mainwindow.cpp Example File
^{demos/undo/mainwindow.cpp}

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 #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"));
 }