Better support for hardware backspace (#281)

* DEL and CLEAR keys now work out-of-the-box, without extra configuration

* removed the DEL and CLEAR hotkey options

res/values/strings.xml

@@ -73,8 +73,6 @@
 	<string name="key_none" translatable="false">--</string>
 	<string name="key_back">Back</string>
 	<string name="key_call">Call</string>
-	<string name="key_clear" translatable="false">Clear</string>
-	<string name="key_delete" translatable="false">Delete</string>
 	<string name="key_menu" translatable="false">Menu</string>
 	<string name="key_soft_left" translatable="false">Left Func</string>
 	<string name="key_soft_right" translatable="false">Right Func</string>

src/io/github/sspanak/tt9/ime/KeyPadHandler.java

@@ -118,10 +118,10 @@ abstract class KeyPadHandler extends InputMethodService {
 
 //		Logger.d("onKeyDown", "Key: " + event + " repeat?: " + event.getRepeatCount() + " long-time: " + event.isLongPress());
 
-		// "backspace" key must repeat its function, when held down, so we handle it in a special way
+		// "backspace" key must repeat its function when held down, so we handle it in a special way
-		if (keyCode == settings.getKeyBackspace()) {
+		if (Key.isBackspace(settings, keyCode)) {
 			// When there is no more text, allow "Back" key to function normally, not to block navigation.
-			// All other keys are blocked, unless it turns out it is annoying this way.
+			// All other keys have their default function disabled.
 			isBackspaceHandled = onBackspace() || keyCode != KeyEvent.KEYCODE_BACK;
 			return isBackspaceHandled;
 		} else {

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

@@ -23,6 +23,7 @@ import io.github.sspanak.tt9.ime.modes.InputMode;
 import io.github.sspanak.tt9.languages.Language;
 import io.github.sspanak.tt9.languages.LanguageCollection;
 import io.github.sspanak.tt9.preferences.SettingsStore;
+import io.github.sspanak.tt9.preferences.helpers.Hotkeys;
 import io.github.sspanak.tt9.ui.UI;
 import io.github.sspanak.tt9.ui.main.MainView;
 import io.github.sspanak.tt9.ui.tray.StatusBar;
@@ -88,7 +89,7 @@ public class TraditionalT9 extends KeyPadHandler {
 
 	private void validateFunctionKeys() {
 		if (settings.isSettingsKeyMissing()) {
-			settings.setDefaultKeys();
+			Hotkeys.setDefault(settings);
 		}
 	}
 

src/io/github/sspanak/tt9/ime/helpers/Key.java

@@ -5,6 +5,14 @@ import android.view.KeyEvent;
 import io.github.sspanak.tt9.preferences.SettingsStore;
 
 public class Key {
+	public static boolean isBackspace(SettingsStore settings, int keyCode) {
+		return
+			keyCode == KeyEvent.KEYCODE_DEL
+			|| keyCode == KeyEvent.KEYCODE_CLEAR
+			|| keyCode == settings.getKeyBackspace();
+	}
+
+
 	public static boolean isNumber(int keyCode) {
 		return
 			(keyCode >= KeyEvent.KEYCODE_0 && keyCode <= KeyEvent.KEYCODE_9)

src/io/github/sspanak/tt9/preferences/PreferencesActivity.java

@@ -18,6 +18,7 @@ import io.github.sspanak.tt9.db.DictionaryDb;
 import io.github.sspanak.tt9.db.DictionaryLoader;
 import io.github.sspanak.tt9.ime.helpers.GlobalKeyboardSettings;
 import io.github.sspanak.tt9.ime.helpers.InputModeValidator;
+import io.github.sspanak.tt9.preferences.helpers.Hotkeys;
 import io.github.sspanak.tt9.preferences.screens.AppearanceScreen;
 import io.github.sspanak.tt9.preferences.screens.DictionariesScreen;
 import io.github.sspanak.tt9.preferences.screens.HotkeysScreen;
@@ -143,7 +144,7 @@ public class PreferencesActivity extends AppCompatActivity implements Preference
 
 	private void validateFunctionKeys() {
 		if (settings.isSettingsKeyMissing()) {
-			settings.setDefaultKeys();
+			Hotkeys.setDefault(settings);
 		}
 	}
 

src/io/github/sspanak/tt9/preferences/SettingsStore.java

@@ -2,7 +2,6 @@ package io.github.sspanak.tt9.preferences;
 
 import android.content.Context;
 import android.content.SharedPreferences;
-import android.view.KeyEvent;
 
 import androidx.preference.PreferenceManager;
 
@@ -161,12 +160,12 @@ public class SettingsStore {
 		return getKeyShowSettings() == 0;
 	}
 
