PdfiumViewer组件扩展(Pdfium.Net.Free)--注解

项目地址：

Pdfium.Net：https://github.com/1000374/Pdfium.Net

PdfiumViewer：https://github.com/1000374/PdfiumViewer

pdf的注解分很多类型，请查看以下枚举值：

  public enum FpdfAnnotSubtypes
  {
      //Unknown annotation.
      UNKNOWN = 0,
      //Text annotation type.
      TEXT = 1,
      //Link annotation type.
      LINK = 2,
      //Free text annotation type.
      FREETEXT = 3,
      //Line annotation type.
      LINE = 4,
      //Square annotatotion type.
      SQUARE = 5,
      //Circle annotation type.
      CIRCLE = 6,
      //Polygon annotation type.
      POLYGON = 7,
      //Plyline annotation type.
      POLYLINE = 8,
      //Highlight annotation type.
      HIGHLIGHT = 9,
      //Underline annotation type.
      UNDERLINE = 10,
      //Squiggle annotation type.
      SQUIGGLY = 11,
      //Strikeout annotation type.
      STRIKEOUT = 12,
      //Rubber stamp annotation type.
      STAMP = 13,
      //Caret annotation type.
      CARET = 14,
      //Ink annotation type.
      INK = 15,
      //Popup annotation type.
      POPUP = 16,
      //File attachment annotation type.
      FILEATTACHMENT = 17,
      //Sound annotation type.
      SOUND = 18,
      //Movie annotation type.
      MOVIE = 19,
      //Widget annotation type.
      WIDGET = 20,
      //Screen annotation type.
      SCREEN = 21,
      //Printer mark annotation type.
      PRINTERMARK = 22,
      //Trap network annotation type.
      TRAPNET = 23,
      //Watermark annotation type.
      WATERMARK = 24,
      THREED = 25,
      //Rich media annotation type
      RICHMEDIA = 26,
      XFAWIDGET = 27,
      REDACT = 28

  }

　　

可通过封装的方法获取常用的注解：

 var pathPdf = "./Pdfium.NetTests/resources/annotation_highlight_long_content.pdf";
 using (var doc = PdfDocument.Load(new MemoryStream(File.ReadAllBytes(pathPdf))))
 {
     var page0 = doc.Pages[0];
     var links = page0.GetPageLinks();
 }

 

也可通过以下方法自行遍历获取，此代码为示例代码、在pdf预览中很多交互未实现或者合并实现,比如填充（WIDGET）pdf等交互，感兴趣的 可以自行研究

  var pathPdf = "./Pdfium.NetTests/resources/annotation_highlight_long_content.pdf";
  using (var doc = PdfDocument.Load(new MemoryStream(File.ReadAllBytes(pathPdf))))
  {
      var page0 = doc.Pages[0];
      var pageText0 = page0.PageText;
      var form = doc.PdfForm;
      var annotCount = page0.PageGetAnnotCount();
      for (int i = 0; i < annotCount; i++)
      {
          var annot = page0.PageGetAnnot(i);
          var subType = annot.Subtype;
          var rect = annot.Rect;
          //无用
          var flag = annot.Flags;
          var boo = annot.IsSupportedSubtype(subType);
          switch (subType)
          {
              case FpdfAnnotSubtypes.HIGHLIGHT:
                  {
                      var higthLight = new AnnotData();
                      var keys = new string[] { FpdfAnnotationKeys.kAuthorKey, FpdfAnnotationKeys.kContents };
                      foreach (var key in keys)
                      {
                          var types = annot.GetValueType(key);
                          switch (types)
                          {
                              case FpdfObjectTypes.FPDF_OBJECT_STRING:
                                  if (key.Equals(FpdfAnnotationKeys.kAuthorKey))
                                      higthLight.Author = annot.GetStringValue(key);
                                  else
                                      higthLight.Content = annot.GetStringValue(key);
                                  break;
                              case FpdfObjectTypes.FPDF_OBJECT_NUMBER:
                                  if (annot.GetNumberValue(key, out float values))
                                  {
                                      if (key.Equals(FpdfAnnotationKeys.kAuthorKey))
                                          higthLight.Author = values.ToString();
                                      else
                                          higthLight.Content = values.ToString();
                                  }
                                  break;
                          }
                      }
                      if (annot.GetColor(FpdfAnnotColorType.Color, out uint r, out uint g, out uint b, out uint a))
                          higthLight.BackColor = Color.FromArgb((int)a, (int)r, (int)g, (int)b);
                      var attcount = annot.AttachmentPointsCount;
                      for (int j = 0; j < (int)attcount; j++)
                      {
                          var quad_points = new FS_QUADPOINTSF();
                          if (annot.GetAttachmentPoints((ulong)j, quad_points))
                          {

