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 !