- Qt 5.5
- Qt Widgets
- Undo Framework
- mainwindow.cpp Example File
- Qt 5.5.1 Reference Documentation

# mainwindow.cpp Example File

tools/undo/mainwindow.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the demonstration applications of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:LGPL21$
    ** Commercial License Usage
    ** Licensees holding valid commercial Qt licenses may use this file in
    ** accordance with the commercial license agreement provided with the
    ** Software or, alternatively, in accordance with the terms contained in
    ** a written agreement between you and The Qt Company. For licensing terms
    ** and conditions see http://www.qt.io/terms-conditions. For further
    ** information use the contact form at http://www.qt.io/contact-us.
    **
    ** GNU Lesser General Public License Usage
    ** Alternatively, this file may be used under the terms of the GNU Lesser
    ** General Public License version 2.1 or version 3 as published by the Free
    ** Software Foundation and appearing in the file LICENSE.LGPLv21 and
    ** LICENSE.LGPLv3 included in the packaging of this file. Please review the
    ** following information to ensure the GNU Lesser General Public License
    ** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
    ** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
    **
    ** As a special exception, The Qt Company gives you certain additional
    ** rights. These rights are described in The Qt Company LGPL Exception
    ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
    **
    ** $QT_END_LICENSE$
    **
    ****************************************************************************/

    #include <QUndoGroup>
    #include <QUndoStack>
    #include <QFileDialog>
    #include <QMessageBox>
    #include <QTextStream>
    #include <QToolButton>
    #include "document.h"
    #include "mainwindow.h"
    #include "commands.h"

    MainWindow::MainWindow(QWidget *parent)
        : QMainWindow(parent)
    {
        setupUi(this);

        QWidget *w = documentTabs->widget(0);
        documentTabs->removeTab(0);
        delete w;

        connect(actionOpen, SIGNAL(triggered()), this, SLOT(openDocument()));
        connect(actionClose, SIGNAL(triggered()), this, SLOT(closeDocument()));
        connect(actionNew, SIGNAL(triggered()), this, SLOT(newDocument()));
        connect(actionSave, SIGNAL(triggered()), this, SLOT(saveDocument()));
        connect(actionExit, SIGNAL(triggered()), this, SLOT(close()));
        connect(actionRed, SIGNAL(triggered()), this, SLOT(setShapeColor()));
        connect(actionGreen, SIGNAL(triggered()), this, SLOT(setShapeColor()));
        connect(actionBlue, SIGNAL(triggered()), this, SLOT(setShapeColor()));
        connect(actionAddCircle, SIGNAL(triggered()), this, SLOT(addShape()));
        connect(actionAddRectangle, SIGNAL(triggered()), this, SLOT(addShape()));
        connect(actionAddTriangle, SIGNAL(triggered()), this, SLOT(addShape()));
        connect(actionRemoveShape, SIGNAL(triggered()), this, SLOT(removeShape()));
        connect(actionAddRobot, SIGNAL(triggered()), this, SLOT(addRobot()));
        connect(actionAddSnowman, SIGNAL(triggered()), this, SLOT(addSnowman()));
        connect(actionAbout, SIGNAL(triggered()), this, SLOT(about()));
        connect(actionAboutQt, SIGNAL(triggered()), this, SLOT(aboutQt()));

        connect(undoLimit, SIGNAL(valueChanged(int)), this, SLOT(updateActions()));
        connect(documentTabs, SIGNAL(currentChanged(int)), this, SLOT(updateActions()));

        actionOpen->setShortcut(QString("Ctrl+O"));
        actionClose->setShortcut(QString("Ctrl+W"));
        actionNew->setShortcut(QString("Ctrl+N"));
        actionSave->setShortcut(QString("Ctrl+S"));
        actionExit->setShortcut(QString("Ctrl+Q"));
        actionRemoveShape->setShortcut(QString("Del"));
        actionRed->setShortcut(QString("Alt+R"));
        actionGreen->setShortcut(QString("Alt+G"));
        actionBlue->setShortcut(QString("Alt+B"));
        actionAddCircle->setShortcut(QString("Alt+C"));
        actionAddRectangle->setShortcut(QString("Alt+L"));
        actionAddTriangle->setShortcut(QString("Alt+T"));

        m_undoGroup = new QUndoGroup(this);
        undoView->setGroup(m_undoGroup);
        undoView->setCleanIcon(QIcon(":/icons/ok.png"));

