撤消操作（undo/redo）

/**************************************************************************** ** ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). ** All rights reserved. ** Contact: Nokia Corporation (qt-info@nokia.com) ** ** This file is part of the examples of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:LGPL$ ** Commercial Usage ** Licensees holding valid Qt Commercial licenses may use this file in ** accordance with the Qt Commercial License Agreement provided with the ** Software or, alternatively, in accordance with the terms contained in ** a written agreement between you and Nokia. ** ** 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 as published by the Free Software ** Foundation and appearing in the file LICENSE.LGPL included in the ** packaging of this file. Please review the following information to ** ensure the GNU Lesser General Public License version 2.1 requirements ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. ** ** In addition, as a special exception, Nokia gives you certain additional ** rights. These rights are described in the Nokia Qt LGPL Exception ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. ** ** GNU General Public License Usage ** Alternatively, this file may be used under the terms of the GNU ** General Public License version 3.0 as published by the Free Software ** Foundation and appearing in the file LICENSE.GPL included in the ** packaging of this file. Please review the following information to ** ensure the GNU General Public License version 3.0 requirements will be ** met: http://www.gnu.org/copyleft/gpl.html. ** ** If you have questions regarding the use of this file, please contact ** Nokia at qt-info@nokia.com. ** $QT_END_LICENSE$ ** ****************************************************************************/ #include <QtGui> #include "mainwindow.h" #include "diagramscene.h" #include "diagramitem.h" #include "commands.h" //! [0] MainWindow::MainWindow() { undoStack = new QUndoStack(); 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); } //! [0] //! [1] void MainWindow::createUndoView() { undoView = new QUndoView(undoStack); undoView->setWindowTitle(tr("Command List")); undoView->show(); undoView->setAttribute(Qt::WA_QuitOnClose, false); } //! [1] //! [2] void MainWindow::createActions() { deleteAction = new QAction(tr("&Delete Item"), this); deleteAction->setShortcut(tr("Del")); connect(deleteAction, SIGNAL(triggered()), this, SLOT(deleteItem())); //! [2] //! [3] //! [3] //! [4] addBoxAction = new QAction(tr("Add &Box"), this); //! [4] 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())); //! [5] undoAction = undoStack->createUndoAction(this, tr("&Undo")); undoAction->setShortcuts(QKeySequence::Undo); redoAction = undoStack->createRedoAction(this, tr("&Redo")); redoAction->setShortcuts(QKeySequence::Redo); //! [5] 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())); } //! [6] void MainWindow::createMenus() { //! [6] fileMenu = menuBar()->addMenu(tr("&File")); fileMenu->addAction(exitAction); //! [7] 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())); //! [7] itemMenu = menuBar()->addMenu(tr("&Item")); itemMenu->addAction(addBoxAction); itemMenu->addAction(addTriangleAction); helpMenu = menuBar()->addMenu(tr("&About")); helpMenu->addAction(aboutAction); //! [8] } //! [8] //! [9] void MainWindow::itemMoved(DiagramItem *movedItem, const QPointF &oldPosition) { undoStack->push(new MoveCommand(movedItem, oldPosition)); } //! [9] //! [10] void MainWindow::deleteItem() { if (diagramScene->selectedItems().isEmpty()) return; QUndoCommand *deleteCommand = new DeleteCommand(diagramScene); undoStack->push(deleteCommand); } //! [10] //! [11] void MainWindow::itemMenuAboutToHide() { deleteAction->setEnabled(true); } //! [11] //! [12] void MainWindow::itemMenuAboutToShow() { deleteAction->setEnabled(!diagramScene->selectedItems().isEmpty()); } //! [12] //! [13] void MainWindow::addBox() { QUndoCommand *addCommand = new AddCommand(DiagramItem::Box, diagramScene); undoStack->push(addCommand); } //! [13] //! [14] void MainWindow::addTriangle() { QUndoCommand *addCommand = new AddCommand(DiagramItem::Triangle, diagramScene); undoStack->push(addCommand); } //! [14] //! [15] void MainWindow::about() { QMessageBox::about(this, tr("About Undo"), tr("The <b>Undo</b> example demonstrates how to " "use Qt's undo framework.")); } //! [15]