Question

我有一个来自QGraphicsItem的类RadBox。我希望项目具有不同的背景和前景颜色，具体取决于其场景是显示，打印还是复制到剪贴板。以下是项目paint()方法：

void RadBox::paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
           QWidget *widget)
{
    if(isSelected()) painter->setPen(grayPen);
    else painter->setPen(blackPen);
    if(standing!=0) painter->setBrush(redBrush);
    else painter->setBrush(grayBrush);
    painter->drawRoundedRect(-35, -30, 70, 60, 3, 3);
    painter->setFont(fnt);
    painter->drawText(QRectF(-35,-10,70,20),Qt::AlignCenter,QString::number(box_number));
    painter->setFont(fnt2);
    painter->drawText(QRectF(-35,5,70,20),Qt::AlignCenter,QString::number(power));
}

复制到剪贴板：

void Scheme::on_copyButton_clicked()
{
    QPixmap pm(scene.itemsBoundingRect().width()*3,scene.itemsBoundingRect().height()*3);
    QPainter pnt;
    pnt.begin(&pm);
    scene.render(&pnt);
    pnt.end();
    QApplication::clipboard()->setPixmap(pm,QClipboard::Clipboard);
}

印刷：

void Scheme::print_preview(QPrinter* printer)
{
    QPainter pnt;
    pnt.begin(printer);
    scene.render(&pnt);
    pnt.end();
}

如果场景被绘制，打印或复制，如何让项目知道？

Answer 1

回答自己：painter->device()有一名成员devType()。

switch(painter->device()->devType())
{
case QInternal::Widget:
    if(isSelected()) painter->setPen(grayPen);
    else painter->setPen(blackPen);
    if(standing!=0) painter->setBrush(redBrush);
    else painter->setBrush(grayBrush);
    break;
case QInternal::Pixmap:
case QInternal::Printer:
    painter->setPen(blackPen);
    painter->setBrush(QBrush(Qt::white));
    break;
default:
    break;
}

QGraphicsItem :: paint（）：如何检查是否打印了QGraphicsScene

1 个答案: