我想在将QGraphicsRectItem添加到场景后移动它。它可以移动,但是离鼠标指针有一定的偏移量。我认为这只是将鼠标指针位置加到其原始位置上。我不知道如何解决这个问题。
以下是我的代码:
class ucFilter : public QGraphicsItem {
std::shared_ptr<QGraphicsRectItem> m_rect;
std::shared_ptr<QGraphicsTextItem> m_text;
std::shared_ptr<QString> m_name;
std::shared_ptr<QPointF> m_pos;
QGraphicsItem* selectedItem;
bool m_mouseGrabbed;
public:
static const int default_x = 80, default_y=40;
ucFilter::ucFilter(QString &name, QPointF &pos){
m_name = shared_ptr<QString>(new QString(name));
m_pos = shared_ptr<QPointF>(new QPointF(pos));
m_rect = shared_ptr<QGraphicsRectItem>( new QGraphicsRectItem(pos.x()-default_x, pos.y()-default_y, 2*default_x, 2*default_y ));
m_text = shared_ptr<QGraphicsTextItem>( new QGraphicsTextItem(name));
m_text->setPos(pos.x() - m_text->boundingRect().width()/2, pos.y()- 30);
selectedItem = NULL;
m_mouseGrabbed = false;
}
QGraphicsRectItem* getRect() { return m_rect.get(); }
QGraphicsTextItem* getText() { return m_text.get(); }
QString* getName() { return m_name.get(); }
QPointF* getPos() { return m_pos.get(); }
void setPos(QPointF newPos) { m_pos->setX(newPos.x()); m_pos->setY(newPos.y()); }
QRectF ucFilter::boundingRect() const
{
return m_rect->boundingRect();
}
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
Q_UNUSED(widget);
//QBrush brush(
if (!m_mouseGrabbed){ grabMouse(); m_mouseGrabbed = true; }
}
void mousePressEvent(QGraphicsSceneMouseEvent *event){
selectedItem = this;
QGraphicsItem::mousePressEvent(event);
}
void mouseReleaseEvent(QGraphicsSceneMouseEvent *event){
selectedItem = NULL;
QGraphicsItem::mouseReleaseEvent(event);
}
void mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
if(NULL != selectedItem){
m_text->setPos(event->pos());
m_rect->setPos(event->pos());
}
QGraphicsItem::mouseMoveEvent(event);
}
};
ucFilter对象在场景dropEvent中创建:
void cGraphicsScene::dropEvent(QGraphicsSceneDragDropEvent * event){
QTreeView* source = static_cast<QTreeView*>(event->source());
string name = event->mimeData()->text().toUtf8().constData();
if(0 == name.length()){
event->acceptProposedAction();
return ; // nothing to do anymore
}
QPointF pos = event->scenePos ();
shared_ptr<ucFilter> newFilter = shared_ptr<ucFilter>(new ucFilter(event->mimeData()->text(),event->scenePos ()));
m_filters.push_back(newFilter);
this->addItem(newFilter->getRect());
this->addItem(newFilter->getText());
this->addItem(newFilter.get()); // also add the item to grab mouse events
event->acceptProposedAction();
}
我希望矩形能够在鼠标所在位置绘制。
std::shared_ptr
疯狂了。您不需要将任何成员存储为指针。您的项目拥有其子项和其他任何参数。按值存储它们。你所做的是我见过的最令人发指的模仿编程行为。有人让你相信共享指针是正确的选择,但你不明白为什么以及何时使用它们,却滥用它们。这真的非常糟糕。您的初始化列表在哪里?通过const引用传递?呃。。。 - Kuba hasn't forgotten Monica