.Net 使用HighCharts 导入图片到Excel

需求：数据统计报表使用到HighCharts显示各种图形：柱状图，饼图，点阵图等等，需要将数据表以及对应的图像导入到Excel中，方便打印。

解决方法： Excel导出采用NPOI，HighChart图像利用svg将图片写入到Excel中。

遇到的问题：图片模糊，图片清晰度与web页面相比差距很大。

        

 

明显可以看出，差别很大，无法达到要求，

实现此所采用的代码：

 var doc = new SvgDocument();
             XmlDocument xml = new XmlDocument();
             xml.LoadXml(this.chart_Hidden.Value);
             doc = SvgDocument.Open(xml);
             Bitmap mapImage = doc.Draw();
             byte[] buffer = NPOIExportExcelHelp.BitmapToBytes(mapImage);
             int pictureIdx = workBook.AddPicture(buffer, PictureType.JPEG);
             HSSFPatriarch patriarch = (HSSFPatriarch)sheet.CreateDrawingPatriarch();
             HSSFClientAnchor anchor = new HSSFClientAnchor(, , , , , , ,  );
             HSSFPicture pict = (HSSFPicture)patriarch.CreatePicture(anchor, pictureIdx);
             pict.Resize();

优化方案：

1 下载开源的.net导出文件： https://github.com/imclem/Highcharts-export-module-asp.net

利用此项目中的dll文件：itextsharp.dll,sharpPDF.dll,Svg.dll

2   借鉴文章：https://jucelin.com/highcharts_esport_net.html  中针对于CreateSvgDocument()方法的优化改造，优化图片的格式，

 /// <summary>
         /// Creates an SvgDocument from the SVG text string.
         /// </summary>
         /// <returns>An SvgDocument object.</returns>
         private SvgDocument CreateSvgDocument()
         {
             SvgDocument svgDoc;
             XmlDocument xml = new XmlDocument();
             xml.LoadXml(this.Svg);
             XmlNodeList nodeListAllg = xml.GetElementsByTagName("g");
             Dictionary<int, XmlNode[,]> dic = new Dictionary<int, XmlNode[,]>();
             int i = ;
             foreach (XmlNode xNod in nodeListAllg)
             {
                 i++;
                 XmlNode xmlvisibility = xNod.Attributes.GetNamedItem("class");
                 if (xmlvisibility != null && xmlvisibility.Value == "highcharts-series-group")
                 {
                     foreach (XmlNode xNod2 in xNod.ChildNodes)
                     {
                         i++;
                         XmlNode xmlvisibility1 = xNod2.Attributes.GetNamedItem("visibility");
                         if (xmlvisibility1 != null && xmlvisibility1.Value == "hidden")
                         {
                             XmlNode[,] xmln = new XmlNode[, ];
                             xmln[, ] = xNod;
                             xmln[, ] = xNod2;
                             dic.Add(i, xmln);
                         }
                     }
                 }
                 else if (xmlvisibility != null && xmlvisibility.Value == "highcharts-tooltip")
                 {
                     XmlNode[,] xmln = new XmlNode[, ];
                     xmln[, ] = xml.FirstChild;
                     xmln[, ] = xNod;
                     dic.Add(i, xmln);
                 }
             }
             foreach (KeyValuePair<int, XmlNode[,]> a in dic)
             {
                 a.Value[, ].RemoveChild(a.Value[, ]);
             }
             this.Svg = xml.OuterXml;
             // Create a MemoryStream from SVG string.
             using (MemoryStream streamSvg = new MemoryStream(
               Encoding.UTF8.GetBytes(this.Svg)))
             {
                 // Create and return SvgDocument from stream.
                 svgDoc = SvgDocument.Open(streamSvg);
             }
             // Scale SVG document to requested width.
             svgDoc.Transforms = new SvgTransformCollection();
             float scalar = (float)this.Width / (float)svgDoc.Width;
             svgDoc.Transforms.Add(new SvgScale(scalar, scalar));
             svgDoc.Width = new SvgUnit(svgDoc.Width.Type, svgDoc.Width * scalar);
             svgDoc.Height = new SvgUnit(svgDoc.Height.Type, svgDoc.Height * scalar);
             return svgDoc;
         }

 

