C# 切割图片

传入原图，其实坐标点，切割的图像大小，切割图片

/// <summary>
/// 切割图片
/// </summary>
/// <param name="bit">原图</param>
/// <param name="StartX">起始坐标x</param>
/// <param name="StartY">起始坐标y</param>
/// <param name="iWidth">切割宽度</param>
/// <param name="iHeight">切割高度</param>
/// <returns></returns>
public static Bitmap CutImage(Bitmap bit, int StartX, int StartY, int iWidth, int iHeight)
{
    if (bit == null)
    {
        return null;
    }
    int w = bit.Width;
    int h = bit.Height;
    if (StartX >= w || StartY >= h)
    {
        return null;
    }
    if (StartX + iWidth > w)
    {
        iWidth = w - StartX;
    }
    if (StartY + iHeight > h)
    {
        iHeight = h - StartY;
    }
    try
    {
        //此处输出为24位色,可更改为其他位深
        Bitmap bmpOut = new Bitmap(iWidth, iHeight, PixelFormat.Format24bppRgb);
        Graphics g = Graphics.FromImage(bmpOut);
        g.DrawImage(bit, new Rectangle(0, 0, iWidth, iHeight), new Rectangle(StartX, StartY, iWidth, iHeight), GraphicsUnit.Pixel);
        g.Dispose();
        return bmpOut;
    }
    catch
    {
        return null;
    }
}