        QAction *undoAction = m_undoGroup->createUndoAction(this);
        QAction *redoAction = m_undoGroup->createRedoAction(this);
        undoAction->setIcon(QIcon(":/icons/undo.png"));
        redoAction->setIcon(QIcon(":/icons/redo.png"));
        menuShape->insertAction(menuShape->actions().at(0), undoAction);
        menuShape->insertAction(undoAction, redoAction);

        toolBar->addAction(undoAction);
        toolBar->addAction(redoAction);

        newDocument();
        updateActions();
    };

    void MainWindow::updateActions()
    {
        Document *doc = currentDocument();
        m_undoGroup->setActiveStack(doc == 0 ? 0 : doc->undoStack());
        QString shapeName = doc == 0 ? QString() : doc->currentShapeName();

        actionAddRobot->setEnabled(doc != 0);
        actionAddSnowman->setEnabled(doc != 0);
        actionAddCircle->setEnabled(doc != 0);
        actionAddRectangle->setEnabled(doc != 0);
        actionAddTriangle->setEnabled(doc != 0);
        actionClose->setEnabled(doc != 0);
        actionSave->setEnabled(doc != 0 && !doc->undoStack()->isClean());
        undoLimit->setEnabled(doc != 0 && doc->undoStack()->count() == 0);

        if (shapeName.isEmpty()) {
            actionRed->setEnabled(false);
            actionGreen->setEnabled(false);
            actionBlue->setEnabled(false);
            actionRemoveShape->setEnabled(false);
        } else {
            Shape shape = doc->shape(shapeName);
            actionRed->setEnabled(shape.color() != Qt::red);
            actionGreen->setEnabled(shape.color() != Qt::green);
            actionBlue->setEnabled(shape.color() != Qt::blue);
            actionRemoveShape->setEnabled(true);
        }

        if (doc != 0) {
            int index = documentTabs->indexOf(doc);
            Q_ASSERT(index != -1);
            static const QIcon unsavedIcon(":/icons/filesave.png");
            documentTabs->setTabIcon(index, doc->undoStack()->isClean() ? QIcon() : unsavedIcon);

            if (doc->undoStack()->count() == 0)
                doc->undoStack()->setUndoLimit(undoLimit->value());
        }
    }

    void MainWindow::openDocument()
    {
        QString fileName = QFileDialog::getOpenFileName(this);
        if (fileName.isEmpty())
            return;

        QFile file(fileName);
        if (!file.open(QIODevice::ReadOnly)) {
            QMessageBox::warning(this,
                                tr("File error"),
                                tr("Failed to open\n%1").arg(fileName));
            return;
        }
        QTextStream stream(&file);

        Document *doc = new Document();
        if (!doc->load(stream)) {
            QMessageBox::warning(this,
                                tr("Parse error"),
                                tr("Failed to parse\n%1").arg(fileName));
            delete doc;
            return;
        }

        doc->setFileName(fileName);
        addDocument(doc);
    }

    QString MainWindow::fixedWindowTitle(const Document *doc) const
    {
        QString title = doc->fileName();

        if (title.isEmpty())
            title = tr("Unnamed");
        else
            title = QFileInfo(title).fileName();

