mouseEvent in QScrollArea giving wrong position ?

[barnabyr]

Hi !

I Have a subclassed QScrollArea with a grid layout and it is dynamically filled with lots of thumbnails.
Each thumbnail image is placed into a QFrame which is then added into the grid layout
.. When they are all added I call adjustSize() and show the scrollarea.

I have reimplemented the scroll area's mousePressEvent(QMouseEvent *e) and to query
whether a thumbnail is being clicked my code is like this:

for (int i = 0; i < m_grdLayout->count(); i++)
{
   QLayoutItem *layoutItem = m_grdLayout->itemAt(i);
   if (layoutItem->geometry().contains(e->pos()))
   {
      return layoutItem->widget();
   }
}

for (int i = 0; i < m_grdLayout->count(); i++)
{
   QLayoutItem *layoutItem = m_grdLayout->itemAt(i);
   if (layoutItem->geometry().contains(e->pos()))
   {
      return layoutItem->widget();
   }
}

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It didn't work and I investigated it ... it seemed that the y coordinate e->pos() was
returning were always the same .. regardless of the size of the scroll area or where I
clicked within it. (up the top or down the bottom)

It was like the postion was relative to the boundary of the containing widget .. not the
scroll area.

I tried using every mapTo and mapFrom I could think of to transform pos of but I could
never get the position in the mouse event to be relative to the place in the scroll area it
was supposed to be.

so I changed my code to :

for (int i = 0; i < m_grdLayout->count(); i++)
{
	QLayoutItem *layoutItem = m_grdLayout->itemAt(i);
	QWidget * w = layoutItem->widget();
	if (w->underMouse())
		return w;
}

for (int i = 0; i < m_grdLayout->count(); i++)
{
	QLayoutItem *layoutItem = m_grdLayout->itemAt(i);
	QWidget * w = layoutItem->widget();
	if (w->underMouse())
		return w;
}

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which works properly.

But why didn't my first try work ? What was I doing wrong ?

thanks for any pointers

barnaby.