feat: support localehints hints when provided for textviews

java/res/values/strings.xml

@@ -77,6 +77,13 @@
     <!-- Description for "next word suggestion" option. This displays suggestions even when there is no input, based on the previous word. -->
     <string name="bigram_prediction_summary">Use the previous word in making suggestions</string>
 
+    <!-- Title for auto-switch language setting -->
+    <string name="auto_switch_language_title">Auto-switch language</string>
+    <!-- Subtitle for auto-switch language setting -->
+    <string name="auto_switch_language_subtitle">Automatically switch to a matching language if the text field requests it (e.g. Translate)</string>
+    <!-- Title for advanced language settings section -->
+    <string name="language_settings_advanced_options">Advanced options</string>
+
     <!-- Title for input language selection screen -->
     <string name="language_selection_title">Languages</string>
 

java/src/org/futo/inputmethod/latin/InputAttributes.java

@@ -20,6 +20,7 @@
 import static org.futo.inputmethod.latin.common.Constants.ImeOption.NO_MICROPHONE;
 import static org.futo.inputmethod.latin.common.Constants.ImeOption.NO_MICROPHONE_COMPAT;
 
+import android.os.LocaleList;
 import android.text.InputType;
 import android.util.Log;
 import android.view.inputmethod.EditorInfo;
@@ -56,6 +57,8 @@ public final class InputAttributes {
     final public Locale mLocaleOverride;
     @Nullable
     final public String mLayoutOverride;
+    @Nullable
+    final public LocaleList mHintLocales;
 
     /**
      * Whether the floating gesture preview should be disabled. If true, this should override the
@@ -111,6 +114,7 @@ public InputAttributes(final EditorInfo editorInfo, final boolean isFullscreenMo
             mIsWebField = false;
             mLocaleOverride = null;
             mLayoutOverride = null;
+            mHintLocales = null;
             return;
         }
         // inputClass == InputType.TYPE_CLASS_TEXT
@@ -191,6 +195,7 @@ public InputAttributes(final EditorInfo editorInfo, final boolean isFullscreenMo
         }
 
         mLayoutOverride = privateImeOptions.get("org.futo.inputmethod.latin.ForceLayout");
+        mHintLocales = editorInfo.hintLocales;
     }
 
     public boolean isTypeNull() {

java/src/org/futo/inputmethod/latin/LatinIME.kt

@@ -306,6 +306,50 @@ class LatinIME : InputMethodServiceCompose(), LatinIMELegacy.SuggestionStripCont
         }
     }
 
+    private fun updateKeyboardLanguage() {
+        val settings = latinIMELegacy.mSettings.current
+        if (!settings.mAutoSwitchLanguage) return
+
+        val hintLocales = settings.mInputAttributes.mHintLocales ?: return
+        if (hintLocales.isEmpty) return
+
+        // We need to read these right from the settings. LatinIME just seems to return a generic "keyboard" subtype
+        // with no language info when you get subtypes from InputMethodManager
+        val enabledSubtypes = getSettingBlocking(SubtypesSetting).map(Subtypes::convertToSubtype)
+        if (enabledSubtypes.isEmpty()) return
+
+        val currentSubtype = RichInputMethodManager.getInstance().currentSubtype.rawSubtype
+        val currentSubtypeString = Subtypes.subtypeToString(currentSubtype)
+        val currentLanguage = Subtypes.getLocale(currentSubtype).language
+        val hintedLocales = (0 until hintLocales.size()).map(hintLocales::get)
+
+        if (hintedLocales.any { it.language == currentLanguage }) {
+            // Some apps update hintLocales faster than keyboard view state settles.
+            // If the current language is already valid for hints, keep it but force one UI resync.
+            // Example is changing between JP/EN in translate, going from 12 key back to EN would not work correctly. 
+            if (lastAutoSwitchResyncSubtype != currentSubtypeString) {
+                latinIMELegacy.onCurrentInputMethodSubtypeChanged(currentSubtype)
+                lastAutoSwitchResyncSubtype = currentSubtypeString
+            }
+            return
+        }
+
+        // checking subtypes by tag and fallback to language if none found
+        val targetSubtype = hintedLocales.firstNotNullOfOrNull { hintLocale ->
+            enabledSubtypes.find {
+                Subtypes.getLocale(it).toLanguageTag().equals(hintLocale.toLanguageTag(), true)
+            } ?: enabledSubtypes.find {
+                val subtypeLocale = Subtypes.getLocale(it)
+                subtypeLocale.language.isNotEmpty() && subtypeLocale.language == hintLocale.language
+            }
+        } ?: return
+
+        if (Subtypes.subtypeToString(targetSubtype) == currentSubtypeString) return
+
+        lastAutoSwitchResyncSubtype = ""
+        latinIMELegacy.onCurrentInputMethodSubtypeChanged(targetSubtype)
+    }
+
     fun onSizeUpdated() {
         val newSize = calculateSize() ?: return
         val shouldInvalidateKeyboard = size.value?.let { oldSize ->
@@ -350,6 +394,7 @@ class LatinIME : InputMethodServiceCompose(), LatinIMELegacy.SuggestionStripCont
     }
 
