Drag and drop text displayed between QGLWidget

[QtVik]

How to drag and drop text displayed in one QGLWidget to another QGLWidget within a QT application?

I have re-implemented the methods dragMoveEvent, dropEvent, dragEnterEvent, dragLeaveEvent

and included setAcceptDrops(true) in the constructor also.

But still breakpoint is not hit in any of the above overridden methods even if i drag and drop between widgets.

[SGaist]

Hi,

Can you show the code you are using ?

[QtVik]

@SGaist :
Following is the code:

class MyView: public QGLWidget, public baseWidget
{
public:
MyView::MyView()
{
setAcceptDrops(true);
}
protected:
dragMoveEvent(QDragMoveEvent* event)
{
event->accept();
}
dragEnterEvent(QDragEnterEvent* event)
{
event->acceptProposedAction();
}
dragLeaveEvent(QDragLeaveEvent* event)
{
}
dropEvent(QDropEvent* event)
{
}
};

I am creating the views through mainWindow class derived from QMainWindow.
Please advice me how to write a dragEvent() while dragging within two different views.

[SGaist]

These are empty methods, you won't get custom drag and drop behaviour with just that.

Did you read the dedicated chapter about it in Qt's documentation ?

[QtVik]

@SGaist Thank you.
Will go through that and try..

[mrjj]

Hi
The
http://doc.qt.io/qt-5/qtwidgets-draganddrop-draggabletext-example.html
is pretty close to what you want.

[QtVik]

@mrjj Thank you.
Will try it and update.

[QtVik]

@SGaist @mrjj :

I was trying to use Q_DECLARE_METATYPE in drag object to copy the data from one widget to another.
The meta type is declared something like below:
Class MyView : public QGLWidget, public BaseWidget
{
public:
struct my_struct{
int m_var;
};
Q_DECLARE_METATYPE(my_struct)
};
But I am getting following errors:
error: explicit specialization in non-namespace scope ‘class MyView’
error: expected primary-expression before ‘>’ token reinterpret_cast< TYPE *>(quintptr(-1)));
error: expected ‘(’ before ‘my_struct’ Q_DECLARE_METATYPE(my_struct)

What is right way of declaring a Q_DECLARE_METATYPE ?

[mrjj]

Hi

I think it likes better if classes are not nested.

struct my_struct{
int m_var;
};
Q_DECLARE_METATYPE(my_struct)

Class MyView : public QGLWidget, public BaseWidget
{
public:
my_struct myvar;
};

[QtVik]

@mrjj : Thank you! you are absolutely right :)

One more query is how to handle mouse events when drag object is used ?
drag object seems to block all the mouse events.

I have created a drag object inside mousePressEvent() . Wanted to copy the string list from one widget to another.
I wanted to handle dropping of QList in mouseReleaseEvent() but as soon as drag object is created it blocks all mouse events.

[mrjj]

@QtVik
Super.

Regarding drag & drop.
You should fully use the drag system to do so.
http://doc.qt.io/qt-5/dnd.html
http://doc.qt.io/qt-5/qdropevent.html

Here it drops pictures.
http://doc.qt.io/qt-5/qtwidgets-draganddrop-puzzle-example.html
you can drop anything u like this way.

[QtVik]

@mrjj Thank you ! will try that and update..

[QtVik]

Hi @mrjj @SGaist : Thank you for the inputs. It worked !