Using iTextPDF to crop page scrolling

Question

I have a pdf that contains some data, followed by some spaces. I don’t know how big the data is, but I would like to trim the data spaces

    PdfReader reader = new PdfReader(PDFLOCATION);
    Rectangle rect = new Rectangle(700, 2000);
    Document document = new Document(rect);
    PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(SAVELCATION));

     document.open();

        int n = reader.getNumberOfPages();
        PdfImportedPage page;
        for (int i = 1; i <= n; i++) {
            document.newPage();
            page = writer.getImportedPage(reader, i);
            Image instance = Image.getInstance(page);
            document.add(instance);
        }
        document.close();

Is there a way to crop / crop spaces for each page in a new document? This PDF file contains vector graphics.

I use iTextPDF but can switch to any Java library (mavenized, preferred version of Apache)

Answer 1

Since the actual solution has not been published, here are some pointers from the accompanying itext-questions mailing list thread :

• , PdfWriter + getImportedPage, PdfStamper. PdfStamper :

  PdfReader reader = new PdfReader(resourceStream); 
  PdfStamper stamper = new PdfStamper(reader, new FileOutputStream("target/test-outputs/test-trimmed-stamper.pdf")); 
  
  // Go through all pages 
  int n = reader.getNumberOfPages(); 
  for (int i = 1; i <= n; i++) 
  { 
      Rectangle pageSize = reader.getPageSize(i); 
      Rectangle rect = getOutputPageSize(pageSize, reader, i); 
  
      PdfDictionary page = reader.getPageN(i); 
      page.put(PdfName.CROPBOX, new PdfArray(new float[]{rect.getLeft(), rect.getBottom(), rect.getRight(), rect.getTop()})); 
      stamper.markUsed(page); 
  } 
  stamper.close(); 
  

  , getOutputPageSize. . .

• , iText. TextMarginFinder. getOutputPageSize ( ) :

  private Rectangle getOutputPageSize(Rectangle pageSize, PdfReader reader, int page) throws IOException 
  { 
      PdfReaderContentParser parser = new PdfReaderContentParser(reader);
      TextMarginFinder finder = parser.processContent(page, new TextMarginFinder());
      Rectangle result = new Rectangle(finder.getLlx(), finder.getLly(), finder.getUrx(), finder.getUry());
      System.out.printf("Text/bitmap boundary: %f,%f to %f, %f\n", finder.getLlx(), finder.getLly(), finder.getUrx(), finder.getUry());
      return result;
  }
  

  test.pdf :

  

  , ( ) .

• , , , , (TextMarginFinder ) . , PDF.

• PDF , - , (, ) .

  . PDF , getOutputPageSize, :

  Rectangle result = new Rectangle(pageSize.getLeft(), finder.getLly(), pageSize.getRight(), finder.getUry());
  

  :

  

  .

  . - (, , ), TextMarginFinder, .

---

( 2015 ., iText 5.5.6-SNAPSHOT)

, 5.5.6-SNAPSHOT, , . TextMarginFinder iText, ExtRenderListener, :

@Override
public void modifyPath(PathConstructionRenderInfo renderInfo)
{
    List<Vector> points = new ArrayList<Vector>();
    if (renderInfo.getOperation() == PathConstructionRenderInfo.RECT)
    {
        float x = renderInfo.getSegmentData().get(0);
        float y = renderInfo.getSegmentData().get(1);
        float w = renderInfo.getSegmentData().get(2);
        float h = renderInfo.getSegmentData().get(3);
        points.add(new Vector(x, y, 1));
        points.add(new Vector(x+w, y, 1));
        points.add(new Vector(x, y+h, 1));
        points.add(new Vector(x+w, y+h, 1));
    }
    else if (renderInfo.getSegmentData() != null)
    {
        for (int i = 0; i < renderInfo.getSegmentData().size()-1; i+=2)
        {
            points.add(new Vector(renderInfo.getSegmentData().get(i), renderInfo.getSegmentData().get(i+1), 1));
        }
    }

    for (Vector point: points)
    {
        point = point.cross(renderInfo.getCtm());
        Rectangle2D.Float pointRectangle = new Rectangle2D.Float(point.get(Vector.I1), point.get(Vector.I2), 0, 0);
        if (currentPathRectangle == null)
            currentPathRectangle = pointRectangle;
        else
            currentPathRectangle.add(pointRectangle);
    }
}

@Override
public Path renderPath(PathPaintingRenderInfo renderInfo)
{
    if (renderInfo.getOperation() != PathPaintingRenderInfo.NO_OP)
    {
        if (textRectangle == null)
            textRectangle = currentPathRectangle;
        else
            textRectangle.add(currentPathRectangle);
    }
    currentPathRectangle = null;

    return null;
}

@Override
public void clipPath(int rule)
{
}

( : MarginFinder.java)

.

: . , , . , , . .

TestTrimPdfPage.java.