Objective-C Requires Chilkat v11.7.0+

Clipped, Off-Page and White-on-White Text in PDF Extraction

See more PDF Text Extraction Examples

Demonstrates the "clippedText", "offPageText" and "obscuredText" filters. Text that a reader never sees - hidden by a clipping path, outside the crop box, or drawn in the same color as the box beneath it - is excluded by default, and the quality report notes what was skipped. Each kind can be included. Objective-C

#import <CkoPdf.h>
#import <CkoJsonObject.h>

BOOL success = NO;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  The PDF used in this example is available at hidden_text.pdf

CkoPdf *pdf = [[CkoPdf alloc] init];
success = [pdf LoadFile: @"qa_data/pdf/hidden_text.pdf"];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

CkoJsonObject *json = [[CkoJsonObject alloc] init];
CkoJsonObject *jsonOut = [[CkoJsonObject alloc] init];

//  The page has a visible paragraph plus three hidden lines: one drawn outside its clipping
//  rectangle, one below the crop box, and one in white on a white box.
success = [pdf ExtractText: @"text" jsonIn: json jsonOut: jsonOut];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

NSLog(@"%@",@"---- default ----");
NSLog(@"%@",[jsonOut StringOf: @"text"]);

//  The quality report says what was left out.
int i = 0;
int count_i = [[jsonOut SizeOfArray: @"quality.pages[0].issues"] intValue];
while (i < count_i) {
    jsonOut.I = [NSNumber numberWithInt: i];
    NSLog(@"%@%@",@"issue: ",[jsonOut StringOf: @"quality.pages[0].issues[i].code"]);
    i = i + 1;
}

//  Include everything.
[json UpdateString: @"clippedText" value: @"include"];
[json UpdateString: @"offPageText" value: @"include"];
[json UpdateString: @"obscuredText" value: @"include"];
success = [pdf ExtractText: @"text" jsonIn: json jsonOut: jsonOut];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

NSLog(@"%@",@"---- clippedText, offPageText, obscuredText: include ----");
NSLog(@"%@",[jsonOut StringOf: @"text"]);

//  Sample output:

//  ---- default ----
//  Visible Text
//  
//  This paragraph is visible. The page also carries three kinds of text a reader never sees.
//  
//  End of the visible text.
//  issue: obscuredTextSkipped
//  issue: clippedTextSkipped
//  ---- clippedText, offPageText, obscuredText: include ----
//  Visible Text
//  
//  This paragraph is visible. The page also carries three kinds of text a reader never sees.
//  
//  CLIPPED: this line is drawn outside its clipping rectangle.
//  
//  OBSCURED: this line is white on a white box.
//  
//  End of the visible text.
//  
//  OFFPAGE: this line sits below the crop box.