displaywidget.cpp Example File

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 #include <QtGui>
 #include "displaywidget.h"

 DisplayWidget::DisplayWidget(QWidget *parent)
     : QWidget(parent)
 {
     QPainterPath car;
     QPainterPath house;

     QFile file(":resources/shapes.dat");
     file.open(QFile::ReadOnly);
     QDataStream stream(&file);
     stream >> car >> house >> tree >> moon;
     file.close();

     shapeMap[Car] = car;
     shapeMap[House] = house;

     background = Sky;
     shapeColor = Qt::darkYellow;
     shape = House;
 }

 void DisplayWidget::paintEvent(QPaintEvent * /* event */)
 {
     QPainter painter;
     painter.begin(this);
     painter.setRenderHint(QPainter::Antialiasing);
     paint(painter);
     painter.end();
 }

 void DisplayWidget::paint(QPainter &painter)
 {
     painter.setClipRect(QRect(0, 0, 200, 200));
     painter.setPen(Qt::NoPen);

     switch (background) {
     case Sky:
     default:
         painter.fillRect(QRect(0, 0, 200, 200), Qt::darkBlue);
         painter.translate(145, 10);
         painter.setBrush(Qt::white);
         painter.drawPath(moon);
         painter.translate(-145, -10);
         break;
     case Trees:
     {
         painter.fillRect(QRect(0, 0, 200, 200), Qt::darkGreen);
         painter.setBrush(Qt::green);
         painter.setPen(Qt::black);
         for (int y = -55, row = 0; y < 200; y += 50, ++row) {
             int xs;
             if (row == 2 || row == 3)
                 xs = 150;
             else
                 xs = 50;
             for (int x = 0; x < 200; x += xs) {
                 painter.save();
                 painter.translate(x, y);
                 painter.drawPath(tree);
                 painter.restore();
             }
         }
         break;
     }
     case Road:
         painter.fillRect(QRect(0, 0, 200, 200), Qt::gray);
         painter.setPen(QPen(Qt::white, 4, Qt::DashLine));
         painter.drawLine(QLine(0, 35, 200, 35));
         painter.drawLine(QLine(0, 165, 200, 165));
         break;
     }

     painter.setBrush(shapeColor);
     painter.setPen(Qt::black);
     painter.translate(100, 100);
     painter.drawPath(shapeMap[shape]);
 }

 QColor DisplayWidget::color() const
 {
     return shapeColor;
 }

 void DisplayWidget::setBackground(Background background)
 {
     this->background = background;
     update();
 }

 void DisplayWidget::setColor(const QColor &color)
 {
     this->shapeColor = color;
     update();
 }

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