Deploy device wallpapers with MANAGED INFO

MANAGED INFO includes a built-in wallpaper manager that applies a home and lock screen wallpaper based on the Custom device wallpaper (kiosk_custom_device_wallpaper) managed configuration key.

While this feature should work on custom DPC, the below guide focuses on AMAPI.

Your AMAPI policy should:

1. Install MANAGED INFO itself on the device.
2. Avoid policy‑level restrictions that block wallpaper modification.
3. Include the wallpaper configuration in managedConfiguration directly in the policy.

A minimal example policy with a managed configuration placeholder:

{
  "applications": [
    {
      "packageName": "org.bayton.managedinfo",
      "installType": "REQUIRED_FOR_SETUP",
      "defaultPermissionPolicy": "GRANT",
      "signingKeyCerts": [
        { "signingKeyCertFingerprintSha256": "<base64-encoded SHA-256>" }
      ],
      "managedConfiguration": {
        "kiosk_settings": {
          "kiosk_custom_device_wallpaper": "https://example.org/wallpapers/office.jpg"
        }      
      }
    }
  ]
}

EMMs that support native managed configuration input via a form (most do) should configure wallpapers through the GUI rather than embedding JSON in policy.

Wallpaper key

MANAGED INFO currently supports a single managed configuration key for wallpaper management:

• kiosk_custom_device_wallpaper - a direct HTTPS URL to an image file

Supported formats:

• PNG
• JPEG
• WebP

The wallpaper is always applied to both home and lock screens. Base64, HEIC/HEIF, and resource-based wallpapers are not currently supported.

Caching

MANAGED INFO stores:

• the downloaded file
• the last applied URL

This ensures wallpapers are only downloaded or applied when something changes.

When a wallpaper URL is present:

1. Validates the URL is non-empty.
2. Downloads the image.
3. Verifies the bitmap can be converted.
4. Compares against the previously applied URL.
   • If unchanged > no action taken.
   • If changed > applies wallpaper to home and lock screens.
5. Updates internal state to avoid repeated applications.

If kiosk_custom_device_wallpaper is removed or set to an empty string:

• MANAGED INFO will stop applying wallpapers. The OEM wallpaper will return.
• If the restriction key is explicitly present and empty, MANAGED INFO will also clear the currently applied wallpaper (where permitted by Android).
• If the key is absent, MANAGED INFO will not clear (to avoid accidental resets during boot or unhydrated configuration states).

Wallpaper does not apply

Check:

• the URL is reachable
• the file is a valid image format
• the device is not blocked by OEM wallpaper restrictions
• Ensure the managed configuration has hydrated (there may be a delay after boot).
• If the wallpaper resets, confirm the EMM is sending kiosk_custom_device_wallpaper consistently (missing keys are treated as “no-change”, not “clear”).

Slow or large downloads

Consider:

• using WebP for smaller file sizes
• hosting wallpapers on a CDN
• lowering resolution for budget devices

Wallpaper is cropped

All wallpapers provided are cropped and centred in line with the existing background image support within MANAGED INFO.

To guarantee what you want to show on the device is correctly aligned, please ensure the image contains all visual elements within the resolution of the device it's being set against. It's recommended, though understandably impractical, to create a wallpaper per-resolution and deploy across multiple policies. A future enhancement to this functionality may include the option for multiple image sizes, and MANAGED INFO will choose the most-suited for the device when setting the wallpaper.