-	public void setDefaultKeys() {
+	public void setDefaultKeys(int addWord, int backspace, int nextInputMode, int nextLanguage, int showSettings) {
-		prefsEditor.putString(SectionKeymap.ITEM_ADD_WORD, String.valueOf(KeyEvent.KEYCODE_STAR));
+		prefsEditor.putString(SectionKeymap.ITEM_ADD_WORD, String.valueOf(addWord));
-		prefsEditor.putString(SectionKeymap.ITEM_BACKSPACE, String.valueOf(KeyEvent.KEYCODE_BACK));
+		prefsEditor.putString(SectionKeymap.ITEM_BACKSPACE, String.valueOf(backspace));
-		prefsEditor.putString(SectionKeymap.ITEM_NEXT_INPUT_MODE, String.valueOf(KeyEvent.KEYCODE_POUND));
+		prefsEditor.putString(SectionKeymap.ITEM_NEXT_INPUT_MODE, String.valueOf(nextInputMode));
-		prefsEditor.putString(SectionKeymap.ITEM_NEXT_LANGUAGE, String.valueOf(-KeyEvent.KEYCODE_POUND));
+		prefsEditor.putString(SectionKeymap.ITEM_NEXT_LANGUAGE, String.valueOf(nextLanguage));
-		prefsEditor.putString(SectionKeymap.ITEM_SHOW_SETTINGS, String.valueOf(-KeyEvent.KEYCODE_STAR));
+		prefsEditor.putString(SectionKeymap.ITEM_SHOW_SETTINGS, String.valueOf(showSettings));
 		prefsEditor.apply();
 	}
 
@@ -181,19 +180,15 @@ public class SettingsStore {
 	public int getKeyAddWord() {
 		return getFunctionKey(SectionKeymap.ITEM_ADD_WORD);
 	}
-
 	public int getKeyBackspace() {
 		return getFunctionKey(SectionKeymap.ITEM_BACKSPACE);
 	}
-
 	public int getKeyNextInputMode() {
 		return getFunctionKey(SectionKeymap.ITEM_NEXT_INPUT_MODE);
 	}
-
 	public int getKeyNextLanguage() {
 		return getFunctionKey(SectionKeymap.ITEM_NEXT_LANGUAGE);
 	}
-
 	public int getKeyShowSettings() {
 		return getFunctionKey(SectionKeymap.ITEM_SHOW_SETTINGS);
 	}

src/io/github/sspanak/tt9/preferences/helpers/Hotkeys.java

@@ -10,6 +10,7 @@ import java.util.LinkedHashMap;
 import java.util.Set;
 
 import io.github.sspanak.tt9.R;
+import io.github.sspanak.tt9.preferences.SettingsStore;
 
 public class Hotkeys {
 	private final Context context;
@@ -39,6 +40,34 @@ public class Hotkeys {
 	}
 
 
+	/**
+	 * setDefault
+	 * Applies the default hotkey scheme.
+	 * When a standard "Backspace" hardware key is available, "Backspace" hotkey association is not necessary,
+	 * so it will be left out blank, to allow the hardware key do its job.
+	 * When the on-screen keyboard is on, "Back" is also not associated, because it will cause weird user
+	 * experience. Instead the on-screen "Backspace" key can be used.
+	 */
+	public static void setDefault(SettingsStore settings) {
+		int backspaceKeyCode = KeyEvent.KEYCODE_BACK;
+		if (
+			KeyCharacterMap.deviceHasKey(KeyEvent.KEYCODE_CLEAR)
+			|| KeyCharacterMap.deviceHasKey(KeyEvent.KEYCODE_DEL)
+			|| settings.getShowSoftNumpad()
+		) {
+			backspaceKeyCode = 0;
+		}
+
+		settings.setDefaultKeys(
+			KeyEvent.KEYCODE_STAR,
+			backspaceKeyCode,
+			KeyEvent.KEYCODE_POUND,
+			-KeyEvent.KEYCODE_POUND,
+			-KeyEvent.KEYCODE_STAR
+		);
+	}
+
+
 	/**
 	 * addIfDeviceHasKey
 	 * Add the key only if Android says the device has such keypad button or a permanent touch key.
@@ -107,8 +136,6 @@ public class Hotkeys {
 		add(KeyEvent.KEYCODE_CALL, R.string.key_call, true);
 
 		addIfDeviceHasKey(KeyEvent.KEYCODE_BACK, R.string.key_back, false);
-		addIfDeviceHasKey(KeyEvent.KEYCODE_CLEAR, R.string.key_clear, false);
-		addIfDeviceHasKey(KeyEvent.KEYCODE_DEL, R.string.key_delete, false);
 		addIfDeviceHasKey(KeyEvent.KEYCODE_F1, "F1", true);
 		addIfDeviceHasKey(KeyEvent.KEYCODE_F2, "F2", true);
 		addIfDeviceHasKey(KeyEvent.KEYCODE_F3, "F3", true);

src/io/github/sspanak/tt9/preferences/items/ItemResetKeys.java

@@ -6,6 +6,7 @@ import androidx.preference.Preference;
 
 import io.github.sspanak.tt9.R;
 import io.github.sspanak.tt9.preferences.SettingsStore;
+import io.github.sspanak.tt9.preferences.helpers.Hotkeys;
 import io.github.sspanak.tt9.ui.UI;
 
 
@@ -26,7 +27,7 @@ public class ItemResetKeys extends ItemClickable {
 
 	@Override
 	protected boolean onClick(Preference p) {
-		settings.setDefaultKeys();
+		Hotkeys.setDefault(settings);
 		dropdowns.reloadSettings();
 		UI.toast(context, R.string.function_reset_keys_done);
 		return true;