QPainter 基础绘图

调用QPainter的接口来绘制一些基本的图形

头文件：

 #include <QMainWindow>
 #include <QPainter>

 namespace Ui {
 class MainWindow;
 }

 class MainWindow : public QMainWindow
 {
     Q_OBJECT

 public:
     explicit MainWindow(QWidget *parent = );
     ~MainWindow();

 private:
     void paintEvent(QPaintEvent *event);

 private:
     Ui::MainWindow *ui;
     int            m_type;
 };

源文件：

 #include <QRegExp>
 #include <QPixmap>
 #include "mainwindow.h"
 #include "ui_mainwindow.h"

 MainWindow::MainWindow(QWidget *parent) :
     QMainWindow(parent),
     ui(new Ui::MainWindow),
     m_type()
 {
     ui->setupUi(this);
 }

 MainWindow::~MainWindow()
 {
     delete ui;
 }

 void MainWindow::paintEvent(QPaintEvent *event)
 {
     Q_UNUSED(event)
     QPainter painter(this);

     if(m_type == ) // 绘制文本
     {
         painter.setPen(Qt::blue);
         QFont font;
         font.setFamily("Microsoft YaHei");
         font.setPointSize();
         font.setItalic(true);
         font.setBold(true);
         painter.setFont(font);
         painter.drawText(rect(), Qt::AlignCenter, QString::fromLocal8Bit("Qt"));
     }
     else if(m_type == ) // 绘制直线
     {
         painter.setRenderHint(QPainter::Antialiasing, true);
         painter.setPen(Qt::blue);
         painter.drawLine(QPointF(, height()), QPointF(width() / , height() / ));
     }
     else if(m_type == ) // 绘制矩形
     {
         painter.setRenderHint(QPainter::Antialiasing, true);
         painter.setPen(QPen(Qt::blue, ));
         painter.setBrush(Qt::green);
         painter.drawRect(, , , );
     }
     else if(m_type == ) // 绘制弧线
     {
         QRectF rect(90.0, 90.0, 80.0, 90.0);
         int startAngle =  * ;
         int spanAngle =  * ;
         painter.setRenderHint(QPainter::Antialiasing, true);
         painter.setPen(QPen(Qt::blue, ));
         painter.drawArc(rect, startAngle, spanAngle);

     }
     else if(m_type == ) // 绘制椭圆，绘制圆
     {
         painter.setRenderHint(QPainter::Antialiasing, true);
         painter.setPen(QPen(Qt::blue, ));
         painter.drawEllipse(QPointF(, ), , );
         painter.setBrush(Qt::green);
         painter.drawEllipse(QPointF(, ), , );
     }
     else if(m_type == ) // 绘制多边形
     {
         painter.setRenderHint(QPainter::Antialiasing, true);
         painter.setPen(Qt::blue);
         static const QPointF points[] = {QPointF(, ), QPointF(, ), QPointF(, ), QPointF(, ), QPointF(, ), QPointF(, )};
         painter.drawPolygon(points, );
     }
     else if(m_type == ) // 绘制图片
     {
         painter.setRenderHint(QPainter::Antialiasing, true);
         painter.drawPixmap(rect(), QPixmap(":/images/pic.png"));
     }
     else if(m_type == ) // 绘制圆角矩形
     {
         painter.setRenderHint(QPainter::Antialiasing, true);
         painter.setPen(QPen(Qt::blue,,Qt::SolidLine));
         painter.drawRoundRect(,,,,,);
     }
     else if(m_type == ) // 绘制扇形
     {
         painter.setRenderHint(QPainter::Antialiasing, true);
         painter.setPen(QPen(Qt::green,,Qt::SolidLine));
         painter.drawPie(,,,,,);
     }
     else if(m_type == ) // 绘制弦
     {
         painter.setRenderHint(QPainter::Antialiasing, true);
         painter.setPen(QPen(Qt::green,,Qt::SolidLine));
         painter.drawChord(,,,,,);
     }
 }