[提问]QGraphicsView拖拽图片时如何不露出白色的底 [复制链接]

QGraphicsView如何实现拖拽图像到达图像边缘的时候无法再拖拽，不会露出白边如下图：

图片:QQ截图20161228163859.jpg

而不是像下图这样：

图片:QQ截图20161228163909.jpg

不知道QGraphicsView有没有直接设置的方法

QVariant GraphicsItem::itemChange(QGraphicsItem::GraphicsItemChange change, const QVariant &value)
{
    if ( change == QGraphicsItem::ItemSelectedHasChanged ) {
        QGraphicsItemGroup *g = dynamic_cast<QGraphicsItemGroup*>(parentItem());
        if (!g)
            setState(value.toBool() ? SelectionHandleActive : SelectionHandleOff);
        else{
            setSelected(false);
            return QVariant::fromValue<bool>(false);
        }
    }

    else if (change == ItemPositionChange && scene()) {
        // value is the new position.
        QPointF newPos = value.toPointF();
        QRectF rect = scene()->sceneRect();
        if (!rect.contains(newPos)) {
            // Keep the item inside the scene rect.
            newPos.setX(qMin(rect.right()-boundingRect().width()/2, qMax(newPos.x(), rect.left()+boundingRect().width()/2)));
            newPos.setY(qMin(rect.bottom()-boundingRect().height()/2, qMax(newPos.y(), rect.top()+boundingRect().height()/2)));
            return newPos;
        }
    }

    return QGraphicsItem::itemChange(change, value);
}

超过范围后，改变鼠标状态变成释放，把图片移到边缘位置