QT drag and drop - Creating a temporary QLabel using qobject_cast_问答_开发者

QT drag and drop - Creating a temporary QLabel using qobject_cast

开发者 https://www.devze.com 2023-02-07 07:13 出处：网络

I\'m trying to give a custom class that inherits from QLabel to be draggable. Towards that end, I\'m t开发者_Go百科rying to create a temporary copy of the class at the current mouse position using the

I'm trying to give a custom class that inherits from QLabel to be draggable. Towards that end, I'm t开发者_Go百科rying to create a temporary copy of the class at the current mouse position using the following code inside of the class' mousePressEvent:

QLabel *child = qobject_cast{QLabel*}(this->childAt(event->pos()));



NOTE: this line has carrots instead of brackets, but stack overflow interprets it and takes it out

if (!child)
    return;

The child is never created, and I can't figure out why. Any ideas?

If your code is within your QLabel-derived class, childAt() is not the right function. That would return a child widget contained within your label. It doesn't sound like that is what you are trying to do, but correct me if I am misunderstanding.

The object you want to copy is this, but "copy" can have many meanings in c++, and I am not sure exactly you are trying to do. You will probably have to implement it yourself, perhaps with a method called clone() that creates a new instance of your class and populates the values you need to reproduce.

I suspect, though, that there is a better way to implement the drag and drop functionality you are looking for without a copy.