Add ability to undo/redo setting image as background

src/domain/UBGraphicsItemDelegate.cpp

@@ -596,16 +596,30 @@ void UBGraphicsItemDelegate::showHide(bool show)
     emit showOnDisplayChanged(show);
 }
 
+/**
+ * @brief Set delegate as background for the scene, replacing any existing background.
+ */
 void UBGraphicsItemDelegate::setAsBackground()
 {
     UBGraphicsScene* scene = castUBGraphicsScene();
     QGraphicsItem* item = delegated();
 
     if (scene && item) {
+        startUndoStep();
+
         item->resetTransform();
         item->setPos(item->sceneBoundingRect().width()/-2., item->sceneBoundingRect().height()/-2.);
 
         scene->setAsBackgroundObject(item);
+
+        UBGraphicsItemTransformUndoCommand *uc =
+                new UBGraphicsItemTransformUndoCommand(mDelegated,
+                                                       mPreviousPosition,
+                                                       mPreviousTransform,
+                                                       mPreviousZValue,
+                                                       mPreviousSize,
+                                                       true);
+        UBApplication::undoStack->push(uc);
     }
 }
 

src/domain/UBGraphicsItemTransformUndoCommand.cpp

@@ -30,12 +30,14 @@
 #include "UBGraphicsItemTransformUndoCommand.h"
 #include "UBResizableGraphicsItem.h"
 #include "domain/UBItem.h"
+#include "domain/UBGraphicsScene.h"
 
 #include "core/memcheck.h"
 
 UBGraphicsItemTransformUndoCommand::UBGraphicsItemTransformUndoCommand(QGraphicsItem* pItem,
      const QPointF& prevPos, const QTransform& prevTransform, const qreal& prevZValue,
-                                                                       const QSizeF& prevSize):UBUndoCommand()
+     const QSizeF& prevSize, bool setToBackground)
+    : UBUndoCommand()
 {
     mItem = pItem;
     mPreviousTransform = prevTransform;
@@ -52,6 +54,8 @@ UBGraphicsItemTransformUndoCommand::UBGraphicsItemTransformUndoCommand(QGraphics
 
     if (resizableItem)
         mCurrentSize = resizableItem->size();
+
+    mSetToBackground = setToBackground;
 }
 
 UBGraphicsItemTransformUndoCommand::~UBGraphicsItemTransformUndoCommand()
@@ -61,6 +65,13 @@ UBGraphicsItemTransformUndoCommand::~UBGraphicsItemTransformUndoCommand()
 
 void UBGraphicsItemTransformUndoCommand::undo()
 {
+    if (mSetToBackground) {
+        UBGraphicsScene* scene = dynamic_cast<UBGraphicsScene*>(mItem->scene());
+        if (scene && scene->isBackgroundObject(mItem)) {
+            scene->unsetBackgroundObject();
+        }
+    }
+
     mItem->setPos(mPreviousPosition);
     mItem->setTransform(mPreviousTransform);
     mItem->setZValue(mPreviousZValue);
@@ -73,6 +84,12 @@ void UBGraphicsItemTransformUndoCommand::undo()
 
 void UBGraphicsItemTransformUndoCommand::redo()
 {
+    if (mSetToBackground) {
+        UBGraphicsScene* scene = dynamic_cast<UBGraphicsScene*>(mItem->scene());
+        if (scene)
+            scene->setAsBackgroundObject(mItem);
+    }
+
     mItem->setPos(mCurrentPosition);
     mItem->setTransform(mCurrentTransform);
     mItem->setZValue(mCurrentZValue);

src/domain/UBGraphicsItemTransformUndoCommand.h

@@ -42,7 +42,8 @@ class UBGraphicsItemTransformUndoCommand : public UBUndoCommand
                                                 const QPointF& prevPos,
                                                 const QTransform& prevTransform,
                                                 const qreal& prevZValue,
-                                                const QSizeF& prevSize = QSizeF());
+                                                const QSizeF& prevSize = QSizeF(),
+                                                bool setToBackground = false);
         virtual ~UBGraphicsItemTransformUndoCommand();
 
         virtual int getType() const { return UBUndoType::undotype_GRAPHICITEMTRANSFORM; }
@@ -63,6 +64,8 @@ class UBGraphicsItemTransformUndoCommand : public UBUndoCommand
         qreal mPreviousZValue;
         qreal mCurrentZValue;
 
+        bool mSetToBackground;
+
 };
 
 #endif /* UBGRAPHICSITEMTRANSFORMUNDOCOMMAND_H_ */

src/domain/UBGraphicsScene.cpp

@@ -1983,6 +1983,21 @@ QGraphicsItem* UBGraphicsScene::setAsBackgroundObject(QGraphicsItem* item, bool
     return item;
 }
 
+void UBGraphicsScene::unsetBackgroundObject()
+{
+    if (!mBackgroundObject)
+        return;
+
+    mBackgroundObject->setFlag(QGraphicsItem::ItemIsSelectable, true);
+    mBackgroundObject->setFlag(QGraphicsItem::ItemIsMovable, true);
+    mBackgroundObject->setAcceptedMouseButtons(Qt::LeftButton);
+
+    // Item zLayer and Layer Type should be set by the caller of this function, as
+    // it may depend on the object type, where it was before, etc.
+
+    mBackgroundObject = 0;
+}
+
 QRectF UBGraphicsScene::normalizedSceneRect(qreal ratio)
 {
 

src/domain/UBGraphicsScene.h

@@ -174,6 +174,7 @@ class UBGraphicsScene: public UBCoreGraphicsScene, public UBItem
         void addGroup(UBGraphicsGroupContainerItem *groupItem);
 
         QGraphicsItem* setAsBackgroundObject(QGraphicsItem* item, bool pAdaptTransformation = false, bool expand = false);
+        void unsetBackgroundObject();
 
         QGraphicsItem* backgroundObject() const
         {