QListView & item movement

shahriar25

Hi,
I have a QListView and it's a listview for showing the queue in my music player project. I have two problems:

first: i want the user to be able to move the items up and down by draging and droping them. I set the dragDropMode to internalMove and the dafaultDropAction to targetMoveAcion but when I run the app and move the items they go into each other.
what can I do about that? (QListWidget doesn't have this problem)

second: I need to know which Item is moved and where is it moved to so I can be able to update the QMediaPlayer->playList(). how can I do that?

SGaist

Hi,

What do you mean by "they go into each other" ?

You can use the indexesMoved method to get the information and rebuild the playlist from there.

shahriar25

@SGaist I mean when you move the Item in QListView you can drop the item between two items or on another item. when you drop it on another item the other item disappears and the moved item takes its place. I think it replaces the item's data

and also I need to know where the index is moved to. is that possible?

SGaist

Are you using the QListView in Icon mode or List mode ?

shahriar25

@SGaist I'm using it in list mode

SGaist

Can you share how you setup your QListView ?

shahriar25

@SGaist
I create a queueModel and set the listView's model to queue model. the Items in queueModel have a few userRole data. this is the slot that connets to doubleClicked signal on a track that I have in my trackModel:

for (int i=0; i<trackModel->rowCount(); ++i)
{
queueModel->setItem(i, trackModel->item(i)->clone());

    const QPixmap *artWork = new QPixmap;
    artWork = ui->trackArtLabel->pixmap();
    queueModel->item(i)->setIcon(QIcon(*artWork));

    QString itemTitle=QString("%1\n%2\n%3")
            .arg(queueModel->item(i)->data(Qt::UserRole+3).toString())
            .arg(queueModel->item(i)->data(Qt::UserRole+4).toString())
            .arg(queueModel->item(i)->data(Qt::UserRole+6).toString());

    queueModel->item(i)->setText(itemTitle);
}

for (int i=0; i<queueModel->rowCount(); ++i)
{
    mediaPlayer.playlist()->addMedia(QMediaContent(QUrl::fromLocalFile(queueModel->item(i)->data(Qt::UserRole+1).toString())));
}

playQueue(item.data(Qt::UserRole+7).toInt());

SGaist

You have a memory leak here. You allocate artWork on the heap and then directly replace its value by the one from trackArtLabel's pixmap. There's no need for that allocation.

Is your queueModel a custom model ?

shahriar25

@SGaist
yes you are right. I'm using QStandardItemModel

shahriar25

Any help would be appreciated.

SGaist

Again, can you show how you initialize your QListView and your model ?

shahriar25

Hi, @SGaist I'm sorry I didn't get the question in the first place
the QListview is initialized from the ui with these

queueView->setObjectName(QStringLiteral("queueView"));
queueView->setEnabled(true);
queueView->setFrameShape(QFrame::NoFrame);
queueView->setFrameShadow(QFrame::Plain);
queueView->setSizeAdjustPolicy(QAbstractScrollArea::AdjustIgnored);
queueView->setEditTriggers(QAbstractItemView::NoEditTriggers);
queueView->setDragEnabled(false);
queueView->setDragDropMode(QAbstractItemView::InternalMove);
queueView->setDefaultDropAction(Qt::TargetMoveAction);
queueView->setAlternatingRowColors(false);
queueView->setSelectionBehavior(QAbstractItemView::SelectItems);
queueView->setIconSize(QSize(150, 150));
queueView->setMovement(QListView::Snap);
queueView->setResizeMode(QListView::Adjust);
queueView->setSpacing(0);
queueView->setViewMode(QListView::ListMode);
queueView->setModelColumn(0);

and the model:

QStandardItemModel *queueModel;

queueModel = new QStandardItemModel(this);

ui->queueView->setModel(queueModel);

asanka424

Ideally you want the dragged item to be placed between existing items, right? You can change standard item flags to disable drops. (ItemIsDropEnabled).

And for getting new index perhaps you can use itemChanged signal?

shahriar25

Hi @asanka424
I tried the Qt::itemIsDropEnabled but the Items in the model get disabled. what should I do?

asanka424

@shahriar25
Hi,
Did you disable drops in QStandardItem or ListView? You have to disable drops in QStandardItem not in the view
setDropEnabled(false)

BTW if you want to implement more custom behaviours I encourage to use QAbstractItemModel where you have more control over these operations.

Thanks

shahriar25

@asanka424
Hi,
I did this in a "for" for every Item:

queueModel->item(i)->setFlags(Qt::ItemIsDropEnabled);

And also I used QStandardModel in my app a lot but if this thing that I want can't be done in QStandardModel I will have to change the model. And also note that QListWidget doesn't have this problem

asanka424

this will enable drops in each item in your model. what you should do is disabling it like this

item->setFlags(item->flags() ^ Qt::ItemIsDropEnabled)

shahriar25

Hi @asanka424 @SGaist
I was able to set the item flags correctly but now I'm having problem with item changed signal.
How do I know where was the Item (it's row) before it was moved? (I can set the item's data to hold the current row but isn't there a better way?)

And also I was searching the QStandardItemModel's signals to find something useful and I found QStandardItemModel::rowsMoved(...) and QStandardItemModel::rowsAboutToBeMoved(...) and I tried them but they don't ge triggred when an item is moved. why is that?

asanka424

You can try dataChanged signal but it won't identify moves explicitly.

BTW does drag and drop work as you expected now?

shahriar25

Hi @asanka424
Yes it does. if it won't work then I will have to set the user data every time an item moves. but I think there has to be another way.