        QString result;

        for (int i = 0; ; ++i) {
            result = title;
            if (i > 0)
                result += QString::number(i);

            bool unique = true;
            for (int j = 0; j < documentTabs->count(); ++j) {
                const QWidget *widget = documentTabs->widget(j);
                if (widget == doc)
                    continue;
                if (result == documentTabs->tabText(j)) {
                    unique = false;
                    break;
                }
            }

            if (unique)
                break;
        }

        return result;
    }

    void MainWindow::addDocument(Document *doc)
    {
        if (documentTabs->indexOf(doc) != -1)
            return;
        m_undoGroup->addStack(doc->undoStack());
        documentTabs->addTab(doc, fixedWindowTitle(doc));
        connect(doc, SIGNAL(currentShapeChanged(QString)), this, SLOT(updateActions()));
        connect(doc->undoStack(), SIGNAL(indexChanged(int)), this, SLOT(updateActions()));
        connect(doc->undoStack(), SIGNAL(cleanChanged(bool)), this, SLOT(updateActions()));

        setCurrentDocument(doc);
    }

    void MainWindow::setCurrentDocument(Document *doc)
    {
        documentTabs->setCurrentWidget(doc);
    }

    Document *MainWindow::currentDocument() const
    {
        return qobject_cast<Document*>(documentTabs->currentWidget());
    }

    void MainWindow::removeDocument(Document *doc)
    {
        int index = documentTabs->indexOf(doc);
        if (index == -1)
            return;

        documentTabs->removeTab(index);
        m_undoGroup->removeStack(doc->undoStack());
        disconnect(doc, SIGNAL(currentShapeChanged(QString)), this, SLOT(updateActions()));
        disconnect(doc->undoStack(), SIGNAL(indexChanged(int)), this, SLOT(updateActions()));
        disconnect(doc->undoStack(), SIGNAL(cleanChanged(bool)), this, SLOT(updateActions()));

        if (documentTabs->count() == 0) {
            newDocument();
            updateActions();
        }
    }

    void MainWindow::saveDocument()
    {
        Document *doc = currentDocument();
        if (doc == 0)
            return;

        for (;;) {
            QString fileName = doc->fileName();

            if (fileName.isEmpty())
                fileName = QFileDialog::getSaveFileName(this);
            if (fileName.isEmpty())
                break;

            QFile file(fileName);
            if (!file.open(QIODevice::WriteOnly)) {
                QMessageBox::warning(this,
                                    tr("File error"),
                                    tr("Failed to open\n%1").arg(fileName));
                doc->setFileName(QString());
            } else {
                QTextStream stream(&file);
                doc->save(stream);
                doc->setFileName(fileName);

                int index = documentTabs->indexOf(doc);
                Q_ASSERT(index != -1);
                documentTabs->setTabText(index, fixedWindowTitle(doc));

                break;
            }
        }
    }

    void MainWindow::closeDocument()
    {
        Document *doc = currentDocument();
        if (doc == 0)
            return;

        if (!doc->undoStack()->isClean()) {
            int button
                = QMessageBox::warning(this,
                                tr("Unsaved changes"),
                                tr("Would you like to save this document?"),
                                QMessageBox::Yes, QMessageBox::No);
            if (button == QMessageBox::Yes)
                saveDocument();
        }

        removeDocument(doc);
        delete doc;
    }

    void MainWindow::newDocument()
    {
        addDocument(new Document());
    }

    static QColor randomColor()
    {
        int r = (int) (3.0*(rand()/(RAND_MAX + 1.0)));
        switch (r) {
            case 0:
                return Qt::red;
            case 1:
                return Qt::green;
            default:
                break;
        }
        return Qt::blue;
    }

    static QRect randomRect(const QSize &s)
    {
        QSize min = Shape::minSize;

        int left = (int) ((0.0 + s.width() - min.width())*(rand()/(RAND_MAX + 1.0)));
        int top = (int) ((0.0 + s.height() - min.height())*(rand()/(RAND_MAX + 1.0)));
        int width = (int) ((0.0 + s.width() - left - min.width())*(rand()/(RAND_MAX + 1.0))) + min.width();
        int height = (int) ((0.0 + s.height() - top - min.height())*(rand()/(RAND_MAX + 1.0))) + min.height();

        return QRect(left, top, width, height);
    }

    void MainWindow::addShape()
    {
        Document *doc = currentDocument();
        if (doc == 0)
            return;

