workaround for getTextBeforeCursor() taking too much time and causing unresponsive UI

app/src/main/java/io/github/sspanak/tt9/ime/TraditionalT9.java

@@ -9,6 +9,7 @@ import android.view.inputmethod.InputConnection;
 
 import androidx.annotation.NonNull;
 
+import io.github.sspanak.tt9.R;
 import io.github.sspanak.tt9.db.DataStore;
 import io.github.sspanak.tt9.db.words.DictionaryLoader;
 import io.github.sspanak.tt9.hacks.InputType;
@@ -237,21 +238,35 @@ public class TraditionalT9 extends MainViewHandler {
 		Logger.d(LOG_TAG, "===> Shutdown completed");
 	}
 
+
 	@Override
 	public void onTimeout(int startId) {
 		onZombie();
 		super.onTimeout(startId);
 	}
 
+
 	@Override
 	protected boolean onNumber(int key, boolean hold, int repeat) {
 		if (InputModeKind.isPredictive(mInputMode) && DictionaryLoader.autoLoad(this, mLanguage)) {
 			return true;
 		}
+		if (textField.shouldReportConnectionErrors()) {
+			UI.toastLongSingle(getApplicationContext(), R.string.error_unstable_input_connection);
+		}
 		return super.onNumber(key, hold, repeat);
 	}
 
 
+	@Override
+	public boolean onBackspace(int repeat) {
+		if (textField.shouldReportConnectionErrors()) {
+			UI.toastLongSingle(getApplicationContext(), R.string.error_unstable_input_connection);
+		}
+		return super.onBackspace(repeat);
+	}
+
+
 	@Override
 	protected TraditionalT9 getFinalContext() {
 		return this;

app/src/main/java/io/github/sspanak/tt9/ime/helpers/InputField.java

@@ -14,11 +14,11 @@ import io.github.sspanak.tt9.languages.LanguageCollection;
 public class InputField {
 	public static final int IME_ACTION_ENTER = EditorInfo.IME_MASK_ACTION + 1;
 
-	protected final InputConnection connection;
+	@Nullable protected final InputConnection connection;
-	protected final EditorInfo field;
+	@Nullable protected final EditorInfo field;
 
 
-	protected InputField(InputConnection inputConnection, EditorInfo inputField) {
+	protected InputField(@Nullable InputConnection inputConnection, @Nullable EditorInfo inputField) {
 		connection = inputConnection;
 		field = inputField;
 	}
@@ -85,11 +85,11 @@ public class InputField {
 	 */
 	@Nullable
 	public Language getLanguage(ArrayList<Integer> allowedLanguageIds) {
-		if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N) {
+		if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N || field == null || field.hintLocales == null) {
 			return null;
 		}
 
-		for (int i = 0; field.hintLocales != null && i < field.hintLocales.size(); i++) {
+		for (int i = 0; i < field.hintLocales.size(); i++) {
 			Language lang = LanguageCollection.getByLanguageCode(field.hintLocales.get(i).getLanguage());
 			if (lang != null && allowedLanguageIds.contains(lang.getId())) {
 				return lang;

app/src/main/java/io/github/sspanak/tt9/ime/helpers/TextField.java

@@ -18,10 +18,13 @@ import io.github.sspanak.tt9.ime.modes.InputMode;
 import io.github.sspanak.tt9.languages.Language;
 import io.github.sspanak.tt9.languages.LanguageKind;
 import io.github.sspanak.tt9.preferences.settings.SettingsStore;
+import io.github.sspanak.tt9.util.InputConnectionTools;
 import io.github.sspanak.tt9.util.Logger;
 import io.github.sspanak.tt9.util.Text;
 
 public class TextField extends InputField {
+	@NonNull private final InputConnectionTools connectionTools;
+
 	private CharSequence composingText = "";
 	private final boolean isComposingSupported;
 	private final boolean isNonText;
@@ -30,6 +33,8 @@ public class TextField extends InputField {
 	public TextField(InputConnection inputConnection, EditorInfo inputField) {
 		super(inputConnection, inputField);
 
+		connectionTools = new InputConnectionTools(inputConnection);
+
 		InputType inputType = new InputType(inputConnection, inputField);
 		isComposingSupported = !inputType.isNumeric() && !inputType.isLimited() && !inputType.isRustDesk() && !inputType.isDeezerSearchBar();
 		isNonText = !inputType.isText();
@@ -37,14 +42,14 @@ public class TextField extends InputField {
 
 
 	public String getStringAfterCursor(int numberOfChars) {
-		CharSequence character = connection != null ? connection.getTextAfterCursor(numberOfChars, 0) : null;
+		CharSequence chars = connectionTools.getTextAfterCursor(numberOfChars, 0);
-		return character != null ? character.toString() : "";
+		return chars != null ? chars.toString() : "";
 	}
 
 
 	public String getStringBeforeCursor(int numberOfChars) {
-		CharSequence character = connection != null ? connection.getTextBeforeCursor(numberOfChars, 0) : null;
+		CharSequence chars = connectionTools.getTextBeforeCursor(numberOfChars, 0);
-		return character != null ? character.toString() : "";
+		return chars != null ? chars.toString() : "";
 	}
 
