mainwindow.cpp Example File

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#include <QtWidgets>

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

MainWindow::MainWindow()
{
    undoStack = new QUndoStack(this);

    createActions();
    createMenus();

    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*,QPointF)),
            this, SLOT(itemMoved(DiagramItem*,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 = undoStack->createUndoAction(this, tr("&Undo"));
    undoAction->setShortcuts(QKeySequence::Undo);

    redoAction = undoStack->createRedoAction(this, tr("&Redo"));
    redoAction->setShortcuts(QKeySequence::Redo);

    exitAction = new QAction(tr("E&xit"), this);
    exitAction->setShortcuts(QKeySequence::Quit);
    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()
{
    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."));
}