Fix immersive mode and virtual keyboard height issue on Android

[syntaxerror247]

Fixes #86663

This PR fixes the incorrect virtual keyboard height issue and adds support on API 29 and older.
Fixes all the known immersive and edge-to-edge mode issues.

[Calinou]

@kilojool Can you test this PR locally to see if it resolves the issue?

[syntaxerror247]

@llama-nl It might not work on embedded window. Can you test with exported project, or try disabling embedded window and with gamebar hidden.

[llama-nl]

@syntaxerror247 ok, it works in protrait mode. I think it doesn't working in landscape mode?

[syntaxerror247]

@syntaxerror247 ok, it works in protrait mode. I think it doesn't working in landscape mode?

That's an issue with the MRP project. Stretch mode is set to canvas_item, which scales the viewport (as seen in landscape). But the keyboard height is not scaled, it's in physical pixels.

To fix this, either set stretch mode to disabled, or divide the keyboard height by the scale

size.y = get_viewport_rect().size.y - (DisplayServer.virtual_keyboard_get_height() / get_viewport_transform().get_scale().y)

[kilojool]

It works great on Android 12 for me, but on Android 9 it always returns 0 regardless if the keyboard is visible or not.

[syntaxerror247]

It works great on Android 12 for me, but on Android 9 it always returns 0 regardless if the keyboard is visible or not.

@kilojool The method used to calculate the virtual keyboard height is only available on Android 11 and above. I’ve now added support for older versions as well. Could you please test it again and let me know if it works now?

[kilojool]

@syntaxerror247 Yes, that fixed it for me on Android 9 also! Nice work! =D

[Alex2782]

Test project: NavigationBarProblem.zip

Tested on Samsung Tab S7 (Android 13) and LG Nexus 5X (Android 8)

I had to modify MRP, disable Gradle build (Godot 4.3 custom mods, probably no longer compatible), and take scaling into account.

func _process(_delta):
	#https://github.com/godotengine/godot/issues/86663#issuecomment-2132230189
	var keyboard_height := DisplayServer.virtual_keyboard_get_height()
	self.size.y = get_viewport_rect().size.y - (keyboard_height / get_viewport_transform().get_scale().y)

---

On the LG Nexus 5X (Android 8), there are problems when Immersive mode is enabled. As soon as the keyboard appears, Immersive mode is exited. Probably OS specific. On Samsung Tab S7 (Android 13), I couldn't find any issues.

Video: Issues / Test LG Nexus 5X, Immersive mode + Edge To Edge

nexus_5x.mp4

Input field is suddenly behind the navigation bar when the keyboard is hidden again.

[syntaxerror247]

On the LG Nexus 5X (Android 8), there are problems when Immersive mode is enabled. As soon as the keyboard appears, Immersive mode is exited. Probably OS specific. On Samsung Tab S7 (Android 13), I couldn't find any issues.

Video: Issues / Test LG Nexus 5X, Immersive mode + Edge To Edge
Input field is suddenly behind the navigation bar when the keyboard is hidden again.

I also noticed issues with immersive/edge-to-edge mode on android 9 (emulator), I'm looking into it.

[Alex2782]

It works better than before on Nexus 5X Android 8, in Immersive Mode.

However, if Immersive Mode is disabled and Edge to Edge is enabled, the input field behind the navigation bar disappears. Partially on the Samsung Tab S7, and completely on the Nexus 5X.

Screenshots

Samsung Tab S7 (Android 13)

---

Google Nexus 5X (Android 8)

[Alex2782]

Test project: NavigationBarProblem.zip

DisplayServer.virtual_keyboard_get_height()

Now the function returns 0 (Android 8) if Immersive Mode is disabled.
Only the first time the keyboard is displayed height = 0, the second time it works.

[Alex2782]

See above.

Can you reproduce it? Otherwise, I'll check it more closely on my device later.

[syntaxerror247]

However, if Immersive Mode is disabled and Edge to Edge is enabled, the input field behind the navigation bar disappears. Partially on the Samsung Tab S7, and completely on the Nexus 5X.

That's an exected behaviour. App shouldn't place any interactable node at bottom, if using use edge-to-edge mode.

[syntaxerror247]

DisplayServer.virtual_keyboard_get_height()

Now the function returns 0 (Android 8) if Immersive Mode is disabled.
Only the first time the keyboard is displayed height = 0, the second time it works.

Yes, I can reproduce this on an Android 7 emulator (not reproducible on Android 9; I haven't tested on 8).
The WindowInsetsAnimationCallback doesn’t get triggered the first time the keyboard opens. I looked into it but couldn’t find anything. Initially, I suspected it might be an emulator bug, but since it can be reproduced on a physical device as well, it's likely a bug in the API itself.

We have two possible solutions:

1. Revert to my previous approach using OnGlobalLayoutListener for Android 7 and 8.

2. Document this behavior: the keyboard height is not returned the first time the keyboard opens for non-immersive mode on Android 7 and 8.