 
@@ -206,7 +211,7 @@ public class TextField extends InputField {
 		String searchText = " " + word;
 
 		connection.beginBatchEdit();
-		CharSequence beforeText = connection.getTextBeforeCursor(searchText.length(), 0);
+		String beforeText = getStringBeforeCursor(searchText.length());
 		if (beforeText == null || !beforeText.equals(searchText)) {
 			connection.endBatchEdit();
 			return;
@@ -229,7 +234,7 @@ public class TextField extends InputField {
 		}
 
 		connection.beginBatchEdit();
-		CharSequence beforeText = connection.getTextBeforeCursor(word.length(), 0);
+		String beforeText = getStringBeforeCursor(word.length());
 		if (beforeText == null || !beforeText.equals(word)) {
 			connection.endBatchEdit();
 			return;
@@ -391,4 +396,9 @@ public class TextField extends InputField {
 
 		return false;
 	}
+
+
+	public boolean shouldReportConnectionErrors() {
+		return connectionTools.shouldReportTimeout();
+	}
 }

app/src/main/java/io/github/sspanak/tt9/preferences/settings/SettingsStore.java

@@ -18,6 +18,8 @@ public class SettingsStore extends SettingsUI {
 	public final static int DICTIONARY_DOWNLOAD_READ_TIMEOUT = 10000; // ms
 	public final static int DICTIONARY_IMPORT_BATCH_SIZE = 5000; // words
 	public final static int DICTIONARY_IMPORT_PROGRESS_UPDATE_TIME = 250; // ms
+	public final static int INPUT_CONNECTION_ERRORS_MAX = 3;
+	public final static int INPUT_CONNECTION_OPERATIONS_TIMEOUT = 150; // ms
 	public final static int RESIZE_THROTTLING_TIME = 60; // ms
 	public final static byte SLOW_QUERY_TIME = 50; // ms
 	public final static int SLOW_QUERY_TIMEOUT = 3000; // ms

app/src/main/java/io/github/sspanak/tt9/ui/UI.java

@@ -97,7 +97,7 @@ public class UI {
 		toastLong(context, msg);
 	}
 
-	public static void toastShortSingle(@NonNull Context context, @NonNull String uniqueId, @NonNull String message) {
+	public static void toastSingle(@NonNull Context context, @NonNull String uniqueId, @NonNull String message, boolean isShort) {
 		Toast toast = singleToasts.get(uniqueId);
 
 		if (toast != null) {
@@ -105,14 +105,21 @@ public class UI {
 		}
 
 		// we recreate the toast, because if set new text, when it is fading out, it is ignored
-		toast = Toast.makeText(context, message, Toast.LENGTH_SHORT);
+		toast = Toast.makeText(context, message, isShort ? Toast.LENGTH_SHORT : Toast.LENGTH_LONG);
 		toast.show();
 
 		singleToasts.put(uniqueId, toast);
 	}
 
+	public static void toastShortSingle(@NonNull Context context, @NonNull String uniqueId, @NonNull String message) {
+		toastSingle(context, uniqueId, message, true);
+	}
 
 	public static void toastShortSingle(@NonNull Context context, int resourceId) {
-		toastShortSingle(context, String.valueOf(resourceId), context.getString(resourceId));
+		toastSingle(context, String.valueOf(resourceId), context.getString(resourceId), true);
+	}
+
+	public static void toastLongSingle(@NonNull Context context, int resourceId) {
+		toastSingle(context, String.valueOf(resourceId), context.getString(resourceId), false);
 	}
 }

