Enhancement - optional transparent homoglyph encoding of a few characters in certain languages for more compact and efficient text messages (#4491)

core/prefs/src/main/kotlin/org/meshtastic/core/prefs/di/PrefsModule.kt

@@ -30,6 +30,8 @@ import org.meshtastic.core.prefs.emoji.CustomEmojiPrefs
 import org.meshtastic.core.prefs.emoji.CustomEmojiPrefsImpl
 import org.meshtastic.core.prefs.filter.FilterPrefs
 import org.meshtastic.core.prefs.filter.FilterPrefsImpl
+import org.meshtastic.core.prefs.homoglyph.HomoglyphPrefs
+import org.meshtastic.core.prefs.homoglyph.HomoglyphPrefsImpl
 import org.meshtastic.core.prefs.map.MapConsentPrefs
 import org.meshtastic.core.prefs.map.MapConsentPrefsImpl
 import org.meshtastic.core.prefs.map.MapPrefs
@@ -54,6 +56,10 @@ import javax.inject.Singleton
 @Retention(AnnotationRetention.BINARY)
 internal annotation class AnalyticsSharedPreferences
 
+@Qualifier
+@Retention(AnnotationRetention.BINARY)
+internal annotation class HomoglyphEncodingSharedPreferences
+
 @Qualifier
 @Retention(AnnotationRetention.BINARY)
 internal annotation class AppSharedPreferences
@@ -101,6 +107,8 @@ interface PrefsModule {
 
     @Binds fun bindAnalyticsPrefs(analyticsPrefsImpl: AnalyticsPrefsImpl): AnalyticsPrefs
 
+    @Binds fun bindHomoglyphEncodingPrefs(homoglyphEncodingPrefsImpl: HomoglyphPrefsImpl): HomoglyphPrefs
+
     @Binds fun bindCustomEmojiPrefs(customEmojiPrefsImpl: CustomEmojiPrefsImpl): CustomEmojiPrefs
 
     @Binds fun bindMapConsentPrefs(mapConsentPrefsImpl: MapConsentPrefsImpl): MapConsentPrefs
@@ -127,6 +135,12 @@ interface PrefsModule {
         fun provideAnalyticsSharedPreferences(@ApplicationContext context: Context): SharedPreferences =
             context.getSharedPreferences("analytics-prefs", Context.MODE_PRIVATE)
 
+        @Provides
+        @Singleton
+        @HomoglyphEncodingSharedPreferences
+        fun provideHomoglyphEncodingSharedPreferences(@ApplicationContext context: Context): SharedPreferences =
+            context.getSharedPreferences("homoglyph-encoding-prefs", Context.MODE_PRIVATE)
+
         @Provides
         @Singleton
         @AppSharedPreferences

core/prefs/src/main/kotlin/org/meshtastic/core/prefs/homoglyph/HomoglyphPrefs.kt

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2026 Meshtastic LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.meshtastic.core.prefs.homoglyph
+
+import android.content.SharedPreferences
+import kotlinx.coroutines.channels.awaitClose
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.callbackFlow
+import org.meshtastic.core.prefs.PrefDelegate
+import org.meshtastic.core.prefs.di.HomoglyphEncodingSharedPreferences
+import javax.inject.Inject
+import javax.inject.Singleton
+
+interface HomoglyphPrefs {
+
+    /** Preference for whether homoglyph encoding is enabled by the user. */
+    var homoglyphEncodingEnabled: Boolean
+
+    /**
+     * Provides a [Flow] that emits the current state of [homoglyphEncodingEnabled] and subsequent changes.
+     *
+     * @return A [Flow] of [Boolean] indicating if homoglyph encoding is enabled.
+     */
+    fun getHomoglyphEncodingEnabledChangesFlow(): Flow<Boolean>
+
+    companion object {
+        /** Key for the homoglyphEncodingEnabled preference. */
+        const val KEY_HOMOGLYPH_ENCODING_ENABLED = "enabled"
+    }
+}
+
+@Singleton
+class HomoglyphPrefsImpl
+@Inject
+constructor(
+    @HomoglyphEncodingSharedPreferences private val homoglyphEncodingSharedPreferences: SharedPreferences,
+) : HomoglyphPrefs {
+    override var homoglyphEncodingEnabled: Boolean by
+        PrefDelegate(homoglyphEncodingSharedPreferences, HomoglyphPrefs.KEY_HOMOGLYPH_ENCODING_ENABLED, false)
+
+    override fun getHomoglyphEncodingEnabledChangesFlow(): Flow<Boolean> = callbackFlow {
+        val listener =
+            SharedPreferences.OnSharedPreferenceChangeListener { _, key ->
+                if (key == HomoglyphPrefs.KEY_HOMOGLYPH_ENCODING_ENABLED) {
+                    trySend(homoglyphEncodingEnabled)
+                }
+            }
+        // Emit the initial value
+        trySend(homoglyphEncodingEnabled)
+        homoglyphEncodingSharedPreferences.registerOnSharedPreferenceChangeListener(listener)
+        awaitClose { homoglyphEncodingSharedPreferences.unregisterOnSharedPreferenceChangeListener(listener) }
+    }
+}

core/strings/src/commonMain/composeResources/values/strings.xml

@@ -294,6 +294,7 @@
     <string name="theme_system">System default</string>
     <string name="choose_theme">Choose theme</string>
     <string name="provide_location_to_mesh">Provide phone location to mesh</string>
+    <string name="use_homoglyph_characters_encoding">Compact encoding for Cyrillic</string>
     <plurals name="delete_messages">
         <item quantity="one">Delete message?</item>
         <item quantity="other">Delete %1$s messages?</item>