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TextSearch Class

TextSearch searches through a PDF document for a user-given search pattern. The current implementation supports both verbatim search and the search using regular expressions, whose detailed syntax can be found at: TextSearch also provides users with several useful search modes and extra information besides the found string that matches the pattern. TextSearch can either keep running until a matched string is found or be set to return periodically in order for the caller to perform any necessary updates (e.g., UI updates). It is also worth mentioning that the search modes can be changed on the fly while searching through a document. Possible use case scenarios for TextSearch include:
  • Guide users of a PDF viewer (e.g. implemented by PDFViewCtrl) to places where they are intersted in;
  • Find interested PDF documents which contain certain patterns;
  • Extract interested information (e.g., credit card numbers) from a set of files;
  • Extract Highlight information (refer to the Highlights class for details) from files for external use.
  • Since hyphens ('-') are frequently used in PDF documents to concatenate the two broken pieces of a word at the end of a line, for example "TextSearch is powerful for finding patterns in PDF files; yes, it is really pow- erful." a search for "powerful" should return both instances. However, not all end-of-line hyphens are hyphens added to connect a broken word; some of them could be "real" hyphens. In addition, an input search pattern may also contain hyphens that complicate the situation. To tackle this problem, the following conventions are adopted:
    1. When in the verbatim search mode and the pattern contains no hyphen, a matching string is returned if it is exactly the same or it contains end-of-line or start-of-line hyphens. For example, as mentioned above, a search for "powerful" would return both instances.
    2. When in verbatim search mode and the pattern contains one or multiple hyphens, a matching string is returned only if the string matches the pattern exactly. For example, a search for "pow-erful" will only return the second instance, and a search for "power-ful" will return nothing.
    3. When searching using regular expressions, hyphens are not taken care implicitly. Users should take care of it themselves. For example, in order to find both the "powerful" instances, the input pattern can be "pow-{0,1}erful".
For a full sample, please take a look at the TextSearch sample project.
   //... Initialize PDFNet ...
PDFDoc doc = new PDFDoc(filein);
int mode = TextSearch.e_whole_word | TextSearch.e_page_stop;
UString pattern("joHn sMiTh");
TextSearch txt_search = new TextSearch();

//PDFDoc doesn't allow simultaneous access from different threads. If this
//document could be used from other threads (e.g., the rendering thread inside
//PDFView/PDFViewCtrl, if used), it is good practice to lock it.
//Notice: don't forget to call doc.Unlock() to avoid deadlock.
txt_search.Begin( doc, pattern, mode, -1, -1 );
while ( true )
    TextSearch.ResultCode result = txt_search.Run();
    if ( result.GetCode() == TextSearchResult.e_found )
        Console.WriteLine("found one instance: " + result.GetResultStr());

//unlock the document to avoid deadlock.
Inheritance Hierarchy

Namespace:  pdftron.PDF
Assembly:  pdftron (in pdftron.dll) Version:
public sealed class TextSearch : IClosable

The TextSearch type exposes the following members.

Public methodTextSearch
Constructor and destructor.
Public methodBegin
Initialize for the search process. This should be called before starting the actual search. with method run().
Public methodClose
Public methodEquals
Determines whether the specified Object is equal to the current Object.
(Inherited from Object.)
Public methodGetCurrentPage
Retrieve the number of the current page that is searched in. If the returned value is -1, it indicates the search process has not been initialized (e.g., begin() is not called yet); if the returned value is 0, it indicates the search process has finished, and if the returned value is positive, it is a valid page number.
Public methodGetHashCode
Serves as a hash function for a particular type.
(Inherited from Object.)
Public methodGetMode
Retrieve the current search mode.
Public methodGetType
Gets the Type of the current instance.
(Inherited from Object.)
Public methodRun
Search the document and returns upon the following circumstances:
  • Reached the end of the document
  • Reached the end of a page (if set to return by specifying mode 'e_page_stop')
  • Found an instance matching the search pattern
Note that this method should be called in a loop in ordre to find all matching instances; in other words, the search is conducted in an incremental fashion.
Public methodSetMode
Set the current search mode. For example, the following code turns on the regular expression: TextSearch ts = new TextSearch(); ... int mode = ts.getMode(); mode |= TextSearch.e_reg_expression; ts.setMode(mode); ...
Public methodSetPattern
Sets the current search pattern. Note that it is not necessary to call this method since the search pattern is already set when calling the begin() method. This method is provided for users to change the search pattern while searching through a document.
Public methodSetRightToLeftLanguage
Tells TextSearch that the document reads from right to left.
Public methodToString
Returns a string that represents the current object.
(Inherited from Object.)
See Also