Complete editing of pdf documents is made possible with PDFedit. You can change either raw pdf objects (for advanced users) or use predefined gui functions. Functions can be easily added as everything is based on a scripts.
PDFEdit :
About the project
PDFedit is free and open source library for manipulating PDF documents, released under terms of GNU GPL version 2. It includes PDF manipulating library based on xpdf, GUI and set of command line tools.
Library
Multiplatform library working on Unix systems, Windows32/64 and also Windows CE and others. You can use it to read, change and extract information from a PDF file. It is based on xpdf library.
Tools
Tools include example usage of the library which proved to be useful.
GUI
Graphical interface based on QT3.x which heavily depends on scripting; therefore, any user can modify the behaviour by scripts and plugins. There is also a beta version of QT4.x based windows pdf editor.
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