4.14 实例：排积木程序.txt

qt的源代码

class MainWindow : public QMainWindow
 {
     Q_OBJECT
 public:
     MainWindow();
 public slots:
     void itemMoved(DiagramItem *movedDiagram, const QPointF &moveStartPosition);
 private slots:
     void deleteItem();
     void addBox();
     void addTriangle();
     void about();
     void itemMenuAboutToShow();
     void itemMenuAboutToHide();
 private:
     void createActions();
     void createMenus();
     void createUndoView();
     QAction *deleteAction;
     QAction *addBoxAction;
     QAction *addTriangleAction;
     QAction *undoAction;
     QAction *redoAction;
     QAction *exitAction;
     QAction *aboutAction;
     QMenu *fileMenu;
     QMenu *editMenu;
     QMenu *itemMenu;
     QMenu *helpMenu;
     DiagramScene *diagramScene;
     QUndoStack *undoStack;
     QUndoView *undoView;
 };
 MainWindow::MainWindow()
 {
     undoStack = new QUndoStack();
     createActions();
     createMenus();
     connect(undoStack, SIGNAL(canRedoChanged(bool)),
             redoAction, SLOT(setEnabled(bool)));
     connect(undoStack, SIGNAL(canUndoChanged(bool)),
             undoAction, SLOT(setEnabled(bool)));
     createUndoView();
     diagramScene = new DiagramScene();
     QBrush pixmapBrush(QPixmap(":/images/cross.png").scaled(30, 30));
     diagramScene->setBackgroundBrush(pixmapBrush);
     diagramScene->setSceneRect(QRect(0, 0, 500, 500));
     connect(diagramScene, SIGNAL(itemMoved(DiagramItem *, const QPointF &)),
             this, SLOT(itemMoved(DiagramItem *, const QPointF &)));
     setWindowTitle("Undo Framework");
     QGraphicsView *view = new QGraphicsView(diagramScene);
     setCentralWidget(view);
     resize(700, 500);
 } 
void MainWindow::createUndoView()
 {
     undoView = new QUndoView(undoStack);
     undoView->setWindowTitle(tr("Command List"));
     undoView->show();
     undoView->setAttribute(Qt::WA_QuitOnClose, false);
 } 
void MainWindow::createActions()
 {
     deleteAction = new QAction(tr("&Delete Item"), this);
     deleteAction->setShortcut(tr("Del"));
     connect(deleteAction, SIGNAL(triggered()), this, SLOT(deleteItem()));
     ...
     undoAction = new QAction(tr("&Undo"), this);
     undoAction->setShortcut(tr("Ctrl+Z"));
     undoAction->setEnabled(false);
     connect(undoAction, SIGNAL(triggered()), undoStack, SLOT(undo()));
     redoAction = new QAction(tr("&Redo"), this);
     QList<QKeySequence> redoShortcuts;
     redoShortcuts << tr("Ctrl+Y") << tr("Shift+Ctrl+Z");
     redoAction->setShortcuts(redoShortcuts);
redoAction->setEnabled(false);
     connect(redoAction, SIGNAL(triggered()), undoStack, SLOT(redo())); 
void MainWindow::createMenus()
 {
     ...
     editMenu = menuBar()->addMenu(tr("&Edit"));
     editMenu->addAction(undoAction);
     editMenu->addAction(redoAction);
     editMenu->addSeparator();
     editMenu->addAction(deleteAction);
     connect(editMenu, SIGNAL(aboutToShow()),
             this, SLOT(itemMenuAboutToShow()));
     connect(editMenu, SIGNAL(aboutToHide()),
             this, SLOT(itemMenuAboutToHide()));
     ...
 } 
 void MainWindow::itemMoved(DiagramItem *movedItem,
                            const QPointF &oldPosition)
 {
     undoStack->push(new MoveCommand(movedItem, oldPosition));
 } 
void MainWindow::itemMenuAboutToHide()
 {
     deleteAction->setEnabled(true);
 }
 void MainWindow::itemMenuAboutToShow()
 {
     undoAction->setText(tr("Undo ") + undoStack->undoText());
     redoAction->setText(tr("Redo ") + undoStack->redoText());
     deleteAction->setEnabled(!diagramScene->selectedItems().isEmpty());
 } 
 void MainWindow::addBox()
 {
     QUndoCommand *addCommand = new AddCommand(DiagramItem::Box, diagramScene);
     undoStack->push(addCommand);
 } 
 void MainWindow::addTriangle()
 {
     QUndoCommand *addCommand = new AddCommand(DiagramItem::Triangle,diagramScene);
     undoStack->push(addCommand);
 } 
void MainWindow::about()
 {
     QMessageBox::about(this, tr("About Undo"),
                        tr("The <b>Undo</b> example demonstrates how to "
                           "use Qt's undo framework."));
 } 
 class AddCommand : public QUndoCommand
 {
 public:
     AddCommand(DiagramItem::DiagramType addType, QGraphicsScene *graphicsScene,
                QUndoCommand *parent = 0);
     void undo();
     void redo();
 private:
     DiagramItem *myDiagramItem;
     QGraphicsScene *myGraphicsScene;
     QPointF initialPosition;
 }; 
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)));
 }
 void AddCommand::undo()
 {
     myGraphicsScene->removeItem(myDiagramItem);
     myGraphicsScene->update();
 } 
class DeleteCommand : public QUndoCommand
 {
 public:
     DeleteCommand(QGraphicsScene *graphicsScene, QUndoCommand *parent = 0);
     void undo();
     void redo();
 private:
     DiagramItem *myDiagramItem;
     QGraphicsScene *myGraphicsScene;
 }; 
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);
 } 
class MoveCommand : public QUndoCommand
 {
 public:
     enum { Id = 1234 };
     MoveCommand(DiagramItem *diagramItem, const QPointF &oldPos,
                 QUndoCommand *parent = 0);
     void undo();
     void redo();
     bool mergeWith(const QUndoCommand *command);
     int id() const { return Id; }
 private:
     DiagramItem *myDiagramItem;
     QPointF myOldPos;
     QPointF newPos;
 }; 
 MoveCommand::MoveCommand(DiagramItem *diagramItem, const QPointF &oldPos,
                  QUndoCommand *parent)
     : QUndoCommand(parent)
 {
     myDiagramItem = diagramItem;
     newPos = diagramItem->pos();
     myOldPos = oldPos;
 } 
 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)));
 } 
 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;
 } 
class DiagramScene : public QGraphicsScene
 {
     Q_OBJECT
 public:
     DiagramScene(QObject *parent = 0);
 signals:
     void itemMoved(DiagramItem *movedItem, const QPointF &movedFromPosition);
 protected:
     void mousePressEvent(QGraphicsSceneMouseEvent *event);
     void mouseReleaseEvent(QGraphicsSceneMouseEvent *event);
 private:
     QGraphicsItem *movingItem;
     QPointF oldPos;
 }; 
 int main(int argv, char *args[])
 {
     Q_INIT_RESOURCE(undoframework);
     QApplication app(argv, args);
     MainWindow mainWindow;
     mainWindow.show();
     return app.exec();
 }