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# mainwindow.cpp Example File
tools/undoframework/mainwindow.cpp

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     #include <QtGui>

     #include "mainwindow.h"
     #include "diagramscene.h"
     #include "diagramitem.h"
     #include "commands.h"

     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()));

         addBoxAction = new QAction(tr("Add &Box"), this);
         addBoxAction->setShortcut(tr("Ctrl+O"));
         connect(addBoxAction, SIGNAL(triggered()), this, SLOT(addBox()));

         addTriangleAction = new QAction(tr("Add &Triangle"), this);
         addTriangleAction->setShortcut(tr("Ctrl+T"));
         connect(addTriangleAction, SIGNAL(triggered()), this, SLOT(addTriangle()));

         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()));

         exitAction = new QAction(tr("E&xit"), this);
         exitAction->setShortcut(tr("Ctrl+Q"));
         connect(exitAction, SIGNAL(triggered()), this, SLOT(close()));

         aboutAction = new QAction(tr("&About"), this);
         QList<QKeySequence> aboutShortcuts;
         aboutShortcuts << tr("Ctrl+A") << tr("Ctrl+B");
         aboutAction->setShortcuts(aboutShortcuts);
         connect(aboutAction, SIGNAL(triggered()), this, SLOT(about()));
     }

     void MainWindow::createMenus()
     {
         fileMenu = menuBar()->addMenu(tr("&File"));
         fileMenu->addAction(exitAction);

         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()));

         itemMenu = menuBar()->addMenu(tr("&Item"));
         itemMenu->addAction(addBoxAction);
         itemMenu->addAction(addTriangleAction);

         helpMenu = menuBar()->addMenu(tr("&About"));
         helpMenu->addAction(aboutAction);
     }

     void MainWindow::itemMoved(DiagramItem *movedItem,
                                const QPointF &oldPosition)
     {
         undoStack->push(new MoveCommand(movedItem, oldPosition));
     }

     void MainWindow::deleteItem()
     {
         if (diagramScene->selectedItems().isEmpty())
             return;

         QUndoCommand *deleteCommand = new DeleteCommand(diagramScene);
         undoStack->push(deleteCommand);
     }

     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."));
     }