Fix: Implements go back twice to exit in the whiteboard for gesture navigation

[ShaanNarendran]

Note

Tested out Opus 4.6 with code generation, still wrote all the code manually and tested everything physically

Purpose / Description

Currently, the double tap/swipe to back option doesn't work properly in the whiteboard and a single gesture/back press exits. This was a pain point for users who were using the whiteboard for language like Japanese.
Currently, this doesn't detect gestures since it involved an external API and I wasn't very sure of how that worked so didn't want to include it here.

Fixes

• Fixes "Press back twice" doesn't work on new study screen #20322

Approach

Implements a new doubleBackPressCallback function which intercepts back presses when the whiteboard is enabled. If the user presses back once, a snackbar is shown. If they press back again within 2 seconds, the activity finishes. If they don't, shouldReEnable checks whether the whiteboard is still active.

How Has This Been Tested?

Screen_recording_20260420_121417.webm

Checklist

Please, go through these checks before submitting the PR.

• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
• UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
• UI Changes: You have tested your change using the Google Accessibility Scanner

[david-allison]

I don't feel this handles Brayan's comment:

If we can also check whether the system is using gestures instead of buttons for navigation, it would be even better.

I skimmed the discussion, as far as I understand it, requiring a confirmation should only occur if the Android back gesture is enabled, rather than buttons.

---

In addition, implementer's choice

Consider a commit to change the string:

- Press back again to exit
+ Go back again to exit

[ShaanNarendran]

I don't feel this handles Brayan's comment:

If we can also check whether the system is using gestures instead of buttons for navigation, it would be even better.

I skimmed the discussion, as far as I understand it, requiring a confirmation should only occur if the Android back gesture is enabled, rather than buttons.

I had wanted to do this initially (https://stackoverflow.com/questions/74848618/how-to-detect-whether-gesture-navigation-or-button-navigation-is-active). But I was wondering why we wouldn't want to have the same thing for both navigation modes? I can make the change to using insets to detect gestures though, should just involve an extra function to detect gestures and then pass that to the ReEnable.
Edit: Since, Brayan designed reviewer I think it's best I follow his comments with the same, I'll push out a commit soon with both fixes ^^
Will change the string since then it would be nav agnostic, thanks for the find there!

[ShaanNarendran]

For future reference, using insets to detect navigation isn't reliable so using settings.secure is better
see: https://www.b4x.com/android/forum/threads/solved-how-to-determine-users-system-navigation-mode-back-button-or-side-swipe.159347/

[david-allison]

squash commits 1 and 2

[david-allison]

Almost!

[ShaanNarendran]

hopefully I implemented the compat part correctly, please let me know if there's any issues

edit: failing tests will figure it out shortly

[david-allison]

Almost!!

[BrayanDSO]

Looks great to me. Thanks

[david-allison]

It would be better to have the default as a Boolean

[ShaanNarendran]

flaky test I'm pretty sure

[david-allison]

Index: compat/src/main/java/com/ichi2/anki/compat/BaseCompat.kt
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/compat/src/main/java/com/ichi2/anki/compat/BaseCompat.kt b/compat/src/main/java/com/ichi2/anki/compat/BaseCompat.kt
--- a/compat/src/main/java/com/ichi2/anki/compat/BaseCompat.kt	(revision e911b16a595b247cf9f7842df36658270c0ae0db)
+++ b/compat/src/main/java/com/ichi2/anki/compat/BaseCompat.kt	(date 1776886772578)
@@ -289,8 +289,7 @@
     // Until API 29, gesture navigation does not exist
     override fun isUsingSystemGestureNavigation(
         context: Context,
-        default: Boolean,
-        gestureMode: Int,
+        defaultValue: Boolean,
     ): Boolean = false
 }
 
Index: compat/src/main/java/com/ichi2/anki/compat/CompatV29.kt
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/compat/src/main/java/com/ichi2/anki/compat/CompatV29.kt b/compat/src/main/java/com/ichi2/anki/compat/CompatV29.kt
--- a/compat/src/main/java/com/ichi2/anki/compat/CompatV29.kt	(revision e911b16a595b247cf9f7842df36658270c0ae0db)
+++ b/compat/src/main/java/com/ichi2/anki/compat/CompatV29.kt	(date 1776886686118)
@@ -87,11 +87,10 @@
 
     override fun isUsingSystemGestureNavigation(
         context: Context,
-        default: Boolean,
-        gestureMode: Int,
+        defaultValue: Boolean,
     ): Boolean {
-        val defaultMode = if (default) gestureMode else 0
-        return Settings.Secure.getInt(context.contentResolver, "navigation_mode", defaultMode) == gestureMode
+        val defaultMode = if (defaultValue) 2 else 0
+        return Settings.Secure.getInt(context.contentResolver, "navigation_mode", defaultMode) == 2
     }
 
     companion object {
Index: compat/src/main/java/com/ichi2/anki/compat/Compat.kt
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/compat/src/main/java/com/ichi2/anki/compat/Compat.kt b/compat/src/main/java/com/ichi2/anki/compat/Compat.kt
--- a/compat/src/main/java/com/ichi2/anki/compat/Compat.kt	(revision e911b16a595b247cf9f7842df36658270c0ae0db)
+++ b/compat/src/main/java/com/ichi2/anki/compat/Compat.kt	(date 1776886772584)
@@ -282,12 +282,10 @@
      * Note: this reads a `Settings.Secure` key that is not part of the public API.
      * It will not throw, but the result is manufacturer dependent.
      *
-     * @param default value returned when the `navigation_mode` key is unset
-     * @param gestureMode the value of `navigation_mode` representing gesture navigation
+     * @param defaultValue value returned when the `navigation_mode` key is unset
      */
     fun isUsingSystemGestureNavigation(
         context: Context,
-        default: Boolean = false,
-        gestureMode: Int = 2,
+        defaultValue: Boolean = false,
     ): Boolean
 }

Does this work (untested)

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