How to display the full screen?

Settings -functions- full screen

How to customize keys?

Settings function customization key

How to screenshot ?

U8000: scan + power button
U9000 / u9300 / T80: "volume -" + power key

How to scan barcodes in the app?

(1) turn on the device
(2) click the demo application to enter its page
(3) press the button "scan"