginRemoveRows(ROOT, 0, num - 1)
             cleanup(self.states[:num])
             self.states = self.states[num:]
+            self.endRemoveRows()
 
     def rewind_savepoint(self):
         ''' Revert back to the last save point, should only be used immediately
@@ -64,8 +105,11 @@ class GlobalUndoHistory(object):
         where you create savepoint, perform some operation, operation fails, so
         revert to state before creating savepoint. '''
         if self.pos > 0 and self.pos == len(self.states) - 1:
+            self.beginRemoveRows(ROOT, self.pos, self.pos)
             self.pos -= 1
             cleanup([self.states.pop().container])
+            self.endRemoveRows()
+            self.dataChanged.emit(self.index(self.pos))
             ans = self.current_container
             ans.message = None
             return ans
@@ -73,17 +117,22 @@ class GlobalUndoHistory(object):
     def undo(self):
         if self.pos > 0:
             self.pos -= 1
+            self.dataChanged.emit(self.index(self.pos), self.index(self.pos+1))
             return self.current_container
 
     def redo(self):
         if self.pos < len(self.states) - 1:
             self.pos += 1
+            self.dataChanged.emit(self.index(self.pos-1), self.index(self.pos))
             return self.current_container
 
     def revert_to(self, container):
         for i, state in enumerate(self.states):
             if state.container is container:
+                opos = self.pos
                 self.pos = i
+                for x in (i, opos):
+                    self.dataChanged.emit(self.index(x), self.index(x))
                 return container
 
     @property
@@ -106,3 +155,69 @@ class GlobalUndoHistory(object):
             return ''
         return self.states[self.pos].message or ''
 
+class SpacedDelegate(QStyledItemDelegate):
+
+    def sizeHint(self, *args):
+        ans = QStyledItemDelegate.sizeHint(self, *args)
+        ans.setHeight(ans.height() + 4)
+        return ans
+
+class CheckpointView(QWidget):
+
+    revert_requested = pyqtSignal(object)
+    compare_requested = pyqtSignal(object)
+
+    def __init__(self, model, parent=None):
+        QWidget.__init__(self, parent)
+        self.l = l = QGridLayout(self)
+        self.setLayout(l)
+        self.setContentsMargins(0, 0, 0, 0)
+
+        self.view = v = QListView(self)
+        self.d = SpacedDelegate(v)
+        v.doubleClicked.connect(self.double_clicked)
+        v.setItemDelegate(self.d)
+        v.setModel(model)
+        l.addWidget(v, 0, 0, 1, -1)
+        model.dataChanged.connect(self.data_changed)
+
+        self.rb = b = QPushButton(QIcon(I('edit-undo.png')), _('&Revert to'), self)
+        b.setToolTip(_('Revert the book to the selected checkpoint'))
+        b.clicked.connect(self.revert_clicked)
+        l.addWidget(b, 1, 1)
+
+        self.cb = b = QPushButton(QIcon(I('diff.png')), _('&Compare'), self)
+        b.setToolTip(_('Compare the state of the book at the selected checkpoint with the current state'))
+        b.clicked.connect(self.compare_clicked)
+        l.addWidget(b, 1, 0)
+
+    def data_changed(self, *args):
+        self.view.clearSelection()
+        m = self.view.model()
+        sm = self.view.selectionModel()
+        sm.select(m.index(m.pos), sm.ClearAndSelect)
+        self.view.setCurrentIndex(m.index(m.pos))
+
+    def double_clicked(self, index):
+        pass  # Too much danger of accidental double click
+
+    def revert_clicked(self):
+        m = self.view.model()
+        row = self.view.currentIndex().row()
+        if row < 0:
+            return
+        if row == m.pos:
+            return error_dialog(self, _('Cannot revert'), _(
+                'Cannot revert to the current state'), show=True)
+        self.revert_requested.emit(m.states[row].container)
+
+    def compare_clicked(self):
+        m = self.view.model()
+        row = self.view.currentIndex().row()
+        if row < 0:
+            return
+        if row == m.pos:
+            return error_dialog(self, _('Cannot compare'), _(
+                'There is no point comparing the current state to itself'), show=True)
+        self.compare_requested.emit(m.states[row].container)
+