Qt 4.0: cannonfield.cpp Example File (tutorial/t10/cannonfield.cpp)

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# cannonfield.cpp Example File
tutorial/t10/cannonfield.cpp

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        **
        ** Copyright (C) 2005-2005 Trolltech AS. All rights reserved.
        **
        ** This file is part of the documentation of the Qt Toolkit.
        **
        ** This file may be used under the terms of the GNU General Public
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    ** and appearing in the file LICENSE.GPL included in the packaging of
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        **
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        ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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        /****************************************************************
        **
        ** Implementation CannonField class, Qt tutorial 10
        **
        ****************************************************************/

        #include <QPaintEvent>
        #include <QPainter>

        #include "cannonfield.h"

        CannonField::CannonField(QWidget *parent)
            : QWidget(parent)
        {
            currentAngle = 45;
            currentForce = 0;
            setPalette(QPalette(QColor(250, 250, 200)));
        }

        void CannonField::setAngle(int angle)
        {
            if (angle < 5)
                angle = 5;
            if (angle > 70)
                angle = 70;
            if (currentAngle == angle)
                return;
            currentAngle = angle;
            update(cannonRect());
            emit angleChanged(currentAngle);
        }

        void CannonField::setForce(int force)
        {
            if (force < 0)
                force = 0;
            if (currentForce == force)
                return;
            currentForce = force;
            emit forceChanged(currentForce);
        }

        void CannonField::paintEvent(QPaintEvent * /* event */)
        {
            QPainter painter(this);

            painter.setPen(Qt::NoPen);
            painter.setBrush(Qt::blue);

            painter.translate(0, height());
            painter.drawPie(QRect(-35, -35, 70, 70), 0, 90 * 16);
            painter.rotate(-currentAngle);
            painter.drawRect(QRect(33, -4, 15, 8));
        }

        QRect CannonField::cannonRect() const
        {
            QRect result(0, 0, 50, 50);
            result.moveBottomLeft(rect().bottomLeft());
            return result;
        }