Improve behavior for language swipe cycling (#1319)

---------

Co-authored-by: Helium314 <helium314@mailbox.org>

app/src/main/java/helium314/keyboard/keyboard/KeyboardActionListener.java

@@ -97,6 +97,7 @@ public interface KeyboardActionListener {
      */
     boolean onHorizontalSpaceSwipe(int steps);
     boolean onVerticalSpaceSwipe(int steps);
+    void onEndSpaceSwipe();
     boolean toggleNumpad(boolean withSliding, boolean forceReturnToAlpha);
 
     void onMoveDeletePointer(int steps);
@@ -148,6 +149,8 @@ public interface KeyboardActionListener {
             return false;
         }
         @Override
+        public void onEndSpaceSwipe() {}
+        @Override
         public void onMoveDeletePointer(int steps) {}
         @Override
         public void onUpWithDeletePointerActive() {}

app/src/main/java/helium314/keyboard/keyboard/KeyboardActionListenerImpl.kt

@@ -1,6 +1,7 @@
 package helium314.keyboard.keyboard
 
 import android.view.KeyEvent
+import android.view.inputmethod.InputMethodSubtype
 import helium314.keyboard.keyboard.internal.keyboard_parser.floris.KeyCode
 import helium314.keyboard.latin.LatinIME
 import helium314.keyboard.latin.RichInputMethodManager
@@ -19,6 +20,10 @@ class KeyboardActionListenerImpl(private val latinIME: LatinIME, private val inp
     private val settings = Settings.getInstance()
     private var metaState = 0 // is this enough, or are there threading issues with the different PointerTrackers?
 
+    // language slide state
+    private var initialSubtype: InputMethodSubtype? = null
+    private var subtypeSwitchCount = 0
+
     // todo: maybe keep meta state presses to KeyboardActionListenerImpl, and avoid calls to press/release key
     private fun adjustMetaState(code: Int, remove: Boolean) {
         val metaCode = when (code) {
@@ -84,6 +89,11 @@ class KeyboardActionListenerImpl(private val latinIME: LatinIME, private val inp
         else -> false
     }
 
+    override fun onEndSpaceSwipe(){
+        initialSubtype = null
+        subtypeSwitchCount = 0
+    }
+
     override fun toggleNumpad(withSliding: Boolean, forceReturnToAlpha: Boolean): Boolean {
         KeyboardSwitcher.getInstance().toggleNumpad(withSliding, latinIME.currentAutoCapsState, latinIME.currentRecapitalizeState, forceReturnToAlpha)
         return true
@@ -124,7 +134,7 @@ class KeyboardActionListenerImpl(private val latinIME: LatinIME, private val inp
     }
 
     private fun onLanguageSlide(steps: Int): Boolean {
-        if (abs(steps) < 4) return false
+        if (abs(steps) < settings.current.mLanguageSwipeDistance) return false
         val subtypes = RichInputMethodManager.getInstance().getMyEnabledInputMethodSubtypeList(false)
         if (subtypes.size <= 1) { // only allow if we have more than one subtype
             return false
@@ -135,7 +145,18 @@ class KeyboardActionListenerImpl(private val latinIME: LatinIME, private val inp
         wantedIndex %= subtypes.size
         if (wantedIndex < 0)
             wantedIndex += subtypes.size
-        KeyboardSwitcher.getInstance().switchToSubtype(subtypes[wantedIndex])
+        val newSubtype = subtypes[wantedIndex]
+
+        // do not switch if we would switch to the initial subtype after cycling all other subtypes
+        if (initialSubtype == null)
+            initialSubtype = current
+        if (initialSubtype == newSubtype) {
+            if ((subtypeSwitchCount > 0 && steps > 0) || ((subtypeSwitchCount < 0 && steps < 0)))
+                return true
+        }
+        if (steps > 0) subtypeSwitchCount++ else subtypeSwitchCount--
+
+        KeyboardSwitcher.getInstance().switchToSubtype(newSubtype)
         return true
     }
 

app/src/main/java/helium314/keyboard/keyboard/PointerTracker.java

@@ -1076,6 +1076,7 @@ public final class PointerTracker implements PointerTrackerQueue.Element,
             if (mInHorizontalSwipe || mInVerticalSwipe) {
                 mInHorizontalSwipe = false;
                 mInVerticalSwipe = false;
+                sListener.onEndSpaceSwipe();
                 return;
             }
         }

