c# datagridview 打印只打一页，不能多页打印，请高手帮忙。
首先是一个类：


namespace schoolInformation
{

    public class Printer
    {
        private DataGridView dataview;
        private PrintDocument printDoc;
        //打印有效区域的宽度   
        int width;
        int height;
        int columns;
        double Rate;
        bool hasMorePage = false;
        int currRow = 0;
        int rowHeight = 20;
        //打印页数   
        int PageNumber;
        //当前打印页的行数   
        int pageSize = 20;
        //当前打印的页码   
        int PageIndex;

        private int PageWidth; //打印纸的宽度   
        private int PageHeight; //打印纸的高度   
        private int LeftMargin; //有效打印区距离打印纸的左边大小   
        private int TopMargin;//有效打印区距离打印纸的上面大小   
        private int RightMargin;//有效打印区距离打印纸的右边大小   
        private int BottomMargin;//有效打印区距离打印纸的下边大小   

        int rows;
      public Printer(DataGridView dataview, PrintDocument printDoc)
        {
            
            this.dataview = dataview;
            this.printDoc = printDoc;
            PageIndex = 0;
            //获取打印数据的具体行数   
            this.rows = dataview.RowCount;

            this.columns = dataview.ColumnCount;
            //判断打印设置是否是横向打印   
            if (!printDoc.DefaultPageSettings.Landscape)
            {

                PageWidth = printDoc.DefaultPageSettings.PaperSize.Width;
                PageHeight = printDoc.DefaultPageSettings.PaperSize.Height;