Draggable ItemWidget in treeWidget

[clementNg]

I have set itemWidget ( QPushButton ) to my treeWidget but I cannot drag and drop for the treeWidgetItem. As I want to swap the item between two treeWidgets with custom itemWidget ( QPushButton ) . Is there any ways and any things to set for me to make it become draggable? Or i need create a draggable button? Also, is there any examples for me? Thank you very much.

[Pl45m4]

@clementNg

You have to set flags for your treeWidgetItem.

yourTreeItem->setFlags(Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsDragEnabled);

You also have to set the "Drop"-flag for your root-item (where you want to drop your treeItems i.e. your buttons).

[clementNg]

@Pl45m4
Thank you. But my itemWidget still cannot drag and drop after I have tried your method. Is there any other suggestation? Thanks.

[Christian Ehrlicher]

Then please show us some your code, best would be a complete small example which shows your problem.

[clementNg]

@Christian-Ehrlicher

This is my custom TreeWidget and i would emit the signal if they trigger the corresponding event

DragDropTreeWidget::DragDropTreeWidget(QWidget *parent) : QTreeWidget(parent)
{
    setAcceptDrops(true);
    this->m_isDragRemoveItem = false;
}

void DragDropTreeWidget::mousePressEvent(QMouseEvent *event)
{
    qDebug() << "mousePressEvent";
    if (event->button() == Qt::LeftButton) {
        startPoint = event->pos();
    }
    QTreeWidget::mousePressEvent(event);
}

void DragDropTreeWidget::mouseMoveEvent(QMouseEvent *event)
{
    qDebug() << "mouseMoveEvent";
    QTreeWidget::mouseMoveEvent(event);
}

void DragDropTreeWidget::dragEnterEvent(QDragEnterEvent *event)
{
    qDebug() << "dragEnterEvent";
    DragDropTreeWidget *source =
            qobject_cast<DragDropTreeWidget *>(event->source());
    if (source && source != this) {
        event->setDropAction(Qt::MoveAction);
        event->accept();
    }
}

void DragDropTreeWidget::dragLeaveEvent(QDragLeaveEvent *event)
{
    qDebug() << "dragLeaveEvent";
    QTreeWidget::dragLeaveEvent(event);
    emit dragLeaveEventAction();
}

void DragDropTreeWidget::dragMoveEvent(QDragMoveEvent *event)
{
    qDebug() << "dragMoveEvent";
    DragDropTreeWidget *source =
            qobject_cast<DragDropTreeWidget *>(event->source());
    if (source && source != this) {
        emit dragMoveEventAction(event->pos());
    }
}

void DragDropTreeWidget::dropEvent(QDropEvent *event)
{
    qDebug() << "dropEvent";
    DragDropTreeWidget *source =
            qobject_cast<DragDropTreeWidget *>(event->source());
    if (source && source != this) {
        emit dropEventAction();
    }
}

Currently , I am trying to create a custom pushButton which is close to the above class to handle the pushbutton drag event. As I am still trying to implement it, it is not completed. However, using dragEnterEvent as an example, i cannot get event->source() after drag the button and it crashed. Also some of the action between the treeWidget and pushbutton would be duplicated and I dun know which one should be needed?

DragDropPushButton::DragDropPushButton(QWidget *parent)
    : QPushButton(parent)
{
    this->setAcceptDrops(true);
}

void DragDropPushButton::mousePressEvent(QMouseEvent *event)
{

    qDebug() << "button mousePressEvent";
    startPoint = event->pos();
    DragDropPushButton* source = this;
    qDebug() << "button name: " + source->text();
    quintptr address=(quintptr)source;
    QByteArray byteArray(QString::number(address).toLatin1());


//    QByteArray byteArray(reinterpret_cast<char*>(&source),sizeof(QWidget*));
    QDrag *drag = new QDrag(this);
    QMimeData * mimeData = new QMimeData;
    mimeData->setData("button",byteArray);
    drag->setMimeData(mimeData);

    QPoint globalPos = mapToGlobal(event->pos());
    QPoint p = source->mapFromGlobal(globalPos);
    drag->setHotSpot(p);
    drag->setPixmap(source->grab());
    drag->exec(Qt::CopyAction | Qt::MoveAction);

    QPushButton::mousePressEvent(event);
}

void DragDropPushButton::mouseMoveEvent(QMouseEvent *event)
{
    qDebug() << "button mouseMoveEvent";
    QPushButton::mouseMoveEvent(event);
}

void DragDropPushButton::dragEnterEvent(QDragEnterEvent *event)
{
    DragDropPushButton *source;
    if(event->source() != nullptr) {
        source = qobject_cast<DragDropPushButton *>(event->source());
    } else {
        source = qobject_cast<DragDropPushButton *>(this);
    }
    if (source && source != this) {
        event->setDropAction(Qt::MoveAction);
        event->accept();
    }
}

voidDragDropPushButton::dragLeaveEvent(QDragLeaveEvent *event)
{
    qDebug() << "dragLeaveEvent";
    QPushButton::dragLeaveEvent(event);
//    emit dragLeaveEventAction();
}

void DragDropPushButton::dragMoveEvent(QDragMoveEvent *event)
{
    DragDropPushButton *source;
    if(event->source() != nullptr) {
        source = qobject_cast<DragDropPushButton *>(event->source());
    } else {
        source = qobject_cast<DragDropPushButton *>(this);
    }
}

void DragDropPushButton::dropEvent(QDropEvent *event)
{
    qDebug() << "button dropEvent";
    if (event->mimeData()->hasFormat("button")) {

        QByteArray pieceData = event->mimeData()->data("button");
        DragDropPushButton * button = reinterpret_cast<DragDropPushButton*>((ChartsChartsDesignFormDragDropPushButton*)pieceData.toULongLong());
        qDebug() << "button Name : " + button->text();

        event->setDropAction(Qt::MoveAction);
        event->accept();

    }
}

[Pl45m4]

@clementNg said in Draggable ItemWidget in treeWidget:

ChartsChartsDesignFormDragDropPushButton

Why you are using a class name this long? :o
It doesnt increase the readability of your code :)

[clementNg]

@Pl45m4
oh sorry. Changed to be a shorter name