调用QPainter的接口来绘制一些基本的图形
头文件：
1 #include2 #include 3 4 namespace Ui { 5 class MainWindow; 6 } 7 8 class MainWindow : public QMainWindow 9 {10 Q_OBJECT11 12 public:13 explicit MainWindow(QWidget *parent = 0);14 ~MainWindow();15 16 private:17 void paintEvent(QPaintEvent *event);18 19 private:20 Ui::MainWindow *ui;21 int m_type;22 };
源文件：
1 #include2 #include 3 #include "mainwindow.h" 4 #include "ui_mainwindow.h" 5 6 MainWindow::MainWindow(QWidget *parent) : 7 QMainWindow(parent), 8 ui(new Ui::MainWindow), 9 m_type(1)10 {11 ui->setupUi(this);12 }13 14 MainWindow::~MainWindow()15 {16 delete ui;17 }18 19 void MainWindow::paintEvent(QPaintEvent *event)20 {21 Q_UNUSED(event)22 QPainter painter(this);23 24 if(m_type == 1) // 绘制文本25 {26 painter.setPen(Qt::blue);27 QFont font;28 font.setFamily("Microsoft YaHei");29 font.setPointSize(50);30 font.setItalic(true);31 font.setBold(true);32 painter.setFont(font);33 painter.drawText(rect(), Qt::AlignCenter, QString::fromLocal8Bit("Qt"));34 }35 else if(m_type == 2) // 绘制直线36 {37 painter.setRenderHint(QPainter::Antialiasing, true);38 painter.setPen(Qt::blue);39 painter.drawLine(QPointF(0, height()), QPointF(width() / 2, height() / 2));40 }41 else if(m_type == 3) // 绘制矩形42 {43 painter.setRenderHint(QPainter::Antialiasing, true);44 painter.setPen(QPen(Qt::blue, 2));45 painter.setBrush(Qt::green);46 painter.drawRect(50, 50, 160, 100);47 }48 else if(m_type == 4) // 绘制弧线49 {50 QRectF rect(90.0, 90.0, 80.0, 90.0);51 int startAngle = 30 * 16;52 int spanAngle = 120 * 16;53 painter.setRenderHint(QPainter::Antialiasing, true);54 painter.setPen(QPen(Qt::blue, 2));55 painter.drawArc(rect, startAngle, spanAngle);56 57 }58 else if(m_type == 5) // 绘制椭圆，绘制圆59 {60 painter.setRenderHint(QPainter::Antialiasing, true);61 painter.setPen(QPen(Qt::blue, 2));62 painter.drawEllipse(QPointF(120, 160), 50, 20);63 painter.setBrush(Qt::green);64 painter.drawEllipse(QPointF(120, 140), 40, 40);65 }66 else if(m_type == 6) // 绘制多边形67 {68 painter.setRenderHint(QPainter::Antialiasing, true);69 painter.setPen(Qt::blue);70 static const QPointF points[6] = {QPointF(10, 40), QPointF(60, 190), QPointF(110, 160), QPointF(220, 180), QPointF(270, 120), QPointF(220, 280)};71 painter.drawPolygon(points, 6);72 }73 else if(m_type == 7) // 绘制图片74 {75 painter.setRenderHint(QPainter::Antialiasing, true);76 painter.drawPixmap(rect(), QPixmap(":/images/pic.png"));77 }78 else if(m_type == 8) // 绘制圆角矩形79 {80 painter.setRenderHint(QPainter::Antialiasing, true);81 painter.setPen(QPen(Qt::blue,2,Qt::SolidLine));82 painter.drawRoundRect(80,80,210,160,50,50);83 }84 else if(m_type == 9) // 绘制扇形85 {86 painter.setRenderHint(QPainter::Antialiasing, true);87 painter.setPen(QPen(Qt::green,2,Qt::SolidLine));88 painter.drawPie(80,80,210,160,0,500);89 }90 else if(m_type == 10) // 绘制弦91 {92 painter.setRenderHint(QPainter::Antialiasing, true);93 painter.setPen(QPen(Qt::green,2,Qt::SolidLine));94 painter.drawChord(80,80,210,160,500,1000);95 }96 }