Where does Android store the snapshots used on the recent apps?

Question

iOS takes a screenshot of an app every time it is sent to the background (maybe to show as a thumbnail when viewing recent apps. Details are available on this Stack Overflow question).

I did a little research and came to understand that the same feature is used by Android also. This Stack Overflow question deals with it.

This is a security issue if these snapshots are being stored somewhere in the device and are accessible to other apps.

I wanted to test this feature for my app, but I have no idea where Android stores these snapshots. I did some Googling but found nothing about the storage location.

Where are these snapshots located? Is this accessible to users other than root?

Answer 1

If what are you asking for is the location of the thumbnails displayed by Android when switching apps, then (on my LineageOS 13) they are stored inside /data/system/recent_images as PNG files called x_task_thumbnail.png (x being a possibly random number).

Since the thumbnails are owned by user system and group system, and their octal permissions are 600, you do need root to access them in whatsoever way.

Answer 2

As a follow-up to Death Mask Salesman's answer, Irfan Latif's comment, and also based on a self-experiment on Nexus 5 running Lineage OS 14.1 (Android 7.1) and self-research,

The directory is <SYSTEM_DIR><IMAGES_DIRNAME> where

• SYSTEM_DIR:

  • Default: /data/system/
  • On device that supports file-based encryption (FBE): /data/system_ce/<USER_ID>/

• IMAGES_DIRNAME: common values are recent_images and snapshots, but might be customized by vendors/ROM makers.

The snapshots filename format is <TASK_ID><TASK_THUMBNAIL_SUFFIX><IMAGE_EXTENSION> where:

• TASK_ID: task ID (arbitrary increasing number).
• TASK_THUMBNAIL_SUFFIX: default is _task_thumbnail
• IMAGE_EXTENSION: default is .png

Accessing these directories and their images needs root access.

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Sources:

• XDA Developers Forum
• Related commits on Android Source Code: 1, 2