Is there any better way to move a window?

Question

I am working on an application with Qt Framework for desktop. Since I remove every window decoration I had to implement the main window to receive move event from when the user click on it and move the mouse around.

I tried the following code but I am not satisfied. I wonder if there is any better way to this with more elegance.

QPoint* mouseOffset; //global variable that hold distance of the cursor from 
                       the top left corner of the window.

void ArianaApplication::mouseMoveEvent(QMouseEvent* event)
{
     move(event->screenPos().x() - mouseOffset->x(),
          event->screenPos().y() - mouseOffset->y());
}

void ArianaApplication::mousePressEvent(QMouseEvent*)
{
     mouseOffset = new QPoint(QCursor::pos().x() - pos().x(),
                              QCursor::pos().y() - pos().y());
}

Would you suggest me something else?

Lots of types in Qt can be handled like values, i.e. you should not be manually allocating memory for them. It's the compiler's job to do it. Every single `new` in your code should have a rationale behind it. I'd guess that 9 out of 10 `new`s in SO Qt questions are unnecessary. `QPoint` is a value type! — Kuba hasn't forgotten Monica, Mar 16 '18 at 20:42

score 8 · Accepted Answer · answered Mar 13 '18 at 01:57

The method is correct, but the implementation can be improved in the following points:

mouseOffset is not necessary to be a pointer, since you are creating dynamic memory unnecessarily and you have the responsibility to eliminate it.
It is not necessary to obtain each component, QPoint supports subtraction.

*.h

QPoint mouseOffset;

*.cpp

void ArianaApplication::mouseMoveEvent(QMouseEvent * event)
{
     move(event->globalPos() - mouseOffset);
}

void ArianaApplication::mousePressEvent(QMouseEvent * event)
{
     mouseOffset = event->globalPos() - frameGeometry().topLeft();
}

Is there any better way to move a window?

1 Answers1