Qt 绘制文本、直线、矩形、椭圆、多边形_qt 鼠标在图像上画多边形并编辑

绘制文本、直线、矩形、椭圆、多边形小例子

void MainWindow::paintEvent(QPaintEvent *event)
{
    Q_UNUSED(event)

    QRect rectWnd = this->rect();
    // 绘制文字
    QPainter painter(this);
    // 设置画笔颜色
    painter.setPen(QPen(Qt::black, 4, Qt::DashDotLine, Qt::RoundCap));

    //设置字体
    QFont font;
    font.setFamily("楷体");
    font.setPointSize(50);  // 字体大小
    font.setItalic(true);   // 斜体
    font.setBold(true);     // 粗体

    // 设置反走样
    painter.setRenderHint(QPainter::Antialiasing);

    // 设置字体
    painter.setFont(font);

    // 绘制文本
    painter.drawText(0, 0, rectWnd.width() / 4, rectWnd.height() / 4, Qt::AlignCenter,  "我们");

    // 绘制直线
    painter.drawLine(rectWnd.width() / 4, rectWnd.height() / 4, rectWnd.width() / 2,  rectWnd.height() / 2);

    // 绘制矩形

    painter.setBrush(QBrush(QColor(0, 255, 0)));
    painter.drawRect(10, rectWnd.width() / 4, rectWnd.width() / 8, rectWnd.height() / 4);

    // 绘制椭圆
    painter.drawEllipse(rectWnd.width() / 2,  rectWnd.height() / 2, rectWnd.width() / 4, rectWnd.width() / 8);

    // 绘制多边形
    painter.setBrush(Qt::NoBrush);
    const static QPoint polygon[5] = {QPoint(100,90), QPoint(100,120), QPoint(220,200), QPoint(430,190), QPoint(620,90)};
    painter.drawPolygon(polygon, 5);
}
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