Drag & Drop using QTableWidget

[jpn]

For drag and drop, take a look at Using Drag and Drop with Item Views - Using Convenience Views.

For context menu, you might want to reimplement contextMenuEvent() instead. More or less something like this:

void table_widget::contextMenuEvent(QContextMenuEvent *event) {
    QMenu popupMenu(this);
    popupMenu.addAction(...);
    popupMenu.exec(event->globalPos());
}

void table_widget::contextMenuEvent(QContextMenuEvent *event) {
    QMenu popupMenu(this);
    popupMenu.addAction(...);
    popupMenu.exec(event->globalPos());
}

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[Israa]

I fixed that problem, I just had to create a new QTableWidgetItem for each cell in the table.
I did have another question though, for dropEvent, it doesnt seem like the function is being called. I have it set up so that it prints a message when it enters that function but the message is never displayed. What could be wrong?
Here's the code for that function:

void table_widget::dropEvent(QDropEvent *event)
{
   printf("dropEvent\n");
   event->acceptProposedAction();
}

void table_widget::dropEvent(QDropEvent *event)
{
   printf("dropEvent\n");
   event->acceptProposedAction();
}

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I even tried inserting if (event->mimeData()->hasText()) before the printf() statement but that doesnt really do anything.

[guilugi]

Hello,

You have to do those two steps :

1 - call setAcceptDrops(true) on your tablewidget
2 - reimplement dragEnterEvent method, and accept it !

I'm not sure if the second step is absolutely necessary for a tablewidget, but the first is, for sure

Guilugi

[Israa]

I just had to reimplement dragMoveEvent() and it worked fine, thanks.

Now I'm having another 'problem'. In my project I'm trying to drag and drop from one QTableWidget to another but I can't quite get it right. The dragEnterEvent acknowledges when I've entered another QTableWidget but thats about it. Here's what I'm working with:

void table_widget::dragEnterEvent(QDragEnterEvent *event) 
{
	QTableWidgetItem* test = itemAt(event->pos());
    if  (test != 0)
    {
        if ( event->source() == this ) // same table, move entry
		{
			event->setDropAction( Qt::MoveAction );
			event->accept();
		}
		else // different table, add entry
		{
			printf("Different table\n");
			event->acceptProposedAction();
		}
 
	        source = itemAt(event->pos());
	        source->setText(itemAt(event->pos())->text());
    }
}
 
void table_widget::dropEvent(QDropEvent *event) 
{
		printf("I'm in dropEvent\n");
		itemAt(event->pos())->setText(source->text());
		if(source != itemAt(event->pos())) 
             source->setText("");
        event->acceptProposedAction();
}
 
void table_widget::dragMoveEvent(QDragMoveEvent *event)
{
         event->setDropAction(Qt::MoveAction);
         event->accept();
}

void table_widget::dragEnterEvent(QDragEnterEvent *event) 
{
	QTableWidgetItem* test = itemAt(event->pos());
    if  (test != 0)
    {
        if ( event->source() == this ) // same table, move entry
		{
			event->setDropAction( Qt::MoveAction );
			event->accept();
		}
		else // different table, add entry
		{
			printf("Different table\n");
			event->acceptProposedAction();
		}
	
	        source = itemAt(event->pos());
	        source->setText(itemAt(event->pos())->text());
    }
}

void table_widget::dropEvent(QDropEvent *event) 
{
		printf("I'm in dropEvent\n");
		itemAt(event->pos())->setText(source->text());
		if(source != itemAt(event->pos())) 
             source->setText("");
        event->acceptProposedAction();
}

void table_widget::dragMoveEvent(QDragMoveEvent *event)
{
         event->setDropAction(Qt::MoveAction);
         event->accept();
}

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Any suggestions?

[ghorwin]

I have exactly the same problem. I called set setAcceptDrops(true) and reimplemented dragEnterEvent(QDragEnterEvent *event), which gets called and I accept the proposed copy-action.

However, my reimplemented dropEvent function is never called. The documentation and examples say it will be called, but I couldn't get this to work :-(

Btw, this is Qt Open Source 4.2.2.

Any suggestions?

[ghorwin]

Correction to my last post: It is Qt Open Source 4.2.1

I believe I have found the problem. In qtablewidget.h, in the class declaration for QTableWidget the function dropEvent() is not declared as virtual, thus our reimplemented dropEvent() function will never be called.

I guess I have to check with 4.2.2 and see if this was fixed...

Andreas

[jpn]

I believe I have found the problem. In qtablewidget.h, in the class declaration for QTableWidget the function dropEvent() is not declared as virtual, thus our reimplemented dropEvent() function will never be called.

It's declared virtual in QWidget.
http://www.qtcentre.org/forum/p-reim...ostcount5.html

[ghorwin]

Yes, that's why it works when you inherit from QTableView... however, QTableWidget provides its own implementation of dropEvent() without declaring it virtual. Therefore classes deriving from QTableWidget will not be able to reimplement that function, or if they do the function will never get called.

Andreas

[jpn]

Actually, it doesn't matter if QTableWidget marks it virtual or not. It has already been declared as virtual in the base class, in QWidget that is.

Once a method was declared as virtual, it will be virtual in all subclasses, regardless if one uses the "virtual" keyword or not.