Android Galaxy S4 — Activity that is visible over lock screen

Question

A few years ago, I wrote an alarm app that worked on Android 2, and I\'m now trying to upgrade it to work on Android 4. Specifically, on the Samsung Galaxy S4.

On A

Answer 1

Right - So I have been struggling with this one recently but with a 5.0.2 Galaxy Tab A. Unsurprisingly what works on every other device does not work on Samsung (this has been the case since the first Samsung Galaxy device, they break something new each release!)

The general solution for showing an Activity over the lock screen for most devices is

//wake up device and show even when on lock screen
getWindow().addFlags(WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD |
        WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED |
        WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON |
        WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON |
        WindowManager.LayoutParams.FLAG_FULLSCREEN);

However this does not work for samsung devices. Removing FLAG_DISMISS_KEYGUARD however does this trick.

Looking at the docs for this flag we have

Window flag: when set the window will cause the keyguard to be dismissed, only if it is not a secure lock keyguard. Because such a keyguard is not needed for security, it will never re-appear if the user navigates to another window (in contrast to FLAG_SHOW_WHEN_LOCKED, which will only temporarily hide both secure and non-secure keyguards but ensure they reappear when the user moves to another UI that doesn't hide them). If the keyguard is currently active and is secure (requires an unlock pattern) than the user will still need to confirm it before seeing this window, unless FLAG_SHOW_WHEN_LOCKED has also been set.

and for FLAG_SHOW_WHEN_LOCKED we have

Window flag: special flag to let windows be shown when the screen is locked. This will let application windows take precedence over key guard or any other lock screens. Can be used with FLAG_KEEP_SCREEN_ON to turn screen on and display windows directly before showing the key guard window. Can be used with FLAG_DISMISS_KEYGUARD to automatically fully dismisss non-secure keyguards. This flag only applies to the top-most full-screen window.

You can see they can be used together but it seems samsung will not bother with FLAG_SHOW_WHEN_LOCKED if the device is locked and FLAG_DISMISS_KEYGUARD is present. My app requires a lock screen to be setup so removing the dismiss keyguard flag actually allows me to show full screen Activities over the lock screen. Yay for me, nay for samsung.