Question

我有一个Qgraphicsscene作为一个类实现，然后我用QGraphicsScene :: mousePressEvent添加一个QGraphicsRectItem，这个项目也有一个QGraphicsRectItem :: mousePressEvent的实现，问题是rect项目中的事件传播到了场景，当我点击它添加一个新的矩形项目，但我想要的是，这个项目内的事件不会传播到场景，我尝试event-＆gt;接受，但事件传播，我怎么能这样做？谢谢你的帮助。

这是我的qgraphicsscene代码：

#include "imageview.h"

ImageView::ImageView(QWidget *parent){
    scene = new ImageScene(this);
    setScene(scene);
    //this->setMouseTracking(true);
    this->setInteractive(true);
}


ImageScene::ImageScene(QWidget *parent){
    current = NULL;
    selection = new QRubberBand(QRubberBand::Rectangle,parent);
    selection->setGeometry(QRect(10,10,20,20));
    setSceneRect(0,0,500,500);
}

void ImageScene::mousePressEvent(QGraphicsSceneMouseEvent *event){
    QGraphicsScene::mousePressEvent(event);
    /*IGNORING THIS EVENT FROM QGRAPHICSRECTITEM*/
    cout<<"image view"<<endl;
    if(this->selectedItems().length() == 0){ /*WORKS BUT IN SOME IMPLEMENTATION IS A PROBLEM (WHEN I DELETE THE ITEM WITH A DELETE BUTTON THE EVENT IS FIRED AND ADD A NEW ITEM .)*/
        origin = event->scenePos();
        selection->show();
    }
}
void ImageScene::mouseReleaseEvent(QGraphicsSceneMouseEvent *event){
    if(selection->isVisible() && selection->rect().width() >= 20 && selection->rect().height() >= 20){
        QGraphicsScene::mouseReleaseEvent(event);

        ResizableRect * rselection = new ResizableRect();
            //selection->origin = event->scenePos();
            //selection->grabMouse();
        cout<<"add"<<endl;
        this->addItem(rselection);
        rselection->setPos(selection->pos());
        rselection->setRect(0,0,selection->rect().width(),selection->rect().height());
    }
    selection->hide();

}
void ImageScene::mouseMoveEvent(QGraphicsSceneMouseEvent *event){
    QGraphicsScene::mouseMoveEvent(event);
    if(selection->isVisible()){
        QPoint rorigin(origin.x(),origin.y());
        int xdes = event->scenePos().x();
        int ydes = event->scenePos().y();
        xdes = xdes > 0? xdes:0;
        ydes = ydes > 0? ydes:0;
        xdes = xdes < this->width()?xdes:this->width();
        ydes = ydes < this->height()?ydes:this->height();

        QPoint rdest(xdes,ydes);
        selection->setGeometry(QRect(rorigin,rdest).normalized());
    }

}

Answer 1

与QWidgets相反，QGraphicsScene在子项目之前捕获事件。它在Qt文档中有描述。

为了正确使用它，请使用QGraphicsView而不是QGraphcisScene的重新实现。在那里重新实现mousePressEvent。

此时您可以在鼠标指针下确定项目。它就在那里 - 你可以调用QGraphicsView :: mousePressEvent（）; 它不是 - 使用您的实现添加新项目。

它还允许您分离不同视图的行为。

停止从QGraphicsItem到QGraphicsScene QT的事件传播

1 个答案: