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ZTE’s Axon M Creates Software for Folded Smartphones
April 09, 2018
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While the Axon M does not solve any of the foldable display issues, ZTE has tackled the classic dual-screen dilemma: Allowing apps to leverage the added real estate without compromising the user experience. The Axon M has four viewing modes, which are accessible with a tap of the special “M” key in the navigation bar: Traditional Mode (a single screen view), Extended Mode, Dual Mode, and Mirror Mode. Traditional Mode runs apps in portrait mode on the Axon M’s primary display, just like a regular smartphone. Extended Mode expands the Android interface the length of the two screens, doubling the horizontal resolution from 1080 pixels to 2160 pixels. Dual Mode is more or less akin to Android Nougat’s split-screen mode, running two apps side by side—one on each of the Axon M’s display panels. And Mirror Mode duplicates the Axon M’s primary screen on the secondary screen.
For the most part, the Axon M’s Android 7.1 Nougat-based firmware is fairly close to stock. That’s by design: the phone’s four screen modes tap into Android’s native display framework, obviating the need for developers to use a custom tool or software development kit to get apps up and running. Dual Mode takes advantage of Nougat’s Multi-Window feature—any app that supports split-screen on Nougat is fully compatible with the Axon M’s Dual Mode. It’s a boon for multitasking; the extra screen real estate afforded by Axon M’s second screen makes multi-window much more useful.  Extended Mode, meanwhile, treats the Axon M’s two screens like one giant, high-resolution screen, almost like a tablet. The implications aren’t to be understated—Android app developers create multiple app layouts and assets so that apps scale properly across smartphones and tablets with different resolutions, screen sizes, and screen densities. Dual-panel devices such as the Kyocera Echo required developers to use proprietary build systems and documentation in order to get them to work on secondary screens. But to optimize an app for the ZTE Axon M, all that’s required is adding a new layout.

Basically, optimizing an app for the Axon M is like optimizing an app for a tablet, albeit with an odd 2160×1920 resolution. When the Axon M is in Extended Mode, applications and games automatically switch to the appropriate layout, in some cases stretching to fill the phone’s two Full HD displays. Some apps, like YouTube, split interface elements down the middle: videos and playback controls occupy one panel, while descriptions, comments, and related are relegated to the other panel. (ZTE demoed a camera app at the Consumer Electronics Show that displayed the viewfinder on the Axon M’s primary screen and colorful imagery on the second screen, designed to catch the attention of a young child.) Apps without compatible layouts behave a little unpredictably, but that’s to be expected—just as applications without tablet layouts don’t display properly on larger devices, apps that haven’t been optimized for Extended Mode resolution are at the mercy of Android’s automatic scaling.
 
 
Figure 1: ZTE’s Axon M

Source: Company Data

Optimizing an app for the Axon M is like optimizing an app for a tablet, albeit with an odd 2160×1920 resolution. When the Axon M is in Extended Mode, applications and games automatically switch to the appropriate layout, in some cases stretching to fill the phone’s two Full HD displays. Some apps, like YouTube, split interface elements down the middle: videos and playback controls occupy one panel, while descriptions, comments, and related are relegated to the other panel. (ZTE demoed a camera app at the Consumer Electronics Show that displayed the viewfinder on the Axon M’s primary screen and colorful imagery on the second screen, designed to catch the attention of a young child.) Apps without compatible layouts behave a little unpredictably, but that’s to be expected—just as applications without tablet layouts don’t display properly on larger devices, apps that haven’t been optimized for Extended Mode resolution are at the mercy of Android’s automatic scaling.
 
The reason that foldable phones haven’t caught on is twofold: the hardware wasn’t fast enough to drive split-screen apps on high-resolution panels, and the software hadn’t caught up to support multiple displays. That’s finally changing.
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With the Axon M, ZTE has established an important precedent: Treating folding phones’ large-screen form factor as a single display in software.
Assuming a foldable phone of the future—that is to say, phones with seamless, flexible displays that unfurl into a tablet form factor—adopt the same software approach, it’ll be an cinch for app developers to support them. In Android Studio, optimizing an app for the ZTE Axon M is as easy as creating a Layout XML file for the phone’s Dual Mode density, sticking it in a new /res/layout directory, and specifying alternate drawable resources. It’s no different than supporting any other device with a unique screen size, display density, or resolution, and while that might sound like a no-brainer, the dual-screen phones of yesteryear weren’t nearly as easy to support.