     private var currentSubtype = ""
+    private var lastAutoSwitchResyncSubtype = ""
 
     val jobs = mutableListOf<Job>()
     private fun launchJob(task: suspend CoroutineScope.() -> Unit) {
@@ -592,6 +637,7 @@ class LatinIME : InputMethodServiceCompose(), LatinIMELegacy.SuggestionStripCont
         latinIMELegacy.onStartInputView(info, restarting)
         lifecycleScope.launch { uixManager.showUpdateNoticeIfNeeded() }
         updateColorsIfDynamicChanged()
+        updateKeyboardLanguage()
     }
 
     override fun onFinishInputView(finishingInput: Boolean) {

java/src/org/futo/inputmethod/latin/LatinIMELegacy.java

@@ -343,7 +343,9 @@ public void onCurrentInputMethodSubtypeChanged(final InputMethodSubtype subtype)
     }
 
     void onStartInputInternal(final EditorInfo editorInfo, final boolean restarting) {
-
+        // Refresh InputAttributes even when restarting in the same field. Some apps
+        // (e.g Translate) update hintLocales but not inputType, leading to out of date hintLocales
+        loadSettings();
     }
 
     public void updateMainKeyboardViewSettings() {

java/src/org/futo/inputmethod/latin/settings/Settings.java

@@ -145,6 +145,8 @@ public final class Settings implements SharedPreferences.OnSharedPreferenceChang
 
     public static final int DEFAULT_ALT_SPACES_MODE = SPACES_MODE_ALL;
 
+    public static final String PREF_AUTO_SWITCH_LANGUAGE = "pref_auto_switch_language";
+
     // Emoji
     public static final String PREF_EMOJI_RECENT_KEYS = "emoji_recent_keys";
     public static final String PREF_EMOJI_CATEGORY_LAST_TYPED_ID = "emoji_category_last_typed_id";

java/src/org/futo/inputmethod/latin/settings/SettingsValues.java

@@ -106,7 +106,8 @@ public class SettingsValues {
     public final int mBackspaceMode;
     public final int mNumberRowMode;
     public final int mAltSpacesMode;
-
+    public final boolean mAutoSwitchLanguage;
+
     // From the input box
     @Nonnull
     public final InputAttributes mInputAttributes;
@@ -201,9 +202,10 @@ public SettingsValues(final Context context, final SharedPreferences prefs, fina
                 prefs.getInt(Settings.PREF_NUMBER_ROW_MODE, Settings.NUMBER_ROW_MODE_DEFAULT)
                 : Settings.NUMBER_ROW_MODE_DEFAULT;
         mAltSpacesMode = prefs.getInt(Settings.PREF_ALT_SPACES_MODE, Settings.DEFAULT_ALT_SPACES_MODE);
+        mAutoSwitchLanguage = prefs.getBoolean(Settings.PREF_AUTO_SWITCH_LANGUAGE, false);
 
