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;
 }