QFont font;
font.setPointSize(18);
painter.setFont(font);
QFontMetrics fm = painter.fontMetrics();
QString list[] = {"A","B","C","D","E"};
for(int i=0;i<5;i++)
{
int width = fm.width(list[i]);
int height = fm.ascent()+fm.descent();
QPair<int,int> pos(mDatas[i]);
QRectF rect(pos.first-width/2,pos.second-height/2,width,height);
painter.drawText(rect,list[i]);
}