you have to thin out your points... one way would be to filter data in touch_moved to only register motions larger than X pixels, or that occur after a long delay. then you would use a bezier arc to connect.
you have to compute the control points yourself, which may be non trivial.
There are many other ways to send data to your pc, the one I particularly prefer is uploading the data to a drive and downloading it on the required device. You may also try FTP server. However, the easiest method would be to use different applications that send songs, images to devices using wifi like ShareIt. You could also use the inbuilt bluetooth in your devices, if it is available. Try transferring https://sc-downloader.net/ songs with above mentioned ways to know which one is best suited for your device.