Qt绘图设备QPixmap

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);

    /* 绘图设备 专门为平台做了显示的优化 */
    QPixmap pixmap(300, 300);
    pixmap.fill(Qt::lightGray);

    QPainter painter(&pixmap);
    painter.setPen(Qt::red);
    painter.drawEllipse(QPoint(100, 100), 50, 50);

    ui->label->setPixmap(pixmap);
}