app/src/main/java/helium314/keyboard/latin/settings/AdvancedSettingsFragment.kt

@@ -25,6 +25,7 @@ import androidx.preference.PreferenceManager
 import kotlinx.serialization.encodeToString
 import kotlinx.serialization.json.Json
 import helium314.keyboard.dictionarypack.DictionaryPackConstants
+import helium314.keyboard.keyboard.KeyboardActionListener
 import helium314.keyboard.latin.utils.ChecksumCalculator
 import helium314.keyboard.keyboard.KeyboardLayoutSet
 import helium314.keyboard.keyboard.KeyboardSwitcher
@@ -125,6 +126,8 @@ class AdvancedSettingsFragment : SubScreenFragment() {
         }
         setupKeyLongpressTimeoutSettings()
         setupEmojiSdkSetting()
+        setupLanguageSwipeDistanceSettings()
+        updateLangSwipeDistanceVisibility(sharedPreferences)
         findPreference<Preference>("load_gesture_library")?.setOnPreferenceClickListener { onClickLoadLibrary() }
         findPreference<Preference>("backup_restore")?.setOnPreferenceClickListener { showBackupRestoreDialog() }
 
@@ -560,10 +563,37 @@ class AdvancedSettingsFragment : SubScreenFragment() {
         })
     }
 
+    private fun setupLanguageSwipeDistanceSettings() {
+        val prefs = sharedPreferences
+        findPreference<SeekBarDialogPreference>(Settings.PREF_LANGUAGE_SWIPE_DISTANCE)?.setInterface(object : ValueProxy {
+            override fun writeValue(value: Int, key: String) = prefs.edit().putInt(key, value).apply()
+
+            override fun writeDefaultValue(key: String) = prefs.edit().remove(key).apply()
+
+            override fun readValue(key: String) = Settings.readLanguageSwipeDistance(prefs, resources)
+
+            override fun readDefaultValue(key: String) = Settings.readDefaultLanguageSwipeDistance(resources)
+
+            override fun getValueText(value: Int) = value.toString()
+
+            override fun feedbackValue(value: Int) {}
+        })
+    }
+
+    private fun updateLangSwipeDistanceVisibility(prefs: SharedPreferences) {
+        val horizontalSpaceSwipe = Settings.readHorizontalSpaceSwipe(prefs)
+        val verticalSpaceSwipe = Settings.readVerticalSpaceSwipe(prefs)
+        val visibility = horizontalSpaceSwipe == KeyboardActionListener.SWIPE_SWITCH_LANGUAGE
+                || verticalSpaceSwipe == KeyboardActionListener.SWIPE_SWITCH_LANGUAGE
+        setPreferenceVisible(Settings.PREF_LANGUAGE_SWIPE_DISTANCE, visibility)
+    }
+
     override fun onSharedPreferenceChanged(prefs: SharedPreferences, key: String?) {
         when (key) {
             Settings.PREF_SHOW_SETUP_WIZARD_ICON -> SystemBroadcastReceiver.toggleAppIcon(requireContext())
             Settings.PREF_MORE_POPUP_KEYS -> KeyboardLayoutSet.onSystemLocaleChanged()
+            Settings.PREF_SPACE_HORIZONTAL_SWIPE -> updateLangSwipeDistanceVisibility(prefs)
+            Settings.PREF_SPACE_VERTICAL_SWIPE -> updateLangSwipeDistanceVisibility(prefs)
             Settings.PREF_EMOJI_MAX_SDK -> KeyboardSwitcher.getInstance().forceUpdateKeyboardTheme(requireContext())
         }
     }

app/src/main/java/helium314/keyboard/latin/settings/Settings.java

@@ -157,6 +157,7 @@ public final class Settings implements SharedPreferences.OnSharedPreferenceChang
     public static final String PREF_MORE_POPUP_KEYS = "more_popup_keys";
 
     public static final String PREF_SPACE_TO_CHANGE_LANG = "prefs_long_press_keyboard_to_change_lang";
+    public static final String PREF_LANGUAGE_SWIPE_DISTANCE = "language_swipe_distance";
 
     public static final String PREF_ENABLE_CLIPBOARD_HISTORY = "enable_clipboard_history";
     public static final String PREF_CLIPBOARD_HISTORY_RETENTION_TIME = "clipboard_history_retention_time";
@@ -453,6 +454,18 @@ public final class Settings implements SharedPreferences.OnSharedPreferenceChang
         };
     }
 
