Tiling with iText, and adding margins

问题:

Im following the Tiling Hero example (http://itextpdf.com/examples/iia.php?id=116) but I'd like to be able to add margins to each page.

回答1:

Please take a look at the TileClipped example. It is based on the TilingHero example, but it has a twist:

public void manipulatePdf(String src, String dest)
    throws IOException, DocumentException {
    float margin = 30;
    // Creating a reader
    PdfReader reader = new PdfReader(src);
    Rectangle rect = reader.getPageSizeWithRotation(1);
    Rectangle pagesize = new Rectangle(rect.getWidth() + margin * 2, rect.getHeight() + margin * 2);
    // step 1
    Document document = new Document(pagesize);
    // step 2
    PdfWriter writer
        = PdfWriter.getInstance(document, new FileOutputStream(dest));
    // step 3
    document.open();
    // step 4
    PdfContentByte content = writer.getDirectContent();
    PdfImportedPage page = writer.getImportedPage(reader, 1);
    // adding the same page 16 times with a different offset
    float x, y;
    for (int i = 0; i < 16; i++) {
        x = -rect.getWidth() * (i % 4) + margin;
        y = rect.getHeight() * (i / 4 - 3) + margin;
        content.rectangle(margin, margin, rect.getWidth(), rect.getHeight());
        content.clip();
        content.newPath();
        content.addTemplate(page, 4, 0, 0, 4, x, y);
        document.newPage();
    }
    // step 4
    document.close();
    reader.close();
}

Do you see how we make a distinction between rect and pagesize? We define rect as the size of the original pages and we define pagesize as a size that is slightly bigger (depending on the value of margin).

We use rect when we define the offset x and y, but we add margin to slightly change that offset. We change the offset because we clip the pagesize. Clipping is done by defining a clipping path:

content.rectangle(margin, margin, rect.getWidth(), rect.getHeight());
content.clip();
content.newPath();

Everything added after these three lines will be clipped by the rectangle we define in the rectangle() method. You may want to add extra saveState()/restoreState() methods if you also want to add other content, especially if that content needs to be added outside the clipping path.