How do I "move" an item from one QListWidget to another?

goetz

takeWidgetItem only removes the widget of the item which was set with setWidgetItem before. It does not remove the QListWidgetItem itself from the view; this is achieved with takeItem.

You can safely transfer a QListWidgetItem from on list widget to another:

@
void ListManager::on_addButton_clicked()
{
if( ui->leftList->count() == 0 )
// nothing to transfer...
return;

QListWidgetItem *widget = ui->leftList->takeItem( ui->leftList->currentRow() );
ui->rightList->addItem(widget);
}
@

This obviously works only with single selection mode of the list widget. For a multi-item selection mode you will have to do some more work.

Jonathan

Thanks Volker. This works and is reasonably "clean" code.

I still feel the more obvious "remove from left/add to right" approach should work.

Researching the model-view alternative is on my to-do list ;o)

goetz

Oh, you still do remove from the left and add to the right. The only difference is that you save yourself from creating a new item with new for the right view and delete item left over from the left view. Instead you just recycle the old one.

giesbert

That sounds like a better alternative than recreate it, gives less memory fragmentation... :-)

dangelog

[quote author="Gerolf" date="1292773031"]That sounds like a better alternative than recreate it, gives less memory fragmentation... :-)[/quote]

If you do care about memory framgentation Qt is the wrong toolkit for you :)

giesbert

Not always. If you need a UI toolkit that is perhaps cross platform, what else to use? wxWidgets? it's different, but better? I think no. And you can reduce the fragemntation but just don't use some things. The software we are creating is running 24/7 normally. So you should look at such things a bit, and where you can prevent, you should...

Jonathan

I successfully used the same "takeItem()" idea to remove an item from the right list and reinsert it at an index one above or one below its old location (ie to reprioritise the item in the list).

Jonathan

Perhaps the biggest hole in the Qt environment is the lack of integrated analysis tools, eg for memory leaks, performance analysis. The only option AFAIK is Valgrind.

giesbert

For linux, you use valgrin, for windows, I know no free solution, only commercial ones.
But for those tools, ther are already threads "here":http://developer.qt.nokia.com/forums/viewthread/2248 and "here":https://developer.qt.nokia.com/forums/viewthread/1924

vcsala

We had a thread "here":http://developer.qt.nokia.com/forums/viewthread/1924 which had discussed the such tools.

(Sorry for spaming, I was to slow and meantime Gerolf answered the question)

goetz

[quote author="Jonathan" date="1292788447"]Perhaps the biggest hole in the Qt environment is the lack of integrated analysis tools, eg for memory leaks, performance analysis. The only option AFAIK is Valgrind.[/quote]

Analysis tools are highly platform dependent, so it would be hard to provide this in a platform independent manner and quality like the Qt libs. I personally am convinced, that it is also out of scope for a toolkit.