org.apache.pdfbox.multipdf

Class LayerUtility

java.lang.Object

org.apache.pdfbox.multipdf.LayerUtility

public class LayerUtility
extends Object

This class allows to import pages as Form XObjects into a document and use them to create layers (optional content groups). It should used only on loaded documents, not on generated documents because these can contain unfinished parts, e.g. font subsetting information.

Constructor Summary

Constructors

Constructor and Description
LayerUtility(PDDocument document) Creates a new instance.

Method Summary

Modifier and Type	Method and Description
PDOptionalContentGroup	appendFormAsLayer(PDPage targetPage, PDFormXObject form, AffineTransform transform, String layerName) Places the given form over the existing content of the indicated page (like an overlay).
PDDocument	getDocument() Returns the PDF document we work on.
PDFormXObject	importPageAsForm(PDDocument sourceDoc, int pageNumber) Imports a page from some PDF file as a Form XObject so it can be placed on another page in the target document.
PDFormXObject	importPageAsForm(PDDocument sourceDoc, PDPage page) Imports a page from some PDF file as a Form XObject so it can be placed on another page in the target document.
void	wrapInSaveRestore(PDPage page) Some applications may not wrap their page content in a save/restore (q/Q) pair which can lead to problems with coordinate system transformations when content is appended.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LayerUtility

public LayerUtility(PDDocument document)

Creates a new instance.

Parameters:

document - the PDF document to modify

Method Detail

getDocument

public PDDocument getDocument()

Returns the PDF document we work on.

Returns:

the PDF document

wrapInSaveRestore

public void wrapInSaveRestore(PDPage page)
                       throws IOException

Some applications may not wrap their page content in a save/restore (q/Q) pair which can lead to problems with coordinate system transformations when content is appended. This method lets you add a q/Q pair around the existing page's content.

Parameters:

page - the page

Throws:

IOException - if an I/O error occurs

importPageAsForm

public PDFormXObject importPageAsForm(PDDocument sourceDoc,
                                      int pageNumber)
                               throws IOException

Imports a page from some PDF file as a Form XObject so it can be placed on another page in the target document.

You may want to call wrapInSaveRestore(PDPage) before invoking the Form XObject to make sure that the graphics state is reset.

Parameters:

sourceDoc - the source PDF document that contains the page to be copied

pageNumber - the page number of the page to be copied

Returns:

a Form XObject containing the original page's content

Throws:

IOException - if an I/O error occurs

importPageAsForm

public PDFormXObject importPageAsForm(PDDocument sourceDoc,
                                      PDPage page)
                               throws IOException

Imports a page from some PDF file as a Form XObject so it can be placed on another page in the target document.

You may want to call wrapInSaveRestore(PDPage) before invoking the Form XObject to make sure that the graphics state is reset.

Parameters:

sourceDoc - the source PDF document that contains the page to be copied

page - the page in the source PDF document to be copied

Returns:

a Form XObject containing the original page's content

Throws:

IOException - if an I/O error occurs

appendFormAsLayer

public PDOptionalContentGroup appendFormAsLayer(PDPage targetPage,
                                                PDFormXObject form,
                                                AffineTransform transform,
                                                String layerName)
                                         throws IOException

Places the given form over the existing content of the indicated page (like an overlay). The form is enveloped in a marked content section to indicate that it's part of an optional content group (OCG), here used as a layer. This optional group is returned and can be enabled and disabled through methods on PDOptionalContentProperties.

You may want to call wrapInSaveRestore(PDPage) before calling this method to make sure that the graphics state is reset.

Parameters:

targetPage - the target page

form - the form to place

transform - the transformation matrix that controls the placement of your form. You'll need this if your page has a crop box different than the media box, or if these have negative coordinates, or if you want to scale or adjust your form.

layerName - the name for the layer/OCG to produce

Returns:

the optional content group that was generated for the form usage

Throws:

IOException - if an I/O error occurs