3 利用第二步的方法，基本可以满足要求,生成的Exce图片效果如下

4 将以上方法整理封装成类库

 public class HightChartExport
     {
         /// <summary>
         /// 获取svg图片buffer，用于excel
         /// </summary>
         /// <param name="svgHtml"></param>
         /// <param name="width"></param>
         /// <param name="height"></param>
         /// <returns></returns>
         public static byte[] GetSvgDocumentByte(string svgHtml, int width, int height)
         {
             try
             {
                 if (string.IsNullOrEmpty(svgHtml))
                 {
                     return new byte[];
                 }
                 if (width ==  || height == )
                 {
                     return new byte[];
                 }
                 SvgDocument svgDocument = CreateSvgDocument(svgHtml, width, height);
                 return BitmapToBytes(svgDocument.Draw());
             }
             catch
             {
                 throw new Exception();
             }
         }
         private static SvgDocument CreateSvgDocument(string svgHtml, int width, int height)
         {
             SvgDocument svgDoc;
             XmlDocument xml = new XmlDocument();
             xml.LoadXml(svgHtml);
             XmlNodeList nodeListAllg = xml.GetElementsByTagName("g");
             Dictionary<int, XmlNode[,]> dic = new Dictionary<int, XmlNode[,]>();
             int i = ;
             foreach (XmlNode xNod in nodeListAllg)
             {
                 i++;
                 XmlNode xmlvisibility = xNod.Attributes.GetNamedItem("class");
                 if (xmlvisibility != null && xmlvisibility.Value == "highcharts-series-group")
                 {
                     foreach (XmlNode xNod2 in xNod.ChildNodes)
                     {
                         i++;
                         XmlNode xmlvisibility1 = xNod2.Attributes.GetNamedItem("visibility");
                         if (xmlvisibility1 != null && xmlvisibility1.Value == "hidden")
                         {
                             XmlNode[,] xmln = new XmlNode[, ];
                             xmln[, ] = xNod;
                             xmln[, ] = xNod2;
                             dic.Add(i, xmln);
                         }
                     }
                 }
                 else if (xmlvisibility != null && xmlvisibility.Value == "highcharts-tooltip")
                 {
                     XmlNode[,] xmln = new XmlNode[, ];
                     xmln[, ] = xml.FirstChild;
                     xmln[, ] = xNod;
                     dic.Add(i, xmln);
                 }
             }
             foreach (KeyValuePair<int, XmlNode[,]> a in dic)
             {
                 a.Value[, ].RemoveChild(a.Value[, ]);
             }
             svgHtml = xml.OuterXml;
             // Create a MemoryStream from SVG string.
             using (MemoryStream streamSvg = new MemoryStream(
               Encoding.UTF8.GetBytes(svgHtml)))
             {
                 // Create and return SvgDocument from stream.
                 svgDoc = SvgDocument.Open<SvgDocument>(streamSvg);
             }
             // Scale SVG document to requested width.
             svgDoc.Transforms = new SvgTransformCollection();
             float scalar = (float)width / (float)svgDoc.Width;
             svgDoc.Transforms.Add(new SvgScale(scalar, scalar));
             svgDoc.Width = new SvgUnit(svgDoc.Width.Type, svgDoc.Width * scalar);
             svgDoc.Height = new SvgUnit(svgDoc.Height.Type, svgDoc.Height * scalar);
             return svgDoc;
         }
         /// <summary>
         /// 读取图片
         /// </summary>
         /// <param name="Bitmap"></param>
         /// <returns></returns>
         private static byte[] BitmapToBytes(Bitmap Bitmap)
         {
             MemoryStream ms = null;
             try
             {
                 ms = new MemoryStream();
                 Bitmap.Save(ms, ImageFormat.Png);
                 byte[] byteImage = new Byte[ms.Length];
                 byteImage = ms.ToArray();
                 return byteImage;
             }
             catch (ArgumentNullException ex)
             {
                 throw ex;
             }
             finally
             {
                 ms.Close();
             }
         }
     }

5 调用方法如下：

 byte[] buffer = HightChartExport.GetSvgDocumentByte(this.chart_Pie.Value, Convert.ToInt32(chart_width.Value), Convert.ToInt32(chart_height.Value));
  int pictureIdx = workBook.AddPicture(buffer, PictureType.PNG);
  HSSFPatriarch patriarch = (HSSFPatriarch)sheet.CreateDrawingPatriarch();
  HSSFClientAnchor anchor = new HSSFClientAnchor(, , , , , rowIndex + , , );
  HSSFPicture pict = (HSSFPicture)patriarch.CreatePicture(anchor, pictureIdx);
   pict.Resize();

参考文章

https://github.com/imclem/Highcharts-export-module-asp.net

https://jucelin.com/highcharts_esport_net.html