Hi there, it's great to connect with you, I have read your requirements and I feel that I can be the best person to do this job, I have recently done a similar project where a user can resize the selection area from all 4 corners and whatever they finalise will be cropped and squared to png. Your requirement is very similar it's just that you need final output in pdf format. Let's talk more in chat if you need any clarification. Also, want to point out that I work at InMobi which is ad network so I know everything in and out about ad networks, and I can help you maximise your revenue.