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renderarea.cpp Example File
^{painting/basicdrawing/renderarea.cpp}

    /****************************************************************************
    **
    ** Copyright (C) 2005-2006 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
    ** License version 2.0 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 GNU
    ** General Public Licensing requirements will be met:
    ** http://www.trolltech.com/products/qt/opensource.html
    **
    ** If you are unsure which license is appropriate for your use, please
    ** review the following information:
    ** http://www.trolltech.com/products/qt/licensing.html or contact the
    ** sales department at sales@trolltech.com.
    **
    ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
    ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
    **
    ****************************************************************************/

    #include <QtGui>

    #include "renderarea.h"

    RenderArea::RenderArea(QWidget *parent)
        : QWidget(parent)
    {
        shape = Polygon;
        antialiased = false;
        pixmap.load(":/images/qt-logo.png");

        setBackgroundRole(QPalette::Base);
    }

    QSize RenderArea::minimumSizeHint() const
    {
        return QSize(100, 100);
    }

    QSize RenderArea::sizeHint() const
    {
        return QSize(400, 200);
    }

    void RenderArea::setShape(Shape shape)
    {
        this->shape = shape;
        update();
    }

    void RenderArea::setPen(const QPen &pen)
    {
        this->pen = pen;
        update();
    }

    void RenderArea::setBrush(const QBrush &brush)
    {
        this->brush = brush;
        update();
    }

    void RenderArea::setAntialiased(bool antialiased)
    {
        this->antialiased = antialiased;
        update();
    }

    void RenderArea::setTransformed(bool transformed)
    {
        this->transformed = transformed;
        update();
    }

    void RenderArea::paintEvent(QPaintEvent *)
    {
        static const QPoint points[4] = {
            QPoint(10, 80),
            QPoint(20, 10),
            QPoint(80, 30),
            QPoint(90, 70)
        };

        QRect rect(10, 20, 80, 60);

        QPainterPath path;
        path.moveTo(20, 80);
        path.lineTo(20, 30);
        path.cubicTo(80, 0, 50, 50, 80, 80);

        int startAngle = 30 * 16;
        int arcLength = 120 * 16;

        QPainter painter(this);
        painter.setPen(pen);
        painter.setBrush(brush);
        if (antialiased)
            painter.setRenderHint(QPainter::Antialiasing);

        for (int x = 0; x < width(); x += 100) {
            for (int y = 0; y < height(); y += 100) {
                painter.save();
                painter.translate(x, y);
                if (transformed) {
                    painter.translate(50, 50);
                    painter.rotate(60.0);
                    painter.scale(0.6, 0.9);
                    painter.translate(-50, -50);
                }

                switch (shape) {
                case Line:
                    painter.drawLine(rect.bottomLeft(), rect.topRight());
                    break;
                case Points:
                    painter.drawPoints(points, 4);
                    break;
                case Polyline:
                    painter.drawPolyline(points, 4);
                    break;
                case Polygon:
                    painter.drawPolygon(points, 4);
                    break;
                case Rect:
                    painter.drawRect(rect);
                    break;
                case RoundRect:
                    painter.drawRoundRect(rect);
                    break;
                case Ellipse:
                    painter.drawEllipse(rect);
                    break;
                case Arc:
                    painter.drawArc(rect, startAngle, arcLength);
                    break;
                case Chord:
                    painter.drawChord(rect, startAngle, arcLength);
                    break;
                case Pie:
                    painter.drawPie(rect, startAngle, arcLength);
                    break;
                case Path:
                    painter.drawPath(path);
                    break;
                case Text:
                    painter.drawText(rect, Qt::AlignCenter, tr("Qt by\nTrolltech"));
                    break;
                case Pixmap:
                    painter.drawPixmap(10, 10, pixmap);
                }
                painter.restore();
            }
        }
    }