commands.cpp Example File

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  #include "commands.h"

  static const int setShapeRectCommandId = 1;
  static const int setShapeColorCommandId = 2;

  /******************************************************************************
  ** AddShapeCommand
  */

  AddShapeCommand::AddShapeCommand(Document *doc, const Shape &shape, QUndoCommand *parent)
      : QUndoCommand(parent)
  {
      m_doc = doc;
      m_shape = shape;
  }

  void AddShapeCommand::undo()
  {
      m_doc->deleteShape(m_shapeName);
  }

  void AddShapeCommand::redo()
  {
      // A shape only gets a name when it is inserted into a document
      m_shapeName = m_doc->addShape(m_shape);
      setText(QObject::tr("Add %1").arg(m_shapeName));
  }

  /******************************************************************************
  ** RemoveShapeCommand
  */

  RemoveShapeCommand::RemoveShapeCommand(Document *doc, const QString &shapeName,
                                          QUndoCommand *parent)
      : QUndoCommand(parent)
  {
      setText(QObject::tr("Remove %1").arg(shapeName));
      m_doc = doc;
      m_shape = doc->shape(shapeName);
      m_shapeName = shapeName;
  }

  void RemoveShapeCommand::undo()
  {
      m_shapeName = m_doc->addShape(m_shape);
  }

  void RemoveShapeCommand::redo()
  {
      m_doc->deleteShape(m_shapeName);
  }

  /******************************************************************************
  ** SetShapeColorCommand
  */

  SetShapeColorCommand::SetShapeColorCommand(Document *doc, const QString &shapeName,
                                              const QColor &color, QUndoCommand *parent)
      : QUndoCommand(parent)
  {
      setText(QObject::tr("Set %1's color").arg(shapeName));

      m_doc = doc;
      m_shapeName = shapeName;
      m_oldColor = doc->shape(shapeName).color();
      m_newColor = color;
  }

  void SetShapeColorCommand::undo()
  {
      m_doc->setShapeColor(m_shapeName, m_oldColor);
  }

  void SetShapeColorCommand::redo()
  {
      m_doc->setShapeColor(m_shapeName, m_newColor);
  }

  bool SetShapeColorCommand::mergeWith(const QUndoCommand *command)
  {
      if (command->id() != setShapeColorCommandId)
          return false;

      const SetShapeColorCommand *other = static_cast<const SetShapeColorCommand*>(command);
      if (m_shapeName != other->m_shapeName)
          return false;

      m_newColor = other->m_newColor;
      return true;
  }

  int SetShapeColorCommand::id() const
  {
      return setShapeColorCommandId;
  }

  /******************************************************************************
  ** SetShapeRectCommand
  */

  SetShapeRectCommand::SetShapeRectCommand(Document *doc, const QString &shapeName,
                                              const QRect &rect, QUndoCommand *parent)
      : QUndoCommand(parent)
  {
      setText(QObject::tr("Change %1's geometry").arg(shapeName));

      m_doc = doc;
      m_shapeName = shapeName;
      m_oldRect = doc->shape(shapeName).rect();
      m_newRect = rect;
  }

  void SetShapeRectCommand::undo()
  {
      m_doc->setShapeRect(m_shapeName, m_oldRect);
  }

  void SetShapeRectCommand::redo()
  {
      m_doc->setShapeRect(m_shapeName, m_newRect);
  }

  bool SetShapeRectCommand::mergeWith(const QUndoCommand *command)
  {
      if (command->id() != setShapeRectCommandId)
          return false;

      const SetShapeRectCommand *other = static_cast<const SetShapeRectCommand*>(command);
      if (m_shapeName != other->m_shapeName)
          return false;

      m_newRect = other->m_newRect;
      return true;
  }

  int SetShapeRectCommand::id() const
  {
      return setShapeRectCommandId;
  }