        Shape::Type type;

        if (sender() == actionAddCircle)
            type = Shape::Circle;
        else if (sender() == actionAddRectangle)
            type = Shape::Rectangle;
        else if (sender() == actionAddTriangle)
            type = Shape::Triangle;
        else return;

        Shape newShape(type, randomColor(), randomRect(doc->size()));
        doc->undoStack()->push(new AddShapeCommand(doc, newShape));
    }

    void MainWindow::removeShape()
    {
        Document *doc = currentDocument();
        if (doc == 0)
            return;

        QString shapeName = doc->currentShapeName();
        if (shapeName.isEmpty())
            return;

        doc->undoStack()->push(new RemoveShapeCommand(doc, shapeName));
    }

    void MainWindow::setShapeColor()
    {
        Document *doc = currentDocument();
        if (doc == 0)
            return;

        QString shapeName = doc->currentShapeName();
        if (shapeName.isEmpty())
            return;

        QColor color;

        if (sender() == actionRed)
            color = Qt::red;
        else if (sender() == actionGreen)
            color = Qt::green;
        else if (sender() == actionBlue)
            color = Qt::blue;
        else
            return;

        if (color == doc->shape(shapeName).color())
            return;

        doc->undoStack()->push(new SetShapeColorCommand(doc, shapeName, color));
    }

    void MainWindow::addSnowman()
    {
        Document *doc = currentDocument();
        if (doc == 0)
            return;

        // Create a macro command using beginMacro() and endMacro()

        doc->undoStack()->beginMacro(tr("Add snowman"));
        doc->undoStack()->push(new AddShapeCommand(doc,
                                Shape(Shape::Circle, Qt::blue, QRect(51, 30, 97, 95))));
        doc->undoStack()->push(new AddShapeCommand(doc,
                                Shape(Shape::Circle, Qt::blue, QRect(27, 123, 150, 133))));
        doc->undoStack()->push(new AddShapeCommand(doc,
                                Shape(Shape::Circle, Qt::blue, QRect(11, 253, 188, 146))));
        doc->undoStack()->endMacro();
    }

    void MainWindow::addRobot()
    {
        Document *doc = currentDocument();
        if (doc == 0)
            return;

        // Compose a macro command by explicitly adding children to a parent command

        QUndoCommand *parent = new QUndoCommand(tr("Add robot"));

        new AddShapeCommand(doc, Shape(Shape::Rectangle, Qt::green, QRect(115, 15, 81, 70)), parent);
        new AddShapeCommand(doc, Shape(Shape::Rectangle, Qt::green, QRect(82, 89, 148, 188)), parent);
        new AddShapeCommand(doc, Shape(Shape::Rectangle, Qt::green, QRect(76, 280, 80, 165)), parent);
        new AddShapeCommand(doc, Shape(Shape::Rectangle, Qt::green, QRect(163, 280, 80, 164)), parent);
        new AddShapeCommand(doc, Shape(Shape::Circle, Qt::blue, QRect(116, 25, 80, 50)), parent);
        new AddShapeCommand(doc, Shape(Shape::Rectangle, Qt::green, QRect(232, 92, 80, 127)), parent);
        new AddShapeCommand(doc, Shape(Shape::Rectangle, Qt::green, QRect(2, 92, 80, 125)), parent);

        doc->undoStack()->push(parent);
    }

    void MainWindow::about()
    {
        QMessageBox::about(this, tr("About Undo"), tr("The Undo demonstration shows how to use the Qt Undo framework."));
    }

    void MainWindow::aboutQt()
    {
        QMessageBox::aboutQt(this, tr("About Qt"));
    }