pdf - Java: Apache PDFbox Extract highlighted text

Question

I am using Apache PDFbox library to extract the the highlighted text (i.e., with yellow background) from a PDF file. I am totally new to this library and don't know which class from it to be used for this purpose. So far I have done extraction of text from comments using below code.

PDDocument pddDocument = PDDocument.load(new File("test.pdf"));
    List allPages = pddDocument.getDocumentCatalog().getAllPages();
    for (int i = 0; i < allPages.size(); i++) {
    int pageNum = i + 1;
    PDPage page = (PDPage) allPages.get(i);
    List<PDAnnotation> la = page.getAnnotations();
    if (la.size() < 1) {
    continue;
    }
    System.out.println("Total annotations = " + la.size());
    System.out.println("
Process Page " + pageNum + "...");
    // Just get the first annotation for testing
    PDAnnotation pdfAnnot = la.get(0); 
    System.out.println("Getting text from comment = " + pdfAnnot.getContents());

Now I need to get the highlighted text, any code example will be highly appreciated.

Answer 1

I Hope this answer help everyone who is facing the same problem.

// PDF32000-2008
// 12.5.2 Annotation Dictionaries
// 12.5.6 Annotation Types
// 12.5.6.10 Text Markup Annotations
@SuppressWarnings({ "unchecked", "unused" })
public ArrayList<String> getHighlightedText(String filePath, int pageNumber) throws IOException {
    ArrayList<String> highlightedTexts = new ArrayList<>();
    // this is the in-memory representation of the PDF document.
    // this will load a document from a file.
    PDDocument document = PDDocument.load(filePath);
    // this represents all pages in a PDF document.
    List<PDPage> allPages =  document.getDocumentCatalog().getAllPages();
    // this represents a single page in a PDF document.
    PDPage page = allPages.get(pageNumber);
    // get  annotation dictionaries
    List<PDAnnotation> annotations = page.getAnnotations();

    for(int i=0; i<annotations.size(); i++) {
        // check subType 
        if(annotations.get(i).getSubtype().equals("Highlight")) {
            // extract highlighted text
            PDFTextStripperByArea stripperByArea = new PDFTextStripperByArea();

            COSArray quadsArray = (COSArray) annotations.get(i).getDictionary().getDictionaryObject(COSName.getPDFName("QuadPoints"));
            String str = null;

            for(int j=1, k=0; j<=(quadsArray.size()/8); j++) {

                COSFloat ULX = (COSFloat) quadsArray.get(0+k);
                COSFloat ULY = (COSFloat) quadsArray.get(1+k);
                COSFloat URX = (COSFloat) quadsArray.get(2+k);
                COSFloat URY = (COSFloat) quadsArray.get(3+k);
                COSFloat LLX = (COSFloat) quadsArray.get(4+k);
                COSFloat LLY = (COSFloat) quadsArray.get(5+k);
                COSFloat LRX = (COSFloat) quadsArray.get(6+k);
                COSFloat LRY = (COSFloat) quadsArray.get(7+k);

                k+=8;

                float ulx = ULX.floatValue() - 1;                           // upper left x.
                float uly = ULY.floatValue();                               // upper left y.
                float width = URX.floatValue() - LLX.floatValue();          // calculated by upperRightX - lowerLeftX.
                float height = URY.floatValue() - LLY.floatValue();         // calculated by upperRightY - lowerLeftY.

                PDRectangle pageSize = page.getMediaBox();
                uly = pageSize.getHeight() - uly;

                Rectangle2D.Float rectangle_2 = new Rectangle2D.Float(ulx, uly, width, height);
                stripperByArea.addRegion("highlightedRegion", rectangle_2);
                stripperByArea.extractRegions(page);
                String highlightedText = stripperByArea.getTextForRegion("highlightedRegion");

                if(j > 1) {
                    str = str.concat(highlightedText);
                } else {
                    str = highlightedText;
                }
            }
            highlightedTexts.add(str);
        }
    }
    document.close();

    return highlightedTexts;
}