This is the opensource version of pinholeCalculator avalable on playstore at https://play.google.com/store/apps/details?id=com.madam.PinHoleCalculator.
It was my first Android application so the code is a little dirty and some translation in English have to be done. This application will not replace the existing application on PlayStore(lost the Master Key...) but will be push on a new one, so it need to be renamed. Your proposition are welcome.
PS. I am french and my English is not perfect so don't hesitate to correct me.
best regards.
Mickaël