+    public static int readLanguageSwipeDistance(final SharedPreferences prefs,
+                                                final Resources res) {
+        final int sensitivity = prefs.getInt(
+                PREF_LANGUAGE_SWIPE_DISTANCE, UNDEFINED_PREFERENCE_VALUE_INT);
+        return (sensitivity != UNDEFINED_PREFERENCE_VALUE_INT) ? sensitivity
+                : readDefaultLanguageSwipeDistance(res);
+    }
+
+    public static int readDefaultLanguageSwipeDistance(final Resources res) {
+        return 5;
+    }
+
     public static boolean readDeleteSwipeEnabled(final SharedPreferences prefs) {
         return prefs.getBoolean(PREF_DELETE_SWIPE, true);
     }

app/src/main/java/helium314/keyboard/latin/settings/SettingsValues.java

@@ -81,6 +81,7 @@ public class SettingsValues {
     public final boolean mBlockPotentiallyOffensive;
     public final int mSpaceSwipeHorizontal;
     public final int mSpaceSwipeVertical;
+    public final int mLanguageSwipeDistance;
     public final boolean mDeleteSwipeEnabled;
     public final boolean mAutospaceAfterPunctuationEnabled;
     public final boolean mClipboardHistoryEnabled;
@@ -232,6 +233,7 @@ public class SettingsValues {
         mDisplayOrientation = res.getConfiguration().orientation;
         mSpaceSwipeHorizontal = Settings.readHorizontalSpaceSwipe(prefs);
         mSpaceSwipeVertical = Settings.readVerticalSpaceSwipe(prefs);
+        mLanguageSwipeDistance = Settings.readLanguageSwipeDistance(prefs, res);
         mDeleteSwipeEnabled = Settings.readDeleteSwipeEnabled(prefs);
         mAutospaceAfterPunctuationEnabled = Settings.readAutospaceAfterPunctuationEnabled(prefs);
         mClipboardHistoryEnabled = Settings.readClipboardHistoryEnabled(prefs);

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

@@ -377,6 +377,7 @@
     <string name="prefs_long_press_symbol_for_numpad">নম্বর প্যাডের জন্য প্রতীক বোতামে দীর্ঘ চাপ</string>
     <string name="var_toolbar_direction">টুলবারের পরিবর্তনশীল দিক</string>
     <string name="var_toolbar_direction_summary">ডান থেকে বাম কিবোর্ড নির্বাচন করলে দিক বিপরীত হবে</string>
+    <string name="prefs_language_swipe_distance">ভাষা পরিবর্তন অভিস্পর্শের দূরত্ব</string>
     <string name="subtype_generic_student"><xliff:g id="LANGUAGE_NAME" example="Russian">%s</xliff:g> (শিক্ষার্থী)</string>
     <string name="language_switch_key_behavior">ভাষা পরিবর্তন বোতামের আচরণ</string>
     <string name="pinned_toolbar_keys">পিন করে রাখা টুলবার বোতাম নির্বাচন</string>

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

@@ -958,6 +958,8 @@ New dictionary:
     <string name="var_toolbar_direction">Variable toolbar direction</string>
     <!-- Description of the variable toolbar direction setting -->
     <string name="var_toolbar_direction_summary">Reverse direction when a right-to-left keyboard subtype is selected</string>
+    <!-- Title of the settings for adjusting the language swipe gesture distance -->
+    <string name="prefs_language_swipe_distance">Switch language swipe distance</string>
     <!-- Title of the setting to customize toolbar key codes -->
     <string name="customize_toolbar_key_codes">Customize toolbar key codes</string>
     <!-- Confirmation message when resetting all custom toolbar key codes -->

app/src/main/res/xml/prefs_screen_advanced.xml

@@ -43,6 +43,13 @@
         android:title="@string/show_vertical_space_swipe"
         latin:singleLineTitle="false" />
 
+    <helium314.keyboard.latin.settings.SeekBarDialogPreference
+        android:key="language_swipe_distance"
+        android:title="@string/prefs_language_swipe_distance"
+        latin:minValue="2"
+        latin:maxValue="18"
+        latin:stepValue="1" />
+
     <SwitchPreference
         android:key="delete_swipe"
         android:title="@string/delete_swipe"