Qt 5.11 | Qt Widgets | Undo Framework Example | mainwindow.cpp Example File

Qt 5.11.3 Reference Documentation

# mainwindow.cpp Example File

tools/undoframework/mainwindow.cpp

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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."));
      }