scrolling

Hello,

I have some troubles with scrolling. I have a picture box, and I would like to be able to zoom and scroll with a combination of mouse whell + ctrl/alt. The zooming part works fine. I was able to get the key controls, but I have troubles moving the scrollbars. I tried to use the HorizontalScroll properties, the value is changed fine when I do the required combination, but nothing happens on the main window... Here is the code I have. The windows form has autoscroll set to false.

        protected override void OnMouseWheel(MouseEventArgs mea)
        {
            if (ctrlDown && !shiftDown && pictureBox1.Image!=null)
            {
                // If the mouse wheel is moved forward (Zoom in)
                if (mea.Delta > 0 && zoomValue <= 5)
                {
                    zoomValue += 0.2;

                    pictureBox1.Width = (int)(pictureBox1.Width * 1.25);
                    pictureBox1.Height = (int)(pictureBox1.Height * 1.25);
                    //pictureBox1.Top = (int)(mea.Y - 1.25 * (mea.Y - pictureBox1.Top));
                    //pictureBox1.Left = (int)(mea.X - 1.25 * (mea.X - pictureBox1.Left));

                    pictureBox1.Image = PictureBoxZoom(bmpPictureBox, zoomValue);

                }
                //Zoom out
                else if (mea.Delta < 0 && zoomValue > 0.8)
                {
                    zoomValue -= 0.2;

                    pictureBox1.Width = (int)(pictureBox1.Width / 1.25);
                    pictureBox1.Height = (int)(pictureBox1.Height / 1.25);
                    //pictureBox1.Top = (int)(mea.Y - 0.80 * (mea.Y - pictureBox1.Top));
                    //pictureBox1.Left = (int)(mea.X - 0.80 * (mea.X - pictureBox1.Left));

                    pictureBox1.Image = PictureBoxZoom(bmpPictureBox, zoomValue);
                }
            }
            else if (shiftDown && !ctrlDown && pictureBox1.Image != null)
            {
                if (HorizontalScroll.Value + System.Math.Sign(mea.Delta)*10 < HorizontalScroll.Minimum)
                { HorizontalScroll.Value = HorizontalScroll.Minimum; }
                else if (HorizontalScroll.Value + System.Math.Sign(mea.Delta) * 10 > HorizontalScroll.Maximum)
                { HorizontalScroll.Value = HorizontalScroll.Maximum; }
                else { HorizontalScroll.Value += System.Math.Sign(mea.Delta) * 10; }
            }
            Refresh();
        }