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Source: Daniel Rubino/Windows Central

A few weeks ago, Google released Android 12L, formerly known as Android 12.1. According to Google, the operating system update will expire sometime in the first half of 2022. But the important thing is that this iteration of Android is the first to really focus on foldable devices and dual-screen devices.

Yes, I'm talking about dual screens. Although the detailed PR blog mentions foldable devices, many people try to decipher that Google means phones like the Samsung Galaxy Fold 3, not Microsoft's Surface Duo. After all, if Google intends to include dual screens, why not mention it?

Facts have proved that Google does. Let's solve this problem once and for all through the developer guide.

When taking screenshots on Surface Duo 2, Android fills in the gaps with software. Source: Windows Central

Before starting, I want to clarify some information about Surface Duo (currently on Android 10) and Surface Duo 2 (currently on Android 11). Both operating systems "see" these phones as single-screen devices. In fact, on Android 11, the operating system now draws a drain—the physical space between the two screens. You can see this in the screenshot where you get the entire canvas.

Much of the "magic" of Surface Duo and dual-screen apps is a combination of Microsoft Launcher, firmware, and more and more Android itself. Many things that Microsoft is doing on Surface Duo today are built into future iterations of Android. This is the big news.

As a side note, I believe this is one of the reasons why Microsoft has not invested heavily in customizing Android to maximize the effectiveness of Surface Duo today. Although the current user experience is lagging behind the vision, it is obvious from Android 12L that Google is integrating a large amount of such content into the operating system. If Microsoft invests resources in operating system customization, it will become redundant and useless within a year. Why invent the wheel when someone else is already doing this work for you?

An example of split screen and new taskbar for foldable devices in Android 12L. Source: Google

According to Google, Android 12L is "a special feature drop that makes Android 12 better on the big screen." More specifically, the operating system update optimizes the system UI for the new form factor and provides developers with new tools (API) to improve the application of the foldable display. This is the formalization of what Samsung, Microsoft, LG, Huawei and other companies have been forcing to happen in the past few years.

Google’s motivation for implementing these variants should be clear. Samsung has promoted this trend with its folding and flipping series of phones. Microsoft also has Surface Duo. But Google expects more devices to appear in 2022, and pointed out that this feature decline is "for the next wave of Android 12 tablets, Chromebooks and foldable devices."

There are even rumors that Google will also produce its own foldable phone next year, probably equipped with Android 12L.

Features such as a two-column notification bar with notifications and quick settings on the other side are an example of UI changes. The ability to cross applications and let applications move to the side of the display is another matter. The latter capability is what Microsoft does on the Surface Duo today, but it is not part of the Launcher and firmware, it can be built directly into the operating system. Google Play will also highlight apps optimized for these new forms.

You can read more about it from Google's 12L summary, but it becomes interesting in the developer documentation.

Are these two foldable? They are. Source: Daniel Rubino/Windows Central

But Google is only talking about foldable, right? That is the wrong question. What you should ask is: How does Google define foldable products? Because the company gave the definition.

Let's start with Google's Material Design 3-the next evolution of its UI is directly aimed at the "adaptive experience." On its page, Google described the term thoughtfully, and I think it’s vital to this conversation. Speaking of foldable, here is a direct definition, which clearly refers to the hinge:

There are two types of hinges on folding devices:

The second point is the most relevant and seems to end the discussion: foldable includes dual screens. But if you want more, Google continues:

In the unfolded position, the folding hinge of the device will be obvious on some models. In the unique case of Microsoft Surface Duo, the hinge physically separates the screen.

How does Google define a foldable screen. Source: Google

Therefore, when it comes to the new Material Design 3, Google called Surface Duo. Google then gave an example of how developers should design their UI around these limitations:

On devices with physical hinges, designing the screen as two different halves allows the composition to work well on the seams and on the screen... avoid placing key operations along the central hinge, such as dialog buttons.

The complete overview of Material Design 3 is very fascinating, so if you are interested in this topic, I encourage you to read it.

When it comes to Android application development and 12L, Google lists a lot in its Android Developer Guide. Here are some examples explaining foldable and dual screens:

Foldable devices can be folded in many ways, such as inward (folding the display into the device) or outward (the display surrounds the device). Some foldable devices have two screens; others, such as foldable flip phones, have only one.

Foldable devices have a foldable part in the display that separates the two parts (usually half) of the display. The fold has a size and you can use the occlusionType to separate the two parts, which defines whether the fold occludes part of the display (dual-screen devices report complete occlusion).

This occlusionType is essential because it helps define software gaps for dual-screen devices such as Surface Duo. It is again referenced under "Making your application foldable", where the documentation provides more information about what "foldable" means:

FoldingFeature is a DisplayFeature that provides information related to the hinge between two physical display panels of a folding or dual-screen device with a foldable display.

FoldingFeature also includes information such as occlusionType (indicating whether the fold or hinge is partially hidden) and isSeparating (indicating whether the folding function creates two logical screen areas). This information can be used to determine the position on the screen element to support dual-screen devices and avoid positioning active elements (such as buttons) on hidden folding functions.

More references about Surface Duo can be found under Jetpack WindowManger, especially in the codelab section, which provides tutorials for building such applications:

This practical Codelab will teach you the basics of developing dual-screen and foldable devices. Once completed, you will be able to enhance the application to support devices such as Microsoft Surface Duo and Samsung Galaxy Z Fold3.

It is obvious from Google's definition and examples in the official Android documentation that dual-screen devices are a subset of foldable devices. Android 12L can go a long way in formalizing this distinction in operating systems, applications, and UI.

Microsoft also has a blog that summarizes the new features of Android 12L and how it connects with their own work to help developers. It is worth reading.

Source: Daniel Rubino/Windows Central

I hope this walkthrough fully proves that Android 12L and future versions of Android hardware definitely include dual-screen devices under foldable devices. Once I read the supporting documentation (not just the PR blog summary), I don't think it is controversial.

Of course, this does not mean that Surface Duo has suddenly become a slam dunk. Microsoft needs to solve the touch sensitivity problem as soon as possible, which has nothing to do with Android 12L. Other "quirks" of the camera application, updating your own application, and improving the ink experience also need to be fixed. Concerns about pricing, or even just convincing people to want this device, are other major obstacles.

But Android 12L is also very important. When it comes out, the Surface Duo experiment will be close to its third year. This means that the operating system may eventually catch up with Microsoft in terms of hardware, especially in terms of overall operating system design, features, and application compatibility. Android 12L has also begun to become the mainstream of these new folding phones and devices, bringing the much-needed halo effect to Surface Duo.

The $64,000 question is whether Microsoft can deliver Android 12L in time? My intuition is that the company may skip Android 12.0 and launch 12L (as it should), but it needs to do so as soon as possible to avoid the fiasco of replicating Android 11 with the original Surface Duo.

We will see what will happen in the next few months, because everyone is paying attention to Android 12L.

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Daniel Rubino is the executive editor of Windows Central. Since the site was called WMExperts (and later Windows Phone Central) in 2007, he has been covering Microsoft here. His interests include Windows, Surface, laptops and modern computing. Follow him on Twitter: @daniel_rubino.