moving labels to exact location with mouse move event resulted in jumpy locations

[faizol]

Hi all,

I've searched and read several documents and threads regarding exact positioning of a child widget. I tried to code it but still having a problem.

Here's my code;

void BoxExample::mouseMoveEvent(QMouseEvent *event)
{
    if(_mouseLeftPressed && this->objectName()=="Box_A"){ // Box_A type QLabel
 
        this->move(mapToParent(event->pos()-_offset)); // Box_A moves as expected
 
        _tmp=this->parentWidget()->findChild<QWidget *>("Box_B"); // Box_B type QLabel
        if(_tmp){
              _tmp->move(mapToParent( QPoint(0, event->pos().y()-_offset.y()) ) );// Box_B jumps around
              _tmp=NULL;
        }
 
    }
}

void BoxExample::mouseMoveEvent(QMouseEvent *event)
{
    if(_mouseLeftPressed && this->objectName()=="Box_A"){ // Box_A type QLabel

        this->move(mapToParent(event->pos()-_offset)); // Box_A moves as expected

        _tmp=this->parentWidget()->findChild<QWidget *>("Box_B"); // Box_B type QLabel
        if(_tmp){
              _tmp->move(mapToParent( QPoint(0, event->pos().y()-_offset.y()) ) );// Box_B jumps around
              _tmp=NULL;
        }

    }
}

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I can get Box_A to move exactly where I wanted it to be, but Box_B which is supposed to be sliding up and down the Y axis is jumping around in the parent widget. What's the right method for the child coordinate transformation?


------------------------------------------------------------------------

I solved it by passing this->pos().y() position directly to Box_B.

void BoxExample::mouseMoveEvent(QMouseEvent *event)
{
    if(_mouseLeftPressed && this->objectName()=="Box_A"){ // Box_A type QLabel
 
        this->move(mapToParent(event->pos()-_offset)); // Box_A moves as expected
 
        _tmp=this->parentWidget()->findChild<QWidget *>("Box_B"); // Box_B type QLabel
        if(_tmp){
              _tmp->move(QPoint(0, this->pos().y() ));// Box_B slides up and down Y axis
              _tmp=NULL;
        }
 
    }
}

void BoxExample::mouseMoveEvent(QMouseEvent *event)
{
    if(_mouseLeftPressed && this->objectName()=="Box_A"){ // Box_A type QLabel

        this->move(mapToParent(event->pos()-_offset)); // Box_A moves as expected

        _tmp=this->parentWidget()->findChild<QWidget *>("Box_B"); // Box_B type QLabel
        if(_tmp){
              _tmp->move(QPoint(0, this->pos().y() ));// Box_B slides up and down Y axis
              _tmp=NULL;
        }

    }
}

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Still do not understand the whole mechanism behind child parent transform properly. It seems that all transformations are done relatively, right?


Thanks.

Cheers,
Faizol