iText create pushbutton at relative position

I'd like to create a pushbutton on a pdf using iText. However i cannot create it at any fixed/ position. It needs to be done at a relative position. Like say, 5-6 cm. 开发者_如何学编程before end of PDF. Any idea on how to do it?

Another way might be creating an invisible field in acrobat, getting its field position and then creating the button at that position. However i've been unable to retrieve field positions or even view them. Could someone help me with this?

Regards, Sameer

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you should always know the size of your pages, and if you know that you will be able to put it at a relative 5-6cm of the page. some info that might help you is that all the coor and stuff in itext is done in points and there are 72pts in an inch.