Grid layout reordering after modifications

[mrjj]

Hi
I was wondering.
If I make a layout in designer, say a grid layout and put buttons 1,2,3,4,5 in it,
then I delete 3. the others are rearranged so no holes.

So I wonder what will happen if you call activate() on layout after u removed the
button(s).

[kshegunov]

@mrjj
Hm, indeed, no need to call activate even. If I comment out the taking-out-and-reinserting code the layout is rearranged automatically after the delete button. This is however a bit strange for me, because how is the layout supposed to know the number of columns/rows I'm expecting?

Nope, this seems to "work" only if I have a single row in the layout, otherwise I get a hole at the place the button was supposed to be.

[mrjj]

Im not sure its expecting anything. just seems to start with
first Layoutitem and then then just position one by one.

The number of rows seems to the height / items.
if I set minimum height to such degree they can not longer fit with
in layout_height, they start to overlap.

Ahh. the hole is a "column"

[kshegunov]

@mrjj
Well not a whole column, but a single item in the grid. I could add more buttons to the layout for testing purposes, but since a picture is worth a thousand words, I think the link explains what's my issue quite well.

[mrjj]

@kshegunov
Yes pictures made it very clear.
Try to reproduce it in Creator. Its seems to
rearrange.

[kshegunov]

@mrjj
Do you mean to make the form in the designer? Unfortunately, in this case this is not an option, see the linked thread for details as to why.

[mrjj]

@kshegunov
I know u cant use UI file.
Im just wondering why in creator,
if I create a grid 3x2 with buttons.
Then from code, i take() and delete say button 3, i
get no holes. But in AgDial there is.
I should get the same, shouldn't I?

[kshegunov]

@mrjj
I suppose so. But I'm not takeing the item itself, maybe this is why the behavior differs. I'll try it out.
Nope, substituting the relevant reinsertion code with:

	delete layout->takeAt(index);
	delete button;
	buttons.erase(i);

Produces the same hole. I have no idea why this works in your case ...

[mrjj]

Just to be sure, we are talking
about a normal gridlayout in a widget?
At runtime, there should be no difference between one from
UI files and one from code.
So your case must be different or mine too simple.

[kshegunov]

@mrjj

Just to be sure, we are talking
about a normal gridlayout in a widget?

Absolutely! Here's how a create a page:

bool AgDialPrivate::createPage(QAction * action)
{
	Q_ASSERT(action);
	QList<QAction *> children = action->findChildren<QAction *>(QString(), Qt::FindDirectChildrenOnly);
	if (children.count() <= 0 || pages.value(action, NULL))
		return false;

	// Create a page for this action
	AGUI_Q(AgDial);

	QWidget * page = new QWidget(q);
	new QGridLayout(page);

	pages.insert(action, page);
	q->addWidget(page);

	// Create a return button
	QAction * parent = qobject_cast<QAction *>(action->parent());
	createReturnButton(page, parent);

	// If the action has any children, create their buttons and/or pages
	foreach (QAction * child, children)  {
		createButton(child);
		if (child->children().count() > 0)
			createPage(child);
	}

	// Map the triggered signal of the child action
	QSignalMapper * mapper = new QSignalMapper(page);
	mapper->setMapping(action, page);
	QObject::connect(action, SIGNAL(triggered()), mapper, SLOT(map()));
	QObject::connect(mapper, SIGNAL(mapped(QWidget *)), q, SLOT(setCurrentWidget(QWidget *)));

	return true;
}

[mrjj]

Ok, i delete sample and tried again.
Now I get hole too! ?
only difference is that I had min/max heights in other test.

[mrjj]

Ok. now even in Creator it leaves holes.
my first sample must not been proper.

[kshegunov]

@mrjj said:

only difference is that I had min/max heights in other test.

Maybe the layout's redistribution of item space had hidden the effect in the previous test? I couldn't think of another reason.

[mrjj]

@kshegunov
I agree . must been something like that as now the effect
is 100% as your experience. Even in designer.
Sorry for the confusion.