Update undo/redo widget and vector layer rollback

- Allows for any number of undo/redo commands with only one refresh
- Significantly decreases time needed to cancel or redo many edits
- Disable undo/redo dock's widgets and toolbar actions when layer not in editing mode

src/app/qgisapp.cpp

@@ -5238,7 +5238,8 @@ bool QgisApp::toggleEditing( QgsMapLayer *layer, bool allowCancel )
           res = false;
         }
 
-        vlayer->triggerRepaint();
+        // canvas refreshes handled in QgsUndoWidget::indexChanged
+        //vlayer->triggerRepaint();
         break;
 
       default:
@@ -7215,11 +7216,16 @@ void QgisApp::activateDeactivateLayerRelatedActions( QgsMapLayer* layer )
         mActionToggleEditing->setEnabled( canChangeAttributes && !vlayer->isReadOnly() );
         mActionToggleEditing->setChecked( vlayer->isEditable() );
         mActionSaveEdits->setEnabled( canChangeAttributes && vlayer->isEditable() );
+        mUndoWidget->dockContents()->setEnabled( vlayer->isEditable() );
+        updateUndoActions();
       }
       else
       {
         mActionToggleEditing->setEnabled( false );
         mActionSaveEdits->setEnabled( false );
+        mUndoWidget->dockContents()->setEnabled( false );
+        mActionUndo->setEnabled( false );
+        mActionRedo->setEnabled( false );
       }
 
       if ( dprovider->capabilities() & QgsVectorDataProvider::AddFeatures )

src/app/qgsundowidget.cpp

@@ -37,6 +37,8 @@ QgsUndoWidget::QgsUndoWidget( QWidget * parent, QgsMapCanvas * mapCanvas )
   mMapCanvas = mapCanvas;
   mUndoView = NULL;
   mUndoStack = NULL;
+  mPreviousIndex = 0;
+  mPreviousCount = 0;
 }
 
 
@@ -80,13 +82,25 @@ void QgsUndoWidget::redoChanged( bool value )
   emit undoStackChanged();
 }
 
-
-void QgsUndoWidget::indexChanged( int value )
+void QgsUndoWidget::indexChanged( int curIndx )
 {
-  Q_UNUSED( value );
-  //redoButton->setDisabled( !value );
-  //canvas refresh
-  mMapCanvas->refresh();
+  // this is called twice when a non-current command is clicked in QUndoView
+  //   first call has offset, second call will have offset of 0
+  int curCount = 0;
+  if ( mUndoStack )
+  {
+    curCount = mUndoStack->count();
+  }
+  bool cmdAdded = ( curIndx == curCount && mPreviousCount == ( curCount - 1 ) );
+  int offset = qAbs( mPreviousIndex - curIndx );
+  // avoid refresh when only a command was added to stack (i.e. no undo/redo action)
+  if ( offset > 1 || ( offset == 1 && !cmdAdded ) )
+  {
+    mMapCanvas->refresh();
+  }
+
+  mPreviousIndex = curIndx;
+  mPreviousCount = curCount;
 }
 
 void QgsUndoWidget::undo( )
@@ -111,20 +125,19 @@ void QgsUndoWidget::setUndoStack( QUndoStack* undoStack )
   }
 
   mUndoStack = undoStack;
+  mPreviousIndex = mUndoStack->index();
+  mPreviousCount = mUndoStack->count();
 
   mUndoView = new QUndoView( dockWidgetContents );
   mUndoView->setStack( undoStack );
   mUndoView->setObjectName( "undoView" );
   gridLayout->addWidget( mUndoView, 0, 0, 1, 2 );
   setWidget( dockWidgetContents );
-  connect( mUndoStack,  SIGNAL( canUndoChanged( bool ) ), this, SLOT( undoChanged( bool ) ) );
-  connect( mUndoStack,  SIGNAL( canRedoChanged( bool ) ), this, SLOT( redoChanged( bool ) ) );
+  connect( mUndoStack, SIGNAL( canUndoChanged( bool ) ), this, SLOT( undoChanged( bool ) ) );
+  connect( mUndoStack, SIGNAL( canRedoChanged( bool ) ), this, SLOT( redoChanged( bool ) ) );
 
-  // indexChanged() triggers a refresh. but it gets triggered also when a new action
-  // is done, resulting in two refreshes. For now let's trigger the refresh from
-  // vector layer: it causes potentially multiple refreshes when moving more commands
-  // back, but avoids double refresh in common case when adding commands to the stack
-  //connect(mUndoStack,  SIGNAL(indexChanged(int)), this, SLOT(indexChanged(int)));
+  // gets triggered also when a new command is added to stack, and twice when clicking a command in QUndoView
+  connect( mUndoStack, SIGNAL( indexChanged( int ) ), this, SLOT( indexChanged( int ) ) );
 
   undoButton->setDisabled( !mUndoStack->canUndo() );
   redoButton->setDisabled( !mUndoStack->canRedo() );

src/app/qgsundowidget.h

@@ -58,6 +58,12 @@ class QgsUndoWidget : public QDockWidget
      */
     void destroyStack();
 
+    /**
+     * Access to dock's contents
+     * @note added in 1.9
+     */
+    QWidget* dockContents() { return dockWidgetContents; }
+
   public slots:
     /**
      * Changes undo stack which is displayed by undo view
@@ -77,7 +83,7 @@ class QgsUndoWidget : public QDockWidget
     /**
      * Slot to handle index changed signal
      */
-    void indexChanged( int value );
+    void indexChanged( int curIndx );
 
     /**
      * Undo operation called from button push
@@ -97,6 +103,8 @@ class QgsUndoWidget : public QDockWidget
     QUndoStack * mUndoStack;
     QgsMapCanvas* mMapCanvas;
 
+    int mPreviousIndex;
+    int mPreviousCount;
 };
 
 

src/core/qgsvectorlayer.cpp

@@ -4256,10 +4256,9 @@ bool QgsVectorLayer::rollBack()
 
   if ( isModified() )
   {
-    while ( undoStack()->canUndo() )
-    {
-      undoStack()->undo();
-    }
+    // new undo stack roll back method
+    // old method of calling every undo could cause many canvas refreshes
+    undoStack()->setIndex( 0 );
 
     Q_ASSERT( mAddedAttributeIds.isEmpty() );
     Q_ASSERT( mDeletedAttributeIds.isEmpty() );
@@ -5240,7 +5239,8 @@ void QgsVectorLayer::redoEditCommand( QgsUndoCommand* cmd )
   setModified( true );
 
   // it's not ideal to trigger refresh from here
-  triggerRepaint();
+  // canvas refreshes handled in QgsUndoWidget::indexChanged
+  //triggerRepaint();
 }
 
 void QgsVectorLayer::undoEditCommand( QgsUndoCommand* cmd )
@@ -5363,7 +5363,8 @@ void QgsVectorLayer::undoEditCommand( QgsUndoCommand* cmd )
   setModified( true );
 
   // it's not ideal to trigger refresh from here
-  triggerRepaint();
+  // canvas refreshes handled in QgsUndoWidget::indexChanged
+  //triggerRepaint();
 }
 
 void QgsVectorLayer::setCheckedState( int idx, QString checked, QString unchecked )