PDFTron pdfnet-node

Class: TextSearch

PDFNet. TextSearch

new TextSearch()

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: http://www.boost.org/doc/libs/release/libs/regex/doc/html/boost_regex/syntax/perl_syntax.html 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. Note: - 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: a)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. b)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. c)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". A sample use case (in C++): 
//... Initialize PDFNet ...
PDFDoc doc(filein);
doc.InitSecurityHandler();
int page_num;
char buf[32];
UString result_str, ambient_string;
Highlights hlts;
TextSearch txt_search;
TextSearch::Mode mode = TextSearch::e_whole_word | TextSearch::e_page_stop;
UString pattern( "joHn sMiTh" );

//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.
doc.Lock(); 

txt_search.Begin( doc, pattern, mode );
while ( true )
{
	   SearchResult result = code = txt_search.Run(page_num, result_str, ambient_string, hlts );
	   if ( code == TextSearch::e_found )
	   {
		   result_str.ConvertToAscii(buf, 32, true);
		   cout << "found one instance: " << char_buf << endl;
	   }
	   else
	   {
		   break;
	   }
}

//unlock the document to avoid deadlock.
doc.UnLock();
For a full sample, please take a look at the TextSearch sample project.

Extends

Members

<static> Mode

Type:
  • number
Properties:
Name Type Description
e_reg_expression number
e_case_sensitive number
e_whole_word number
e_search_up number
e_page_stop number
e_highlight number
e_ambient_string number

<static> ResultCode

Type:
  • number
Properties:
Name Type Description
e_done number
e_page number
e_found number

Methods

<static> create()

Constructor and destructor.
Returns:
A promise that resolves to an object of type: "PDFNet.TextSearch"
Type
Promise.<PDFNet.TextSearch>

begin(doc, pattern, mode [, start_page] [, end_page])

Initialize for search process. This should be called before starting the actual search with method Run().
Parameters:
Name Type Argument Description
doc PDFNet.PDFDoc | PDFNet.SDFDoc | PDFNet.FDFDoc the PDF document to search in.
pattern string the pattern to search for. When regular expression is used, it contains the expression, and in verbatim mode, it is the exact string to search for.
mode number the mode of the search process.
start_page number <optional>
 the start page of the page range to search in. The default value is -1 indicating the range starts from the first page.
end_page number <optional>
 the end page of the page range to search in. The default value is -1 indicating the range ends at the last page.
Returns:
A promise that resolves to true if the initialization has succeeded.
Type
Promise.<boolean>

destroy()

Destructor
Inherited From:
Returns:
Type
Promise.<void>

getCurrentPage()

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.
Returns:
A promise that resolves to the current page number.
Type
Promise.<number>

getMode()

Retrieve the current search mode.
Returns:
A promise that resolves to the current search mode.
Type
Promise.<number>

run()

Runs a search on the document for a certain string. Make sure to call TextSearch.begin(doc, pattern, mode) with the proper parameters before calling TextSearch.run() The resolved object that TextSearch.run() returns contains the following objects: page_num - The number of the page with the match out_str - The string that matches the search parameter ambient_str - The ambient string of the found string (computed only if e_ambient_string is set) highlights - The Highlights info associated with the match (computed only if 'e_highlight' is set) code - Number representing the status of the search. - 0 - e_done, reached end of document. - 1 - e_page, reached end of page. (if set to return by specifying mode 'e_page_stop') - 2 - e_found, found an instance matching the search pattern
Returns:
A promise that resolves to an object containing the page_num, out_str ambient_str, highlights, and result code.
Type
Promise.<any>

setAmbientLettersAfter(ambient_letters_after)

Sets the maximum number of ambient string letters after the search term (default: 70). This should be called before starting the actual search with method Run().
Parameters:
Name Type Description
ambient_letters_after number - maximum number of letters.
Returns:
Type
Promise.<void>

setAmbientLettersBefore(ambient_letters_before)

Sets the maximum number of ambient string letters before the search term (default: 30). This should be called before starting the actual search with method Run().
Parameters:
Name Type Description
ambient_letters_before number - maximum number of letters.
Returns:
Type
Promise.<void>

setAmbientWordsAfter(ambient_words_after)

Sets the maximum number of ambient string words after the search term (default: 10). This should be called before starting the actual search with method Run().
Parameters:
Name Type Description
ambient_words_after number - maximum number of words.
Returns:
Type
Promise.<void>

setAmbientWordsBefore(ambient_words_before)

Sets the maximum number of ambient string words before the search term (default: 1). This should be called before starting the actual search with method Run().
Parameters:
Name Type Description
ambient_words_before number - maximum number of words.
Returns:
Type
Promise.<void>

setMode(mode)

Set the current search mode. For example, the following code turns on the regular expressions: TextSearch ts; ... TextSearch::Mode mode = ts.GetMode(); mode |= TextSearch::e_reg_expression; ts.SetMode(mode); ...
Parameters:
Name Type Description
mode number the search mode to set.
Returns:
Type
Promise.<void>

setOCGContext(ctx)

Sets the Optional Content Group (OCG) context that should be used when processing the document. This function can be used to change the current OCG context. Optional content (such as PDF layers) will be selectively processed based on the states of optional content groups in the given context.
Parameters:
Name Type Description
ctx PDFNet.OCGContext Optional Content Group (OCG) context, or NULL if TextSearch should process all content on the page.
Returns:
Type
Promise.<void>

setPattern(pattern)

Set 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.
Parameters:
Name Type Description
pattern string the search pattern to set.
Returns:
A promise that resolves to true if the setting has succeeded.
Type
Promise.<boolean>

setRightToLeftLanguage(flag)

Tells TextSearch that language is from right to left.
Parameters:
Name Type Description
flag boolean Set to true if the language is right to left.
Returns:
Type
Promise.<void>

takeOwnership()

Take the ownership of this object, so that PDFNet.runWithCleanup won't destroy this object.
Inherited From:
Returns:
Type
void