commands.cpp Example File

/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** 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 https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QtWidgets>
#include "commands.h"
#include "diagramitem.h"
MoveCommand::MoveCommand(DiagramItem *diagramItem, const QPointF &oldPos,
                 QUndoCommand *parent)
    : QUndoCommand(parent)
{
    myDiagramItem = diagramItem;
    newPos = diagramItem->pos();
    myOldPos = oldPos;
}
bool MoveCommand::mergeWith(const QUndoCommand *command)
{
    const MoveCommand *moveCommand = static_cast<const MoveCommand *>(command);
    DiagramItem *item = moveCommand->myDiagramItem;
    if (myDiagramItem != item)
    return false;
    newPos = item->pos();
    setText(QObject::tr("Move %1")
        .arg(createCommandString(myDiagramItem, newPos)));
    return true;
}
void MoveCommand::undo()
{
    myDiagramItem->setPos(myOldPos);
    myDiagramItem->scene()->update();
    setText(QObject::tr("Move %1")
        .arg(createCommandString(myDiagramItem, newPos)));
}
void MoveCommand::redo()
{
    myDiagramItem->setPos(newPos);
    setText(QObject::tr("Move %1")
        .arg(createCommandString(myDiagramItem, newPos)));
}
DeleteCommand::DeleteCommand(QGraphicsScene *scene, QUndoCommand *parent)
    : QUndoCommand(parent)
{
    myGraphicsScene = scene;
    QList<QGraphicsItem *> list = myGraphicsScene->selectedItems();
    list.first()->setSelected(false);
    myDiagramItem = static_cast<DiagramItem *>(list.first());
    setText(QObject::tr("Delete %1")
        .arg(createCommandString(myDiagramItem, myDiagramItem->pos())));
}
void DeleteCommand::undo()
{
    myGraphicsScene->addItem(myDiagramItem);
    myGraphicsScene->update();
}
void DeleteCommand::redo()
{
    myGraphicsScene->removeItem(myDiagramItem);
}
AddCommand::AddCommand(DiagramItem::DiagramType addType,
                       QGraphicsScene *scene, QUndoCommand *parent)
    : QUndoCommand(parent)
{
    static int itemCount = 0;
    myGraphicsScene = scene;
    myDiagramItem = new DiagramItem(addType);
    initialPosition = QPointF((itemCount * 15) % int(scene->width()),
                              (itemCount * 15) % int(scene->height()));
    scene->update();
    ++itemCount;
    setText(QObject::tr("Add %1")
        .arg(createCommandString(myDiagramItem, initialPosition)));
}
AddCommand::~AddCommand()
{
    if (!myDiagramItem->scene())
        delete myDiagramItem;
}
void AddCommand::undo()
{
    myGraphicsScene->removeItem(myDiagramItem);
    myGraphicsScene->update();
}
void AddCommand::redo()
{
    myGraphicsScene->addItem(myDiagramItem);
    myDiagramItem->setPos(initialPosition);
    myGraphicsScene->clearSelection();
    myGraphicsScene->update();
}
QString createCommandString(DiagramItem *item, const QPointF &pos)
{
    return QObject::tr("%1 at (%2, %3)")
        .arg(item->diagramType() == DiagramItem::Box ? "Box" : "Triangle")
        .arg(pos.x()).arg(pos.y());
}