坐标转换

QTransform被指定用来做为坐标系统中的2D转换用到的类。

void CombinedTransformation::paintEvent(QPaintEvent *){    QPainter painter(this);    painter.setPen(QPen(Qt::blue, 1, Qt::DashLine));    painter.drawRect(0, 0, 100, 100);    QTransform transform;    transform.translate(50, 50);    transform.rotate(45);    transform.scale(0.5, 1.0);    painter.setTransform(transform);    painter.setFont(QFont("Helvetica", 24));    painter.setPen(QPen(Qt::black, 1));    painter.drawText(20, 10, "QTransform");