I use Dio dictionary
, function gesture on screen get text to search
L
I think you want something like a handwriting recognition library. It seems you want to enable the users to write something on the screen ,when app is ON and then you can convert it to text and use it. There are many existing questions which might help you find a handwriting recognition library. See:
Handwriting recognition API's for android applications
https://stackoverflow.com/questions/768664/recommendations-for-handwriting-recognition-libraries-packages-in-java
You can also use Tesseract library to recognize handwriting. See:
Tesseract handwriting with dictionary training
I haven't used any so I am not sure which one is the best but I hope that these links help you.