Karaka’s signature can be displayed horizontally. After decompiling the apk, modify the AndroidManifest.xml and change the landscape horizontal screen to "portrait" vertical screen. If you want to rotate freely, just delete the corresponding horizontal screen. You must replace them all. When swiping the card, the device display will prompt please Customer signature keyword, just use a special pen to sign on the display screen. The advantage of electronic signature is that the electronic component invoice is stored to prevent the risk of order adjustment if the paper invoice is lost.