Qt 4.3: renderarea.cpp Example File (painting/basicdrawing/renderarea.cpp)

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# renderarea.cpp Example File
painting/basicdrawing/renderarea.cpp

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     **
     ** This file is part of the documentation of the Qt Toolkit.
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    ** included in the packaging of this file.  Alternatively you may (at
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     ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
     ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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     #include <QtGui>

     #include "renderarea.h"

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

         setBackgroundRole(QPalette::Base);
         setAutoFillBackground(true);
     }

     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 * /* event */)
     {
         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, true);
             painter.translate(+0.5, +0.5);
         }

         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();
             }
         }

         painter.setPen(palette().dark().color());
         painter.setBrush(Qt::NoBrush);
         painter.drawRect(QRect(0, 0, width() - 1, height() - 1));
     }