C# graphics bounce on side of window

Question

I am trying to have bitmap reflect/bounce when it hits the sides of a window.

Basically, I want to initialise the bitmap to move (shown by BallSpeedX/Y). When it hits the top or bottom it should change direction (BallSpeedY should be inverted). Currently when the bitmap hits the wall, it changes its Y direction briefly before reverting to the original direction. Is there a way I can initialise the X and Y speed, but once it hits the wall keep the new direction (such as in a while loop)?

int BallSpeedX = 3;
int BallSpeedY = 5;

public void Draw(Window screen)
    {        
        _PlayerBitmap.Draw(X,Y);
        X += BallSpeedX;
       // Y += BallSpeedY;
        _PlayerBitmap.Draw(X,Y);

        if (Y < screen.Height)
        { //Off bottom
            Y += BallSpeedY *-1;
    
           _PlayerBitmap.Draw(X,Y);
        }

        if (Y > screen.Height)
        {   //Off top
            Y += BallSpeedY *-1;           
            _PlayerBitmap.Draw(X,Y);
        }        
    }

Answer 1

The speed is a 2D-vector, so whenever the "ball" hits an edge, you should change the sign of the related coordinate.

int BallSpeedX = 3;
int BallSpeedY = 5;
int ballWidth = 10;
int ballHeight = 10;

public void Draw(Window screen)
{        
    X += BallSpeedX;
    if (X <= 0) {
        BallSpeedX = -BallSpeedX;
        X = 0;
    }
    else if (X >= (screen.Width - ballWidth)) {
        BallSpeedX = -BallSpeedX;
        X = screen.Width - ballWidth;
    }

    /// (same for Y-coords)        
   
    _PlayerBitmap.Draw(X,Y);
}

This is a very simplified version, but I think it should be a good strarting point.