Accepting mouse drag-and-drop events

In this project example, if you drag and drop a .wav file on a SoundEffectWidget, you can change the sound being played. The constructor of SoundEffectWidget performs a specific task to allow you to drag and drop:

setAcceptDrops(true); 

We can now override the drag-and-drop callbacks. Let's start with the dragEnterEvent() function:

//SoundEffectWidget.h 
class SoundEffectWidget : public QWidget 
{ 
... 
protected: 
    void dragEnterEvent(QDragEnterEvent* event) override; 
... 
}; 
 
//SoundEffectWidget.cpp 
void SoundEffectWidget::dragEnterEvent(QDragEnterEvent* event) 
{ 
    if (event->mimeData()->hasFormat("text/uri-list")) { 
        event->acceptProposedAction(); 
    } 
}

The dragEnterEvent() function is called each time the user drags an object on the widget. In our case, we only want to allow dragging and...