app/src/main/java/io/github/sspanak/tt9/util/InputConnectionTools.java

@@ -0,0 +1,95 @@
+package io.github.sspanak.tt9.util;
+
+import android.os.Build;
+import android.view.inputmethod.InputConnection;
+
+import androidx.annotation.Nullable;
+import androidx.annotation.RequiresApi;
+
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+import io.github.sspanak.tt9.preferences.settings.SettingsStore;
+
+public class InputConnectionTools {
+	@Nullable private final InputConnection connection;
+	private int connectionErrors;
+	private boolean isErrorReported;
+
+
+	public InputConnectionTools(@Nullable InputConnection connection) {
+		this.connection = connection;
+		connectionErrors = 0;
+		isErrorReported = false;
+	}
+
+
+	public CharSequence getTextAfterCursor(int i, int ii) {
+		return getTextNextToCursor(i, ii, true);
+	}
+
+
+	public CharSequence getTextBeforeCursor(int i, int ii) {
+		return getTextNextToCursor(i, ii, false);
+	}
+
+
+	@Nullable
+	private CharSequence getTextNextToCursor(int i, int ii, boolean after) {
+		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
+			return getTextNextToCursorModern(i, ii, after);
+		} else {
+			return getTextNextToCursorClassic(i, ii, after);
+		}
+	}
+
+
+	private CharSequence getTextNextToCursorClassic(int i, int ii, boolean after) {
+		if (connection == null) {
+			return null;
+		}
+
+		return after ? connection.getTextAfterCursor(i, ii) : connection.getTextBeforeCursor(i, ii);
+	}
+
+
+	/**
+	 * getTextNextToCursorModern
+	 * On some devices with Android >= 11, getTextBeforeCursor() sometimes takes too long to execute,
+	 * blocking the UI thread and ultimately causing ANR. This method is a wrapper around
+	 * getTextBeforeCursor() that terminates the operations after a certain timeout. Just in case we
+	 * handle getTextAfterCursor() the same way.
+	 */
+	@Nullable
+	@RequiresApi(api = Build.VERSION_CODES.N)
+	private CharSequence getTextNextToCursorModern(int i, int ii, boolean after) {
+		CompletableFuture<CharSequence> future = CompletableFuture.supplyAsync(
+			() -> getTextNextToCursorClassic(i, ii, after)
+		);
+
+		try {
+			return future.get(SettingsStore.INPUT_CONNECTION_OPERATIONS_TIMEOUT, TimeUnit.MILLISECONDS);
+		} catch (TimeoutException e) {
+			connectionErrors++;
+			Logger.e(
+				getClass().getSimpleName(),
+				"getStringBeforeCursor() timed out after " + SettingsStore.INPUT_CONNECTION_OPERATIONS_TIMEOUT + "ms. " + connectionErrors + " errors so far."
+			);
+			return null;
+		} catch (InterruptedException | ExecutionException e) {
+			connectionErrors++;
+			Logger.e(getClass().getSimpleName(), "getStringBeforeCursor() failed " + connectionErrors + " times so far. Current error: " + e);
+			return null;
+		}
+	}
+
+	public boolean shouldReportTimeout() {
+		if (!isErrorReported && connectionErrors > SettingsStore.INPUT_CONNECTION_ERRORS_MAX) {
+			isErrorReported = true;
+			return true;
+		}
+		return false;
+	}
+}

app/src/main/res/values-bg/strings.xml

@@ -5,6 +5,7 @@
 	<string name="completed">Завършено</string>
 	<string name="loading">Зареждане…</string>
 	<string name="error_unexpected">Възникна неочаквана грешка.</string>
+	<string name="error_unstable_input_connection">Нестабилна връзка с приложението!</string>
 	<string name="add_word_add">Добави</string>
 	<string name="add_word_no_selection">Преместете показалеца върху дума, за да я добавите към речника.</string>
 	<string name="add_word_blank">Не може да се въведе празна дума.</string>

app/src/main/res/values-de/strings.xml

@@ -4,6 +4,7 @@
 	<string name="loading">Laden…</string>
 	<string name="error_unexpected">Unerwarteter Fehler aufgetreten.</string>
 
+	<string name="error_unstable_input_connection">Instabile Anwendungsverbindung!</string>
 	<string name="add_word_add">Hinzufügen</string>
 	<string name="add_word_confirm">Wort \"%1$s\" zu %2$s hinzufügen?</string>
 	<string name="add_word_no_selection">Bewegen Sie den Cursor innerhalb eines Wortes, um es hinzuzufügen.</string>

app/src/main/res/values-es/strings.xml

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
 	<string name="app_settings">Configuración de Traditional T9</string>
+	<string name="error_unstable_input_connection">¡Conexión inestable con la aplicación!</string>
 	<string name="add_word_add">Agregar</string>
 	<string name="add_word_confirm">¿Agregar la palabra \"%1$s\" a %2$s?</string>
 	<string name="add_word_no_selection">Mueve el cursor dentro de una palabra para añadirla.</string>

app/src/main/res/values-fr/strings.xml

@@ -5,6 +5,7 @@
 	<string name="completed">Fini</string>
 	<string name="loading">Chargement…</string>
 	<string name="error_unexpected">Une erreur inattendue s\'est produite.</string>
+	<string name="error_unstable_input_connection">Connexion instable à l\'application !</string>
 	<string name="add_word_add">Ajouter</string>
 	<string name="add_word_no_selection">Déplacez le curseur dans un mot pour l\'ajouter.</string>
 	<string name="add_word_blank">Mot vide non ajouté.</string>

app/src/main/res/values-it/strings.xml

@@ -6,6 +6,7 @@
 	<string name="loading">Caricamento…</string>
 	<string name="error_unexpected">Si è verificato un errore imprevisto.</string>
 
