I had a similar problem and am using the following solution with AliVePdf. For calculating from pixel to mm I use the factor 0.353. This factor is the result, when you devide 297 / 842, where 297 is the length of an A4 Page and 842 is the same value in pixel. I think this is not a n exact method, because converting pixel to mm is also depending from the media. With displays normally you have 72dpi, for printouts more and even different resolutions. The size in pixel should be hold in a property, depending which type of object you are using.
> Am 28.02.2018 um 23:09 schrieb Scott <[hidden email]>:
> I am using the http://alivepdf to build pdf output from my flex app, I need to add an image directly after text, the problems is how do I work out the with in MM of the text
> Anyone got any ideas