为什么GetPageLabels的结果与Adobe Acrobat不同

Question

我在Adobe Acrobat X Pro中编辑pdf的页码。 Test PDF

• 结果：
  • 1- FrontCover
  • 2- FrontFold
  • 3-I
  • 4-II
  • 5-ⅲ
  • 6-1
  • 7-2
  • 8-3
  • 9-4
  • 10-5
  • 11 BackFold
  • 12后盖

但是GetPageLabels的这一结果是错的

• 页码：
  • 0-FrontCover1
  • 1- FrontFold1
  • 2- FrontFoldi
  • 3- FrontFoldii
  • 4- FrontFoldiii
  • 5- FrontFold1
  • 6- FrontFold2
  • 7-FrontFold3
  • 8 FrontFold4
  • 9 FrontFold5
  • 10 BackFold1
  • 11 BackCover1

C＃代码：

objLabels = PdfPageLabels.GetPageLabels(objReader); 
TextBox1.Text += "page number:" + Environment.NewLine; 
if (objLabels != null) { 
    for (i = 0; i <= objLabels.Length - 1; i++) { 
     TextBox1.Text += i + "-" + objLabels(i) + Environment.NewLine; 
    } 
} 

如何得到正确的结果像Adobe Acrobat X Pro？

Answer 1

PdfPageLabels.GetPageLabels(PdfReader)有一个小错误。当遇到一个新的标签页的字典没有P（前缀）项，它不重置当前prefix值：

int pagecount = 1; 
String prefix = ""; 
char type = 'D'; 
for (int i = 0; i < n; i++) { 
    if (numberTree.ContainsKey(i)) { 
     PdfDictionary d = (PdfDictionary)PdfReader.GetPdfObjectRelease(numberTree[i]); 
     if (d.Contains(PdfName.ST)) { 
      pagecount = ((PdfNumber)d.Get(PdfName.ST)).IntValue; 
     } 
     else { 
      pagecount = 1; 
     } 
     if (d.Contains(PdfName.P)) { 
      prefix = ((PdfString)d.Get(PdfName.P)).ToUnicodeString(); 
     } 
     if (d.Contains(PdfName.S)) { 
      type = ((PdfName)d.Get(PdfName.S)).ToString()[1]; 
     } 
     else { 
      type = 'e'; 
     } 
    } 
    ... 
} 

您可以在问题中添加以下else条款的if解决这个问题：

 if (d.Contains(PdfName.P)) { 
      prefix = ((PdfString)d.Get(PdfName.P)).ToUnicodeString(); 
     } 
     else 
     { 
      prefix = ""; 
     } 

蒙山这种变化，我得到我得到

page number: 
0 - FrontCover 
1 - FrontFold 
2 - i 
3 - ii 
4 - iii 
5 - 1 
6 - 2 
7 - 3 
8 - 4 
9 - 5 
10 - BackFold 
11 - BackCover 

PS：同样的问题出现在Java iText版本中，在ReadPageLabels.java中测试过。

Answer 2

谢谢你帮助解决我的问题， 这是我的完整程序。

public string[] ReadPageLabel(PdfReader objReader, int intPageCount) 
{ 
    PdfDictionary objDictionary ; 
    Dictionary<int, PdfObject> objTree ; 
    string[] arrLabels ; 
    int i ; 
    char chrLabelKind ; 
    string strLabelPrefix ; 
    int intLableNumber ; 
    //PdfPageLabels is wrong 
    //arrLabels = PdfPageLabels.GetPageLabels(objReader) 


    arrLabels = new string[intPageCount]; 

    if (objReader.Catalog.Get(PdfName.PAGELABELS) != null) { 
     objTree = PdfNumberTree.ReadTree(PdfReader.GetPdfObjectRelease(objReader.Catalog.Get(PdfName.PAGELABELS))); 

     chrLabelKind = 'D'; 
     strLabelPrefix = ""; 
     intLableNumber = 1; 
     for (i = 0; i <= intPageCount - 1; i++) { 
      if (objTree.ContainsKey(i)) { //if reset page number 
       objDictionary = PdfReader.GetPdfObjectRelease(objTree[i]); 
       //PdfName.S:Number Kind 
       if (objDictionary.Contains(PdfName.S)) { 
        chrLabelKind = ((PdfName)objDictionary.Get(PdfName.S)).ToString()(1); 
        //PdfName.S:/R,/r,/A,/a,/e,/D,ToString()(1)get alphabet of Index=1 
       } else { 
        chrLabelKind = 'e'; 
       } 
       //PdfName.P:Prefix 
       if (objDictionary.Contains(PdfName.P)) { 
        strLabelPrefix = ((PdfString)objDictionary.Get(PdfName.P)).ToUnicodeString();    
       } else { 
        strLabelPrefix = ""; 
       } 
       //PdfName.ST:Start Number 
       if (objDictionary.Contains(PdfName.ST)) { 
        intLableNumber = ((PdfNumber)objDictionary.Get(PdfName.ST)).IntValue; 
       } else { 
        intLableNumber = 1; 
       } 
      } 
      switch (chrLabelKind) { 
       case 'R': 
        //I,II,III 
        arrLabels[i] = strLabelPrefix + factories.RomanNumberFactory.GetUpperCaseString(intLableNumber); 
        break; 
       case 'r': 
        //i,ii,iii 
        arrLabels[i] = strLabelPrefix + factories.RomanNumberFactory.GetLowerCaseString(intLableNumber); 
        break; 
       case 'A': 
        //A,B,C 
        arrLabels[i] = strLabelPrefix + factories.RomanAlphabetFactory.GetUpperCaseString(intLableNumber); 
        break; 
       case 'a': 
        //a,b,c 
        arrLabels[i] = strLabelPrefix + factories.RomanAlphabetFactory.GetLowerCaseString(intLableNumber); 
        break; 
       case 'e': 
        //no number kind 
        arrLabels[i] = strLabelPrefix; 
        break; 
       default: 
        //1,2,3 
        arrLabels[i] = strLabelPrefix + intLableNumber; 
        break; 
      } 
      intLableNumber += 1; 

     } 
    } else { 
     for (i = 0; i <= intPageCount - 1; i++) { 
      arrLabels[i] = i + 1; 
     } 
    } 
    return arrLabels; 
}