signals: void SendforeColor(const QChar &);
void PaintArea::SendforeColor(QColor &color){ color=QColor(foreColor);}
void MainWindow::recieveforeColor(const QColor &color){ foreColor=QColor(color); QPixmap pix=QPixmap(80,80); pix.fill(foreColor); ui->toolButton_3->setIcon(QIcon(pix));} connect(area,SIGNAL(SendforeColor(QColor &)),this,SLOT(recieveforeColor(QColor &)));能这样写不