+	<string name="error_unstable_input_connection">Connessione instabile all\'applicazione!</string>
 	<string name="add_word_add">Aggiungere</string>
 	<string name="add_word_confirm">Aggiungi la parola \"%1$s\" a %2$s?</string>
 	<string name="add_word_no_selection">Sposta il cursore dentro un parola per aggiungerla.</string>

app/src/main/res/values-iw/strings.xml

@@ -6,6 +6,7 @@
 	<string name="loading">טוען…</string>
 	<string name="error_unexpected">אירעה שגיאה לא צפויה.</string>
 
+	<string name="error_unstable_input_connection">חיבור לא יציב לאפליקציה!</string>
 	<string name="add_word_add">הוסף</string>
 	<string name="add_word_confirm">האם להוסיף את המילה \"%1$s\" ל-%2$s?</string>
 	<string name="add_word_no_selection">הזיזו את הסמן בתוך מילה כדי להוסיף אותה.</string>

app/src/main/res/values-lt/strings.xml

@@ -7,6 +7,7 @@
 
 	<string name="error_unexpected">Įvyko netikėta klaida.</string>
 
+	<string name="error_unstable_input_connection">Nestabilus programėlės ryšys!</string>
 	<string name="add_word_add">Pridėti</string>
 	<string name="add_word_confirm">Pridėti žodį \"%1$s\" į \"%2$s\" žodyną?</string>
 	<string name="add_word_no_selection">Perkelkite žymeklį prie žodžio kurį norite pridėti.</string>

app/src/main/res/values-nl/strings.xml

@@ -4,6 +4,7 @@
 	<string name="loading">Laden…</string>
 	<string name="error_unexpected">Er is een onverwachte fout opgetreden.</string>
 
+	<string name="error_unstable_input_connection">Onstabiele applicatieverbinding!</string>
 	<string name="add_word_add">Toevoegen</string>
 	<string name="add_word_confirm">Voeg woord \"%1$s\" toe aan %2$s?</string>
 	<string name="add_word_no_selection">Verplaats de cursor binnen een woord om het toe te voegen.</string>

app/src/main/res/values-pt-rBR/strings.xml

@@ -6,6 +6,7 @@
 	<string name="loading">Carregando…</string>
 	<string name="error_unexpected">Um erro inesperado aconteceu.</string>
 
+	<string name="error_unstable_input_connection">Conexão instável com o aplicativo!</string>
 	<string name="add_word_add">Adicionar</string>
 	<string name="add_word_confirm">Adicionar a palavra \"%1$s\" a %2$s?</string>
 	<string name="add_word_no_selection">Mova o cursor dentro de uma palavra para adicioná-la.</string>

app/src/main/res/values-ru/strings.xml

@@ -5,6 +5,7 @@
 	<string name="completed">Выполнено</string>
 	<string name="loading">Загрузка…</string>
 	<string name="error_unexpected">Произошла непредвиденная ошибка.</string>
+	<string name="error_unstable_input_connection">Нестабильное соединение с приложением!</string>
 	<string name="add_word_add">Добавить</string>
 	<string name="add_word_no_selection">Переместите курсор внутрь слова, чтобы добавить его.</string>
 	<string name="add_word_blank">Невозможно добавить слово.</string>

app/src/main/res/values-tr/strings.xml

@@ -4,6 +4,7 @@
 	<string name="loading">Yükleniyor…</string>
 	<string name="error_unexpected">Beklenmeyen bir hata ile karşılaşıldı.</string>
 
+	<string name="error_unstable_input_connection">Uygulama bağlantısı kararsız!</string>
 	<string name="add_word_add">Ekle</string>
 	<string name="add_word_confirm">\"%1$s\" kelimesi %2$s sözlüğe eklensin mi?</string>
 	<string name="add_word_no_selection">Ekleme yapmak için imleci eklemek istediğiniz kelimeye götürün.</string>

app/src/main/res/values-uk/strings.xml

@@ -7,6 +7,7 @@
 
 	<string name="error_unexpected">Сталася неочікувана помилка.</string>
 
+	<string name="error_unstable_input_connection">Нестабільне з\'єднання з додатком!</string>
 	<string name="add_word_add">Додати</string>
 	<string name="add_word_confirm">Додати слово \"%1$s\" в %2$s?</string>
 	<string name="add_word_no_selection">Перемістіть курсор у слово, щоб додати його.</string>

app/src/main/res/values/strings.xml

@@ -11,6 +11,7 @@
 	<string name="search_results_void">No results.</string>
 
 	<string name="error_unexpected">Unexpected error occurred.</string>
+	<string name="error_unstable_input_connection">Unstable application connection!</string>
 
 	<string name="add_word_add">Add</string>
 	<string name="add_word_confirm">Add word \"%1$s\" to %2$s?</string>