Editing PDF documents with Cabaret Stage

Enter Stage Left!

By Hagen Höpfner

James Thew, Fotolia

In the past, Linux users had to rely on Wine and the Adobe Acrobat program to edit PDF documents or complete PDF forms on Linux. Switzerland's Cabaret Solutions AG now offers a product - called Cabaret Stage [1] - that is designed to fill the gap, at least on x86 Linux distributions. Because the tool is implemented in Java, Linux support was not a big step. This said, the current version of Cabaret Stage is not only a prototype, but it is also a commercial product that is free of charge for private use.

Installation

To install Cabaret Stage, accept the vendor's conditions of use (EULA) [2] and download it from the homepage. Users are not forced to disclose any personal details on the download page.

After obtaining the archive file, create a directory by entering mkdir ~/cabaret, copy the archive to the directory you just created and unpack by typing tar xvzf cabaretstage*.tar.gz.

Enter cabaretstage.sh to launch the program.You will need to have a Java runtime environment (Sun JRE 5) in order to do so.

System Requirements

Make sure you fulfill the system requirements that are specified in the product details on the website [3].

If you try to run Cabaret Stage on GCJ Java (which is installed by default on Ubuntu 6.10 and Suse 10.2), you will not even be able to open PDF documents, and the program will occasionally fail to launch. See Figure 1.

Figure 1: Cabaret Stage really requires Sun Java.

To resolve this issue on Ubuntu, enter the following command:

sudo apt-get installsun-java5-jre

Suse users can launch YaST, and install the java-1_5_0-sun package.

After installing the right Java environment, Cabaret Stage will launch more quickly, and it will now open PDF documents. If you only see a white page instead of the document content, check out the product details page to determine the cause.

According to the product details page, Cabaret Stage uses the SWT library by Eclipse.org [4], which in turn relies on the Cairo library.

Cairo 1.2, which more recent distributions such as Ubuntu 6.10 and Suse 10.2 include, has a known bug. To work around the program, you can download the following patch file from the Cabaret website [1]:

org.eclipse.swt.gtk.linux.x86_3.2.1.v3235-patched.jar

Use the file to replace the existing fiile:

org.eclipse.swt.gtk.linux.x86_3.2.1.v3235.jar

This change occurs in the ~/cabaret/lib directory.

Getting Started

Cabaret Stage is a classical, window-based application, with a menu at the top of the window and an icon bar below it for faster access to frequently used functions (Figure 1).

Hovering the mouse over an icon pops up a tooltip. The developers are aware of the fact that some icons do not scale properly, and work is in progress to remove the bug.

When you first launch the application, the left part of the window is occupied by a bookmark bar.

You can select View | Sidebar to enable more sidebars if needed (they can dock on the right, if you prefer). The document itself takes up the lion's share of the window.

If you open multiple documents at the same time, Cabaret Stage organizes them in tabs.

The download contains a PDF test document. You can select File | Open or press [Ctrl]+[O] to open the bank transfer form.

Clicking a line in the virtual form lets you edit the line. Pressing [Enter] confirms the changes, which Cabaret Stage then enters in the form.

Signature Methods

Of course, your bank would require you to sign a form before it can be processed. Cabaret Stage can help you do so, assuming you have a digital signature. See Figure 2.

Figure 2: Cabaret lets you select a preferred signature method.

Clicking the signature area in the form pops up a dialog in which you can select your preferred signature method.

As of this writing, there are no defined signature methods, and the dialog just displays an empty list.

Instrumentalization

Cabaret Stage sees itself as a stage on which multiple instruments can play. In line with this, plugins for added functionality are referred to as instruments in Cabaret-speak. Six instruments are available for Linux right now.

You can download instruments from the Cabaret website [2]:

• composeIT lets users create PDF documents with editable fields. Form design is dialog-based.

• drawIT lets users create simple drawings directly in PDF documents. It supports freehand drawing, ellipses, squares, as well as open and closed polygon elements.

• exchangeIT provides an interface to the outside world. It supports importing and exporting of form data from and to FDF and XFDF.

• inspectIT lets users inspect the PDF format and adjust its structure.

• portraIT is the import and export interface for the image formats JPEG, PNG, and TIFF.

• signIT lets users sign PDF documents electronically, supports simple digital signatures, manual signing via a pen pad or tablet PC, and signature cards.

After downloading them, simply unpack any new instruments in the Cabaret directory to install.

After relaunching the program, the extended functions, along with the matching icon bars and menu items, should become available. For an overview of the instruments you have installed, select Help | About and press the Instruments... button.

Since Cabaret Stage is a commercial product, additional instruments are subject to license. See Figure 3. For more information on licensing, refer to the Cabaret homepage [1].

Figure 3: Cabaret Stage highlights unlicensed instruments in blue in the overview.

To access the license management function, select Tools | License management.... You can test instruments without obtaining a license; however, Cabaret Stage prints a watermark of the company URL inside the document.

Cabaret Stage writes any changes you make to the document (including the watermark) to the PDF file when you save the document ([Ctrl]+[S]), making the changes visible to other PDF viewers. This process gives users a workaround for printing out modified documents. The prototype version of Cabaret Stage does not have a print function yet.

If you open the modified document in Acrobat Reader, you will be able to output the document in the normal way.

Conclusions

Cabaret Stage finally gives Linux users the ability to edit PDF documents. Note that the current version is a prototype and not suitable for production use.

The developers are aware of several restrictions and bugs and are working on resolving them. The initial release, which is planned for March 2007, will take the form of RPM and DEB packages. The release will include a print function and will be far faster than the prototype. Scrolling through documents in the trial version is rather slow.

Despite its current developer status - or maybe because of it - we recommend that you give Cabaret Stage a try and notify the developers of any issues you discover. The Cabaret website [5] has a form for reporting bugs.