Drag and Drop

[cwnelatury]

Hey everyone

I want a picture label that is on top of another bigger picture label to be dragged and dropped.

so in essence...I want to move a label from one location to another.

There were some tutorials online but they were too advanced for me.

Could someone please show/simplify to me how to do this.

Thanks

[wysota]

What did you already try?

[cwnelatury]

I got the following drag and drop code from another program.
I think I have to mold this code with my program so it can drag picture labels.

I created my program using Qt designer...so i am a little lost how to change my ui_mainwindow.h so labels can be dragged.

Please help..
thanks




void DragWidget::dragEnterEvent(QDragEnterEvent *event)
{
if (event->mimeData()->hasFormat("application/x-dnditemdata")) {
if (event->source() == this) {
event->setDropAction(Qt::MoveAction);
event->accept();
} else {
event->acceptProposedAction();
}
} else {
event->ignore();
}
}

void DragWidget::dragMoveEvent(QDragMoveEvent *event)
{
if (event->mimeData()->hasFormat("application/x-dnditemdata")) {
if (event->source() == this) {
event->setDropAction(Qt::MoveAction);
event->accept();
} else {
event->acceptProposedAction();
}
} else {
event->ignore();
}
}

void DragWidget::dropEvent(QDropEvent *event)
{
if (event->mimeData()->hasFormat("application/x-dnditemdata")) {
QByteArray itemData = event->mimeData()->data("application/x-dnditemdata");
QDataStream dataStream(&itemData, QIODevice::ReadOnly);

QPixmap pixmap;
QPoint offset;
dataStream >> pixmap >> offset;

QLabel *newIcon = new QLabel(this);
newIcon->setPixmap(pixmap);
newIcon->move(event->pos() - offset);
newIcon->show();
newIcon->setAttribute(Qt::WA_DeleteOnClose);

if (event->source() == this) {
event->setDropAction(Qt::MoveAction);
event->accept();
} else {
event->acceptProposedAction();
}
} else {
event->ignore();
}
}

void DragWidget::mousePressEvent(QMouseEvent *event)
{
QLabel *child = static_cast<QLabel*>(childAt(event->pos()));
if (!child)
return;

QPixmap pixmap = *child->pixmap();

QByteArray itemData;
QDataStream dataStream(&itemData, QIODevice::WriteOnly);
dataStream << pixmap << QPoint(event->pos() - child->pos());

QMimeData *mimeData = new QMimeData;
mimeData->setData("application/x-dnditemdata", itemData);

QDrag *drag = new QDrag(this);
drag->setMimeData(mimeData);
drag->setPixmap(pixmap);
drag->setHotSpot(event->pos() - child->pos());

QPixmap tempPixmap = pixmap;
QPainter painter;
painter.begin(&tempPixmap);
painter.fillRect(pixmap.rect(), QColor(127, 127, 127, 127));
painter.end();

child->setPixmap(tempPixmap);

if (drag->exec(Qt::CopyAction | Qt::MoveAction, Qt::CopyAction) == Qt::MoveAction)
child->close();
else {
child->show();
child->setPixmap(pixmap);
}
}

[wysota]

I got the following drag and drop code from another program.
I think I have to mold this code with my program so it can drag picture labels.
And what doesn't work?


so i am a little lost how to change my ui_mainwindow.h so labels can be dragged.

We don't change ui_*.h files. We provide host classes for them.