itext spacingBefore property applied to Paragraph

问题:

I have an issue with the itext library that can be described as follow :

I want to put a vertical space between two paragraphs by using the spacingBefore property on the second paragraph.

The problem is that from a certain value of space units (by default point unit), itext causes the second paragraph to be displayed on a new page even though there is obviously enough space to put the 2 paragraphs on the same page.

This code illustrates this situation :

    public static void main(String[] args) throws Exception {
       Document document = new Document();
       OutputStream result = new FileOutputStream("output.pdf");
       PdfWriter.getInstance(document, result);
       document.open();

       Paragraph paragraph1 = new Paragraph("First paragraph");

       Paragraph paragraph2 = new Paragraph("Second paragraph");
       //380 causes the new page...
       paragraph2.setSpacingBefore(380f);

       //...whereas 370 does not
       //  paragraph2.setSpacingBefore(370f);

       document.add(paragraph1);
       document.add(paragraph2);

       document.close();
}

Does someone hava an explication of this strange behaviour?

Thanks in advance

回答1:

I have copied your code into a standalone example. You can find this example here: ParagraphSpacingBefore

public void createPdf(String filename) throws IOException, DocumentException {
    Document document = new Document();
    PdfWriter.getInstance(document, new FileOutputStream(filename));
    document.open();
    Paragraph paragraph1 = new Paragraph("First paragraph");
    Paragraph paragraph2 = new Paragraph("Second paragraph");
    paragraph2.setSpacingBefore(380f);
    document.add(paragraph1);
    document.add(paragraph2);
    document.close();
}

I don't think this is different from what you're doing, but in my case, the two paragraphs are on a single page. Please check paragraph_spacebefore.pdf to find out for yourself.

Maybe you are also applying a spacing before to paragraph1 or maybe you are using an old version of iText (e.g. 2.1.7, a version that is obsolete and should no longer be used) or maybe you are using an unofficial version of iText (e.g. iText 4, a version that is created by a third party and of which no one knows if it's even legal to use).

In short: the problem can't be explained because the problem can't be reproduced.

回答2:

As stated by Bruno, I was using an "old" buggy version of itext : 5.1.2 released in 2012. This bug was fixed by version 5.5.1 as mentionned in the changelog http://itextpdf.com/changelog/551 :

Bugfix regarding spacing before and after when a new page is created.

When using a newer version, everthing works just fine :)