As Android P official launch nears, Google has released guidelines for developers updating their apps to support the notch, or as Google calls it, the "display cutout". Google has also released details of what developers can expect from OEMs manufacturing smartphones with display cutouts. This comes due to the new display notch trend that has hit the smartphone industry, ever since the launch of the iPhone X last year.
Apart from giving developers tips on "taking advantage of the cutout area" and testing their apps with the cutout, Google notes that it ensured that hardware partners will also follow certain rules for efficient app compatibility across all phones with display notches. This included some must-dos in display design and a cap of a maximum of two cut-outs per screen. Furthermore, Google allows notches only on the top or bottom of the display, and nowhere else. Here's a lowdown given by Google to all manufacturers.
First, devices must ensure that their cutouts do not negatively affect apps. There are two key requirements:
1) In portrait orientation, with no special flags set, the status bar must extend to at least the height of the cutout.
2) In fullscreen or landscape orientation, the entire cutout area must be letterboxed.
Second, devices may only have up to one cutout on each short edge of the device. This means that:
1) You won't see multiple cutouts on a single edge, or more than two cutouts on a device.
2) You won't see a cutout on the left or right long edge of the device.
Within these constraints, devices can place cutouts wherever they want.
This is done so that developers can make apps that work consistently across devices with one or two display cut-outs, as well as devices with 18:9 and larger aspect ratios.
For developers, Google notes that Android P brings platform support for display cutouts with APIs that can be used to show content inside or outside of the cutout. It has also detailed how developers can make their apps compatible with devices that support display notches.