I will do 4k wallpaper app and live wallpaper changer

Wallpapers app contains QHD premium quality AMOLED wallpapers and dark material backgrounds for your smartphone or tablet.

Auto Wallpaper Changer - Live Wallpapers:
- This Feature change Background automatically. User can choose time frequency to change wallpapers automatically. also user can choose rotation, scrolling, scaling, lossless trimming, transition and double-tap to change wallpaper
- if double-tap is enable user can double tap on visible are wallpaper change instantly

Saved Wallpaper:
- User can save wallpaper in your device and set that wallpaper as a auto wallpaper changer in device lock screen and home screen

Set As Wallpaper:
- User can set directly in your device home screen
- select option to choose where to change wallpapers

Save your battery:
Most of wallpapers apps will use smartphone battery energy excessively, but black wallpapers save your battery energy because they dont contain many colors.

Save your storage:
All of the dark amoled wallpapers are saved in cloud and NOT ON DEVICE and they will not be saved on your device if you dont download them, so you dont need to worry about your device storage.