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Drag & Drop in ListBox

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Manivannan_1984

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1

Tuesday, February 27th 2007, 10:58am

Drag & Drop in ListBox

Hi All,

Now i am trying to implement Drag & Drop in QListBox.

I am using Qt3.3.6... I went thru all the posts reg drag & drop..

I set the following..

Source code

 
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setAcceptDrops(true);
setDragSelect(true);
viewport ()->setAcceptDrops(true);


I didn't get clear idea.

Any body can help me out, if u can post a sample code that will be very useful..

Thanks,
mani
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sunil.thaha

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2

Tuesday, February 27th 2007, 11:31am

RE: Drag & Drop in ListBox

This should help
sunil.thaha has attached the following file:

Manivannan_1984

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3

Tuesday, February 27th 2007, 11:48am

RE: Drag & Drop in ListBox

hi Sunil,

Thanks for your sample code...

My problem is, I have designed aa Ui and using this in my class which has a list box and some other stuffs..

There, the below functions are not called when I do drag... I have overloaded the below functions...

Quoted

void contentsDragEnterEvent(QDragEnterEvent *event);
void contentsDropEvent(QDropEvent *event);


I didn't inherit QListbox directly to my class, if do I will get many errors..

How this can be solved..?
[PHP]

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This post has been edited 1 times, last edit by "Manivannan_1984" (Feb 27th 2007, 12:47pm)

sunil.thaha

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4

Tuesday, February 27th 2007, 2:28pm

RE: Drag & Drop in ListBox

Quoted


I didn't inherit QListbox directly to my class,


You should inherits from the QListBox since the void contentsDragEnterEvent(QDragEnterEvent *event), and the void contentsDropEvent(QDropEvent *event) are virtual functions of QScrollView and QListBox inherits it. you will receive these event in the QListBox subclass

Quoted


if do I will get many errors..
How this can be solved..?

Like what ... ?

Manivannan_1984

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5

Wednesday, February 28th 2007, 5:32am

RE: Drag & Drop in ListBox

Finally I planned to overwrite the my class files generated from UI..

ie; I am creating a new class which has QListBox as its base and using this class in my UI instead of QListBox..

To perform drag&drop whether Should I insert elements as ListBoxItems? If I do insert elemets as string will it work?

Regards,
mani
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sunil.thaha

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6

Wednesday, February 28th 2007, 5:37am

RE: Drag & Drop in ListBox

There isn't any need to subclass QListBoxItems for drag drop support. You can define a custom widget in the Designer and use it in place of the ListBox

Manivannan_1984

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7

Wednesday, February 28th 2007, 8:37am

RE: Drag & Drop in ListBox

Hi Sunil.. Pls find my below code what I used from ur sample...

But it doesn't works correctly for me..

Source code

 
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ProjectView::ProjectView(QWidget *parent, const char *name)
    : QListBox(parent, name)
{
	setAcceptDrops(true);	
}

void ProjectView::mousePressEvent(QMouseEvent *a_event)
{
	QListBox::mousePressEvent( a_event );
    dragging = TRUE;
}

void ProjectView::mouseMoveEvent(QMouseEvent *a_event)
{
	if ( dragging ) 
	{
		int distance = (a_event->pos() - dragPos).manhattanLength();
        if (distance > QApplication::startDragDistance())
		{
			QDragObject *d = new QTextDrag( currentText(), this );
			d->drag(); // do NOT delete d.
			dragging = FALSE;
		}
	}     
}

void ProjectView::dragEnterEvent(QDragEnterEvent *a_event)
{
	if ( QTextDrag::canDecode( a_event ) )
	{
		 a_event->accept();
	}
}

void ProjectView::dropEvent(QDropEvent *a_event)
{
    QString text;

    if ( QTextDrag::decode( a_event, text ) )
        insertItem( text );
  
}



While I do drag it simply copies the dragged element at last..

What the issue in this code..?

I tried ur ProjectView class with out doing any changes, but that also doesn't works for me...

Regards,
Mani
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This post has been edited 2 times, last edit by "Manivannan_1984" (Feb 28th 2007, 8:39am)

sunil.thaha

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8

Wednesday, February 28th 2007, 9:45am

RE: Drag & Drop in ListBox

What exactly are you trying to achieve here. The code I gave just demonstrates how the drag and drop works.

Manivannan_1984

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9

Wednesday, February 28th 2007, 9:54am

RE: Drag & Drop in ListBox

I want to implement drag&drop in QListBox... ie moving items(chaning positions of Items) in the list box using drag and drop...

I used same example which is available in the Qt-Assistant, but as I told you already, it simply copies items at the last index of list box..
[PHP]

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