Qt 5.11 | Qt Widgets | Undo Framework Example | commands.cpp Example File

Qt 5.11.3 Reference Documentation

# commands.cpp Example File

tools/undoframework/commands.cpp

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      #include <QtWidgets>

      #include "commands.h"
      #include "diagramitem.h"

      MoveCommand::MoveCommand(DiagramItem *diagramItem, const QPointF &oldPos,
                       QUndoCommand *parent)
          : QUndoCommand(parent)
      {
          myDiagramItem = diagramItem;
          newPos = diagramItem->pos();
          myOldPos = oldPos;
      }

      bool MoveCommand::mergeWith(const QUndoCommand *command)
      {
          const MoveCommand *moveCommand = static_cast<const MoveCommand *>(command);
          DiagramItem *item = moveCommand->myDiagramItem;

          if (myDiagramItem != item)
          return false;

          newPos = item->pos();
          setText(QObject::tr("Move %1")
              .arg(createCommandString(myDiagramItem, newPos)));

          return true;
      }

      void MoveCommand::undo()
      {
          myDiagramItem->setPos(myOldPos);
          myDiagramItem->scene()->update();
          setText(QObject::tr("Move %1")
              .arg(createCommandString(myDiagramItem, newPos)));
      }

      void MoveCommand::redo()
      {
          myDiagramItem->setPos(newPos);
          setText(QObject::tr("Move %1")
              .arg(createCommandString(myDiagramItem, newPos)));
      }

      DeleteCommand::DeleteCommand(QGraphicsScene *scene, QUndoCommand *parent)
          : QUndoCommand(parent)
      {
          myGraphicsScene = scene;
          QList<QGraphicsItem *> list = myGraphicsScene->selectedItems();
          list.first()->setSelected(false);
          myDiagramItem = static_cast<DiagramItem *>(list.first());
          setText(QObject::tr("Delete %1")
              .arg(createCommandString(myDiagramItem, myDiagramItem->pos())));
      }

      void DeleteCommand::undo()
      {
          myGraphicsScene->addItem(myDiagramItem);
          myGraphicsScene->update();
      }

      void DeleteCommand::redo()
      {
          myGraphicsScene->removeItem(myDiagramItem);
      }

      AddCommand::AddCommand(DiagramItem::DiagramType addType,
                             QGraphicsScene *scene, QUndoCommand *parent)
          : QUndoCommand(parent)
      {
          static int itemCount = 0;

          myGraphicsScene = scene;
          myDiagramItem = new DiagramItem(addType);
          initialPosition = QPointF((itemCount * 15) % int(scene->width()),
                                    (itemCount * 15) % int(scene->height()));
          scene->update();
          ++itemCount;
          setText(QObject::tr("Add %1")
              .arg(createCommandString(myDiagramItem, initialPosition)));
      }

      AddCommand::~AddCommand()
      {
          if (!myDiagramItem->scene())
              delete myDiagramItem;
      }

      void AddCommand::undo()
      {
          myGraphicsScene->removeItem(myDiagramItem);
          myGraphicsScene->update();
      }

      void AddCommand::redo()
      {
          myGraphicsScene->addItem(myDiagramItem);
          myDiagramItem->setPos(initialPosition);
          myGraphicsScene->clearSelection();
          myGraphicsScene->update();
      }

      QString createCommandString(DiagramItem *item, const QPointF &pos)
      {
          return QObject::tr("%1 at (%2, %3)")
              .arg(item->diagramType() == DiagramItem::Box ? "Box" : "Triangle")
              .arg(pos.x()).arg(pos.y());
      }