C#结合html2canvas切割图片并导出到PDF

CREATE PROCEDURE CCDN_getTableDetail 
  @tablename nvarchar(50)
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;
SELECT
    表名=convert(nvarchar(50),case when a.colorder=1 then d.name else '' end),
    表说明=convert(nvarchar(50),case when a.colorder=1 then isnull(f.value,'') else '' end),
    字段序号=convert(nvarchar(50),a.colorder),
    字段名=convert(nvarchar(50),a.name),
    字段说明=convert(nvarchar(50),isnull(g.[value],'')),
    标识=convert(nvarchar(50),case when COLUMNPROPERTY(a.id,a.name,'IsIdentity')=1 then '√'else '' end),
    主键=convert(nvarchar(50),case when exists(SELECT 1 FROM sysobjects where xtype='PK' and name in (
      SELECT name FROM sysindexes WHERE indid in(
       SELECT indid FROM sysindexkeys WHERE id = a.id AND colid=a.colid
       ))) then '√' else '' end),
    类型=convert(nvarchar(50),b.name),
    长度=convert(nvarchar(50),COLUMNPROPERTY(a.id,a.name,'PRECISION')),
    占用字节数=convert(nvarchar(50),a.length),
    小数位数=convert(nvarchar(50),isnull(COLUMNPROPERTY(a.id,a.name,'Scale'),0)),
    允许空=convert(nvarchar(50),case when a.isnullable=1 then 'NULL'else 'NOT NULL' end),
    默认值=convert(nvarchar(50),isnull(e.text,''))
    FROM syscolumns a
    left join systypes b on a.xtype=b.xusertype
    inner join sysobjects d on a.id=d.id and d.xtype='U' and d.name<>'dtproperties'
    left join syscomments e on a.cdefault=e.id
    left join sys.extended_properties g on a.id=g.major_id and a.colid=g.minor_id
    left join sys.extended_properties f on d.id=f.major_id and f.minor_id =0
    where d.name=@tablename
    order by a.id,a.colorder
END

        object rv2 = GetDataSet(sql, paras,CommandType.StoredProcedure);
        DataSet ds = (DataSet)rv2;
        DataTable dt = ds.Tables[0];
        q_dbgrid.AllowPaging = true;
        q_dbgrid.PagerStyle.Visible = false;
        q_dbgrid.PageSize = 1000;
 
        q_dbgrid.DataSource = ds;
        q_dbgrid.DataBind();

<script src="https://cdnjs.cloudflare.com/ajax/libs/html2canvas/1.3.2/html2canvas.min.js"></script>

<script language="javascript" type="text/javascript">
 
window.onload = function () {
    var canvas = document.getElementById("myCanvas")
 
 
    html2canvas(document.getElementById("q_dbgrid")).then(canvas => {
    document.getElementById("myCanvas").appendChild(canvas); // 将生成的canvas添加到页面上
    var image = canvas.toDataURL("image/jpeg");
    document.getElementById("ds").value = image;
 
  });
 
}
</script>

public bool Base64StringToImage(string strbase64, string outputFilename)
{
 
       byte[] arr = Convert.FromBase64String(strbase64);
       MemoryStream ms = new MemoryStream(arr);
       System.Drawing.Image img = System.Drawing.Image.FromStream(ms);
       img.Save(outputFilename);
       img.Dispose();
       if (File.Exists(outputFilename))
       {
           return true;
       }
 
       return false;
}

string outjpgpath = "D:\\testPDF\\";
string filename="D:\\test.jpg";
string base64Data = ds.Text.Trim().Replace("data:image/jpeg;base64,", "");
Base64StringToImage(base64Data, filename);
 
System.Drawing.Bitmap sbitmap = new System.Drawing.Bitmap(filename);
int out_width = sbitmap.Width;
int ref_height = 1000; int com_height = sbitmap.Height;
int hCount =sbitmap.Height<ref_height?1:sbitmap.Height % ref_height==0?sbitmap.Height/ref_height:sbitmap.Height/ref_height+1;
int out_top = 0;
int out_height = ref_height;
        
for (int i = 1; i <= hCount; i++)
{
     if (i == 1) { out_top = 0; } else { out_top = ref_height * (i - 1) + 1; }
     out_height = com_height < ref_height ? System.Math.Abs(com_height)-1 : ref_height;
     com_height -= ref_height;
     System.Drawing.Bitmap dbitmap = sbitmap.Clone(new System.Drawing.RectangleF(0, out_top, sbitmap.Width, out_height), System.Drawing.Imaging.PixelFormat.Format24bppRgb);
     string f = "test" + ("0000" + i.ToString()).PadLeft(4) + ".jpg";
     dbitmap.Save(outjpgpath + f);
     dbitmap.Dispose();
}
sbitmap.Dispose();