qt开发（二）: graphic view放大导致text失真的完美解决办法

text变形其实本质是painter被加上scale之后，text也随之改变，解决办法是把这个scale找出来，让他只作用于坐标而不作用于text本身。

void Line::paint(QPainter *painter, const QStyleOptionGraphicsItem *option,

           QWidget *widget){

    painter->setPen(myPen);

    painter->drawLine(myLine);

    if(mark_.isEmpty()==false){

        painter->setPen(QPen(Qt::black));

        double x1 = myLine.x1();

        double y1 = myLine.y1();

        double x2 = myLine.x2();

        double y2 = myLine.y2();

        QFont font = painter->font();

        font.setPixelSize(16);

        painter->setFont(font);

        QFontMetrics fm(painter->font());

        int textWidthInPixels = fm.width(mark_);

        int textHeightInPixels = fm.height();

        QTransform trans = painter->worldTransform();

        qDebug()<<trans;

        double scale = trans.m11();

        painter->scale(1/scale, 1/scale);

        double x_t = textWidthInPixels- 10;

        double y_t = y2 + textHeightInPixels/2;

        painter->drawText(QPoint(x_t*scale,y_t*scale),mark_);

    }

}