[Solved]Functions of the QRectF class



  • Greetings.

    I wanted to know if the values ​​returned by the functions:

    @
    QRectF::topLeft()
    QRect::topRight()
    QRectF::bottomleft()
    QRectF::bottomRight()
    @

    are calculated whenever these functions are invoked or are stored as internal attributes of the QRectF class.

    I have doubts about whether it is better to invoke those functions just once and store the returned values ​​(for future reference) or, on the contrary, it is best to invoke these functions whenever needed.

    Thanks in advance for any answers and / or suggestions.



  • As Qt is open-source, you can just have a look inside the code for yourself! I did it for you, and in qrect.h, we have:
    @
    inline QPointF topLeft() const { return QPointF(xp, yp); }
    inline QPointF bottomRight() const { return QPointF(xp+w, yp+h); }
    inline QPointF topRight() const { return QPointF(xp+w, yp); }
    inline QPointF bottomLeft() const { return QPointF(xp, yp+h); }
    @
    So there shouldn't be a problem...

    In general: DO NOT WORRY ABOUT PERFORMANCE TOO EARLY. Always measure it. Use profiling, and when you clearly identify a problem, pinpoint the exact spot and take care of the problem.



  • Thanks for the reply and advice


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