问如何创建行数不总是相同的滚动列表？

EN

//Creating the scroll list: 

public List<Vector2> ScrolllistInitialRowPosYList = new List<Vector2>();
public List<Vector2> ScrolllistRowPosYList = new List<Vector2>();
Microsoft.Xna.Framework.Rectangle ScrollPointRectangle, tappRect, ScrollRectangle;
int ScrollLimitTopPosY = 200, ScrollLimitBottomPosY = 400, RowHeight = 60, ScrollPointStartPosY;
float ScrollAreaHeight, HeightallRows, ScrollSpeed;

ScrollPointStartPosY = ScrollLimitTopPosY;
ScrollPointRectangle = new Microsoft.Xna.Framework.Rectangle(500, ScrollPointStartPosY, ScrollPointSprite.Width, ScrollPointprite.Height);
tappRect = new Microsoft.Xna.Framework.Rectangle(-150, -100, 10, 10);
ScrollRectangle = new Microsoft.Xna.Framework.Rectangle(500, 300, ScrollRectangleSprite.Width, ScrollRectangleSprite.Height);

int FirstRowPosY = 0;
int NumberofRows = 13;
ScrollAreaHeight = ScrollLimitBottomPosY - ScrollLimitTopPosY;
int ListViewportHeight = 6 * RowHeight;
HeightallRows = NumberofRows * RowHeight - ListViewportHeight;

ScrollSpeed = HeightallRows / ScrollAreaHeight;

for (int i = 0; i <= NumberofRows - 1; i++)
{
     ScrolllistInitialRowPosYList.Add(new Vector2(500, FirstRowPosY));
     ScrolllistRowPosYList.Add(new Vector2(500, FirstRowPosY));                     
     FirstRowPosY += RowHeight;
}

//Updating gestures:

                    case GestureType.FreeDrag:
                    if (tappRect.Intersects(ScrollRectangle))
                    {
                        tappRect = new Microsoft.Xna.Framework.Rectangle((int)gs.Position.X, (int)gs.Position.Y, 10, 10);

                            if (gs.Delta.Y > 0)
                            {
                             if (ScrollPointRectangle.Y >= ScrollLimitTopPosY + 2)
                                ScrollPointRectangle = new Microsoft.Xna.Framework.Rectangle(500, ScrollPointRectangle.Y - 2, ScrollPointSprite.Width, ScrollPointSprite.Height);
                          else
                                ScrollPointRectangle = new Microsoft.Xna.Framework.Rectangle(500, ScrollLimitTopPosY, ScrollPointSprite.Width, ScrollPointSprite.Height);
                            }
                            else
                            {
                                if (gs.Delta.Y < 0)
                                {
                                    if (ScrollPointRectangle.Y <= ScrollLimitBottomPosY - 2)
                                      ScrollPointRectangle = new Microsoft.Xna.Framework.Rectangle(500, ScrollPointRectangle.Y + 2, ScrollPointSprite.Width, ScrollPointSprite.Height);
                                    else
                                      ScrollPointRectangle = new Microsoft.Xna.Framework.Rectangle(500, ScrollLimitBottomPosY, ScrollPointSprite.Width, ScrollPointSprite.Height);
                                }
                            }
                    }
                    break;

//Updating the scroll list after someone srolled up or down:

        for (int i = 0; i <= ScrolllistRowPosYList.Count - 1; i++)
        {
            int ScrollPosYCurrent = ScrollPointRectangle.Y;

            int ScrollPosYDifference = ScrollPosYCurrent - ScrollPointStartPosY;
            float RowPosYDifference = ScrollSpeed * ScrollPosYDifference;

            int RowInitialPosY = (int)ScrolllistInitialRowPosYList[i].Y;

            float RowCurrentPosY = RowInitialPosY - RowPosYDifference;

            ScrolllistRowPosYList[i] = new Vector2(ScrolllistRowPosYList[i].X, RowCurrentPosY);
        }