How to know if a rectangle in xna is moving up or down

Question

I'm developing a gui for my game using monogame, and im having hard times trying to figure out how

to implement a chat system,almost everything is pretty much done except for the scroller of the

chat window, so the scoller is a rectangle with an image, if i click on it and drag it will follow

the mouse Y position, i wanted to know how can i determine if the scoller is going up or down ,

positive or negative?

here it is the code:

 Rectangle area3 = _chatScrollBoxScrollAreaRect;

        if (area3.Contains(mousePosition))
        {
            if (mouseState.LeftButton == ButtonState.Pressed)
            {
                if (mousePosition.Y < (area3.Y + area3.Height) - 40)
                {
                    scroll = true;
                    _chatScrollerRect.Y = mousePosition.Y;

                }
            }

any help is greatly appreciate!! Kind regards, Romulo Romero

Answer 1

Keep the old position of mouse.Y in a variable then check if mouse.Y is less than the variable. If it is less than the variable then the scroll is moving upwards. Else it is moving down.