Added infrastructure for vector editing undo/redo functionality.

Note - when implementing edit tools for vector layer:
All editation should be done between beginEditCommand() and endEditCommand()
calls so that the operation are stored. 

Note - when doing changes inside QgsVectorLayer code:
When doing any changes inside QgsVectorLayer they should be done using edit*() functions
and _not_ directly e.g. mChangedGeometries[fid] = (...) otherwise the change won't be
stored in the undo stack and it would lead to invalid behaviour of undo.


git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@10920 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: wonder

python/core/qgsmaplayer.sip

@@ -249,6 +249,9 @@ public:
      */
     virtual QString saveNamedStyle( const QString theURI, bool & theResultFlag );	
 
+    /** Return pointer to layer's undo stack */
+    QUndoStack* undoStack();
+
 public slots:
 
     /** Event handler for when a coordinate transform fails due to bad vertex error */

python/core/qgsvectorlayer.sip

@@ -389,6 +389,25 @@ public:
     */
     QgsVectorOverlay* findOverlayByType( const QString& typeName );
 
+
+    /**
+     * Create edit command for undo/redo operations
+     * @param text text which is to be displayed in undo window
+     */
+    void beginEditCommand(QString text);
+
+    /** Finish edit command and add it to undo/redo stack */
+    void endEditCommand();
+
+    /** Destroy active command and deletes all changes in it */
+    void destroyEditCommand();
+
+    /** Execute undo operation. To be called only from QgsVectorLayerUndoCommand. */
+    // (not necessary) void undoEditCommand(QgsUndoCommand* cmd);
+
+    /** Execute redo operation. To be called only from QgsVectorLayerUndoCommand. */
+    // (not necessary) void redoEditCommand(QgsUndoCommand* cmd);
+
 public slots:
 
   /** Select feature by its ID, optionally emit signal selectionChanged() */

src/core/CMakeLists.txt

@@ -51,6 +51,7 @@ SET(QGIS_CORE_SRCS
   qgsvectordataprovider.cpp
   qgsvectorfilewriter.cpp
   qgsvectorlayer.cpp
+  qgsvectorlayerundocommand.cpp
   qgsvectoroverlay.cpp
 
   composer/qgscomposeritem.cpp

src/core/qgsmaplayer.cpp

@@ -715,3 +715,11 @@ QString QgsMapLayer::saveNamedStyle( const QString theURI, bool & theResultFlag
 
   return myErrorMessage;
 }
+
+
+
+
+QUndoStack* QgsMapLayer::undoStack()
+{
+  return &mUndoStack;
+}

src/core/qgsmaplayer.h

@@ -23,6 +23,7 @@
 #include <map>
 
 #include <QObject>
+#include <QUndoStack>
 
 #include "qgsrectangle.h"
 
@@ -259,6 +260,9 @@ class CORE_EXPORT QgsMapLayer : public QObject
      */
     virtual bool writeSymbology( QDomNode&, QDomDocument& doc, QString& errorMessage ) const = 0;
 
+    /** Return pointer to layer's undo stack */
+    QUndoStack* undoStack();
+
   public slots:
 
     /** Event handler for when a coordinate transform fails due to bad vertex error */
@@ -356,6 +360,8 @@ class CORE_EXPORT QgsMapLayer : public QObject
     /** A flag that tells us whether to use the above vars to restrict layer visibility */
     bool mScaleBasedVisibility;
 
+    QUndoStack mUndoStack;
+
 };
 
 #endif