接受 QGraphicsScene 上的放置
我正在尝试为 QGraphicsScene 实现拖放。以下是我已超载的事件：
void TargetScene::dragEnterEvent(QGraphicsSceneDragDropEvent *event) {
bool acceptDrag = false;
const QMimeData* mime = event->mimeData();
// Is an image present?
if (mime->hasImage()) {
QImage img = qvariant_cast<QImage>(mime->imageData());
dragPix = QPixmap::fromImage(img);
acceptDrag = !dragPix.isNull();
}
event->setAccepted(acceptDrag);
}
void TargetScene::dropEvent(QGraphicsSceneDragDropEvent *event) {
// Add dragged pixmap to scene
QGraphicsPixmapItem* newPix = this->addPixmap(dragPix);
newPix->setPos(event->pos().x(), event->pos().y());
}
场景仍然不会接受掉落。我猜这是因为我无法在我的 QGraphicsScene 上执行 setAcceptDrops(true) 。
如何接受图形场景中的掉落？
I'm trying to implement drag'n'drop for a QGraphicsScene. Here are the events I've overloaded:
void TargetScene::dragEnterEvent(QGraphicsSceneDragDropEvent *event) {
bool acceptDrag = false;
const QMimeData* mime = event->mimeData();
// Is an image present?
if (mime->hasImage()) {
QImage img = qvariant_cast<QImage>(mime->imageData());
dragPix = QPixmap::fromImage(img);
acceptDrag = !dragPix.isNull();
}
event->setAccepted(acceptDrag);
}
void TargetScene::dropEvent(QGraphicsSceneDragDropEvent *event) {
// Add dragged pixmap to scene
QGraphicsPixmapItem* newPix = this->addPixmap(dragPix);
newPix->setPos(event->pos().x(), event->pos().y());
}
The scene still won't accept drops. I'm guessing that's because I can't do setAcceptDrops(true) on my QGraphicsScene.
How do I accept drops on a graphics scene?
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评论（1）
这里的技巧是还要接受 QGraphicsScene::dragMoveEvent() 中的事件！
原因是如果鼠标下没有项目，默认实现会忽略拖放事件！
另请参阅：http://www.qtcentre.org/threads /8022-QGraphicsScene-doesn-t-accept-Drops
干杯
The trick here is to ALSO accept the event in the QGraphicsScene::dragMoveEvent()!
The reason is the DEFAULT implementation which ignores drag and drop events if there is no item under the mouse!
Also refer to: http://www.qtcentre.org/threads/8022-QGraphicsScene-doesn-t-accept-Drops
Cheers