QPainter:begin: A paint device can only be painted by one painter at a time解决思路

QPainter::begin: A paint device can only be painted by one painter at a time
程序：
paintEvent()
{

          tank-> paint();
          if(istrue==1)
                      zidan-> paint();
}

当isture==1的时候会出现错误
QPainter::begin:   A   paint   device   can   only   be   painted   by   one   painter   at   a   time

到底怎么了
这是个qt程序

------解决方案--------------------
。。请把问题说得清楚些，不然谁都不知道你出问题在哪里。。