         mShouldShowLxxSuggestionUi = Settings.SHOULD_SHOW_LXX_SUGGESTION_UI
-                && prefs.getBoolean(DebugSettings.PREF_SHOULD_SHOW_LXX_SUGGESTION_UI, true);
+               && prefs.getBoolean(DebugSettings.PREF_SHOULD_SHOW_LXX_SUGGESTION_UI, true);
         // Compute other readable settings
         mKeyLongpressTimeout = Settings.readKeyLongpressTimeout(prefs, res);
         mKeypressVibrationDuration = Settings.readKeypressVibrationDuration(prefs, res);

java/src/org/futo/inputmethod/latin/uix/settings/pages/Languages.kt

@@ -52,6 +52,7 @@ import org.futo.inputmethod.latin.MultilingualBucketSetting
 import org.futo.inputmethod.latin.R
 import org.futo.inputmethod.latin.Subtypes
 import org.futo.inputmethod.latin.SubtypesSetting
+import org.futo.inputmethod.latin.settings.Settings
 import org.futo.inputmethod.latin.uix.FileKind
 import org.futo.inputmethod.latin.uix.ResourceHelper
 import org.futo.inputmethod.latin.uix.getSetting
@@ -66,6 +67,7 @@ import org.futo.inputmethod.latin.uix.settings.pages.modelmanager.openModelImpor
 import org.futo.inputmethod.latin.uix.settings.useDataStore
 import org.futo.inputmethod.latin.uix.settings.useDataStoreValue
 import org.futo.inputmethod.latin.uix.settings.userSettingNavigationItem
+import org.futo.inputmethod.latin.uix.settings.userSettingToggleSharedPrefs
 import org.futo.inputmethod.latin.uix.theme.Typography
 import org.futo.inputmethod.latin.uix.theme.UixThemeWrapper
 import org.futo.inputmethod.latin.uix.theme.presets.DynamicDarkTheme
@@ -507,6 +509,16 @@ val LanguageSettingsTop = listOf(
         navigateTo = "addLanguage",
     )
 )
+
+val LanguageSettingsToggles = listOf(
+    userSettingToggleSharedPrefs(
+        title = R.string.auto_switch_language_title,
+        subtitle = R.string.auto_switch_language_subtitle,
+        key = Settings.PREF_AUTO_SWITCH_LANGUAGE,
+        default = { false }
+    )
+)
+
 val LanguageSettingsBottom = listOf(
     userSettingNavigationItem(
         title = R.string.language_settings_import_resource_from_file,
@@ -750,5 +762,13 @@ fun LanguagesScreen(navController: NavHostController = rememberNavController())
         items(LanguageSettingsBottom) {
             it.component()
         }
+
+        item {
+            ScreenTitle(stringResource(R.string.language_settings_advanced_options))
+        }
+
+        items(LanguageSettingsToggles) {
+            it.component()
+        }
     }
 }

tests/src/org/futo/inputmethod/latin/InputAttributesTests.java

@@ -0,0 +1,29 @@
+package org.futo.inputmethod.latin;
+
+import android.os.LocaleList;
+import android.view.inputmethod.EditorInfo;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.runners.MockitoJUnitRunner;
+
+import java.util.Locale;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+@RunWith(MockitoJUnitRunner.class)
+public class InputAttributesTests {
+
+    @Test
+    public void testHintLocales() {
+        final EditorInfo editorInfo = mock(EditorInfo.class);
+        final LocaleList localeList = new LocaleList(new Locale("en", "US"), new Locale("ja", "JP"));
+        when(editorInfo.getHintLocales()).thenReturn(localeList);
+
+        final InputAttributes inputAttributes = new InputAttributes(editorInfo, false, "");
+
+        assertEquals(localeList, inputAttributes.mHintLocales);
+    }
+}