                          }
                      }

                      var index = pageText0.GetCharIndexAtPos(rect.Left, rect.Top, Math.Abs(rect.Right - rect.Left), Math.Abs(rect.Top - rect.Bottom));
                      var fontName = pageText0.GetFontInfo(index, out FpdfFxfontFlags flags);
                      var fontSize = pageText0.GetFontSize(index);
                      higthLight.FontName = fontName;
                      higthLight.FontSize = fontSize;

                  }
                  break;
              case FpdfAnnotSubtypes.LINK:
                  {
                      var flink = annot.GetLink();
                      var action = flink.GetAction();
                      var acType = action.GetActionType();
                      switch (acType)
                      {
                          case FpdfActionTypes.UNSUPPORTED:
                              {
                                  var dest = doc.LinkGetDest(flink);
                                  var targetPage = doc.DestGetDestPageIndex(dest);
                                  var uri = doc.ActionGetURIPath(action);
                              }
                              break;
                          case FpdfActionTypes.GOTO:
                              {
                                  var dest = doc.ActionGetDest(action);
                                  var targetPage = doc.DestGetDestPageIndex(dest);
                                  var uri = doc.ActionGetURIPath(action);

                              }
                              break;
                          case FpdfActionTypes.REMOTEGOTO:
                              break;
                          case FpdfActionTypes.URI:
                              {
                                  var uri = doc.ActionGetURIPath(action);

                              }
                              break;
                          case FpdfActionTypes.LAUNCH:
                              {
                                  var filePath = action.GetFilePath();
                                  // new RectangleF(rect.Left, rect.Top, rect.Right - rect.Left, rect.Bottom - rect.Top)
                              }
                              break;
                          case FpdfActionTypes.EMBEDDEDGOTO:
                              {
                                  var dest = doc.ActionGetDest(action);
                                  var view = dest.GetDestView(out uint paraNum, out float paras);
                                  var filePath = action.GetFilePath();
                              }
                              break;
                      }
                  }
                  break;
              case FpdfAnnotSubtypes.WIDGET:
                  {
                      var formflag = form.AnnotGetFormFieldFlags(annot);
                      var formName = form.AnnotGetFormFieldName(annot);
                      var formValue = form.AnnotGetFormFieldValue(annot);
                      var fontsize = form.AnnotGetFontSize(annot);
                      var optionCount = form.AnnotGetOptionCount(annot);
                      for (int ni = 0; ni < optionCount; ni++)
                      {
                          var lable = form.AnnotGetOptionLabel(annot, ni);
                          var iselect = form.AnnotIsOptionSelected(annot, ni);
                      }
                  }
                  break;
              case FpdfAnnotSubtypes.POPUP:
                  {
                      // Attempting to retrieve |annot|'s "IRT"-linked annotation would fail,
                      // since "IRT" is not a key in |annot|'s dictionary.
                      var kIRTKey = "IRT";
                      if (annot.HasKey(kIRTKey))
                      {
                          var linked = annot.GetLinkedAnnot(kIRTKey);
                      }
                      if (annot.HasKey(FpdfAnnotationKeys.kP))
                      {
                          var types = annot.GetValueType(FpdfAnnotationKeys.kP);
                          switch (types)
                          {
                              case FpdfObjectTypes.FPDF_OBJECT_STRING:
                                  var strValue = annot.GetStringValue(FpdfAnnotationKeys.kP);
                                  break;
                              case FpdfObjectTypes.FPDF_OBJECT_NUMBER:
                                  var numValue = annot.GetNumberValue(FpdfAnnotationKeys.kP, out float values);
                                  break;
                          }
                      }
                  }
                  break;
              case FpdfAnnotSubtypes.SQUARE:
                  break;
          }
      }

  }
    

　　

注解预览展示：现在交互支持打开url、页面跳转、打开内置链接、鼠标悬浮标注展示注释