After months of living with the developer preview, we’ve got a pretty good handle on what’s in Android 8.0 Oreo. Still, some surprises are lurking inside. For example, the use of so-called “Task Snapshots” in Android 8.0 means your overview thumbnails will look better, use less memory, and actually represent what you see upon returning to an app.
A Task Snapshot is an infrastructure feature of Android 8.0, so there’s no setting to mess with on your end. It’s essentially a combination of Recent Thumbnails and Saved Surfaces. When an app goes into the background,
the Window Manager places a screenshot of it directly into the graphics buffer. This is retained as long as the app remains in memory and is displayed when you see that app in the multitasking interface.
Since the screenshot lives in the graphics buffer, there’s no additional copying step required to display it in overview. That uses less memory, and thus the image can be higher quality. Previously, the thumbnail used in overview was downsampled by 64% to save memory.
The transition from the thumbnail to full app is much smoother as a result. Additionally, since the thumbnail matches the graphics buffer, what you see in the thumbnail will always be what you get when tapping on the app.
Developers don’t have to do anything to enable Task Snapshots in Android 8.0—it’s enabled for all activities by default.