Fix slider movements changing input focus

The slider was repeatedly sending arrow keys, which change the focused
input when the end of a text box is hit.

A new key is added that implements cursor movements using the
`InputConnection` API.
The new keys are defined as `KeyValue.Editing`, which are no longer only
context menu actions.

The behavior when a selection has started is changed. The selection is
modified instead of cleared even when shift isn't pressed or the
selection would become empty.

Fallbacks to sending arrow keys for editors that do not support the API,
like Termux.

1 files changed, 88 insertions, 28 deletions

diff --git a/srcs/juloo.keyboard2/KeyEventHandler.java b/srcs/juloo.keyboard2/KeyEventHandler.java
index 36f6819..97a6cd0 100644
--- a/srcs/juloo.keyboard2/KeyEventHandler.java
+++ b/srcs/juloo.keyboard2/KeyEventHandler.java
@@ -3,6 +3,8 @@ package juloo.keyboard2;
 import android.os.Looper;
 import android.view.KeyEvent;
 import android.view.inputmethod.EditorInfo;
+import android.view.inputmethod.ExtractedText;
+import android.view.inputmethod.ExtractedTextRequest;
 import android.view.inputmethod.InputConnection;
 
 class KeyEventHandler implements Config.IKeyEventHandler
@@ -39,33 +41,9 @@ class KeyEventHandler implements Config.IKeyEventHandler
       case Char: send_text(String.valueOf(key.getChar())); break;
       case String: send_text(key.getString()); break;
       case Event: _recv.handle_event_key(key.getEvent()); break;
-      case Keyevent:
-        handleKeyUpWithModifier(key.getKeyevent(), mods);
-        break;
-      case Modifier:
-        break;
-      case Editing:
-        send_context_menu_action(action_of_editing_key(key.getEditing()));
-        break;
-    }
-  }
-
-  static int action_of_editing_key(KeyValue.Editing e)
-  {
-    switch (e)
-    {
-      case COPY: return android.R.id.copy;
-      case PASTE: return android.R.id.paste;
-      case CUT: return android.R.id.cut;
-      case SELECT_ALL: return android.R.id.selectAll;
-      case SHARE: return android.R.id.shareText;
-      case PASTE_PLAIN: return android.R.id.pasteAsPlainText;
-      case UNDO: return android.R.id.undo;
-      case REDO: return android.R.id.redo;
-      case REPLACE: return android.R.id.replaceText;
-      case ASSIST: return android.R.id.textAssist;
-      case AUTOFILL: return android.R.id.autofill;
-      default: return -1; // sad
+      case Keyevent: send_key_down_up(key.getKeyevent(), mods); break;
+      case Modifier: break;
+      case Editing: handle_editing_key(key.getEditing(), mods); break;
     }
   }
 
@@ -108,7 +86,7 @@ class KeyEventHandler implements Config.IKeyEventHandler
   /*
    * Don't set KeyEvent.FLAG_SOFT_KEYBOARD.
    */
-  void handleKeyUpWithModifier(int keyCode, Pointers.Modifiers mods)
+  void send_key_down_up(int keyCode, Pointers.Modifiers mods)
   {
     int metaState = 0;
     for (int i = 0; i < mods.size(); i++)
@@ -147,6 +125,88 @@ class KeyEventHandler implements Config.IKeyEventHandler
     conn.performContextMenuAction(id);
   }
 
+  void handle_editing_key(KeyValue.Editing ev, Pointers.Modifiers mods)
+  {
+    switch (ev)
+    {
+      case COPY: send_context_menu_action(android.R.id.copy); break;
+      case PASTE: send_context_menu_action(android.R.id.paste); break;
+      case CUT: send_context_menu_action(android.R.id.cut); break;
+      case SELECT_ALL: send_context_menu_action(android.R.id.selectAll); break;
+      case SHARE: send_context_menu_action(android.R.id.shareText); break;
+      case PASTE_PLAIN: send_context_menu_action(android.R.id.pasteAsPlainText); break;
+      case UNDO: send_context_menu_action(android.R.id.undo); break;
+      case REDO: send_context_menu_action(android.R.id.redo); break;
+      case REPLACE: send_context_menu_action(android.R.id.replaceText); break;
+      case ASSIST: send_context_menu_action(android.R.id.textAssist); break;
+      case AUTOFILL: send_context_menu_action(android.R.id.autofill); break;
+      case CURSOR_LEFT: move_cursor(-1, mods); break;
+      case CURSOR_RIGHT: move_cursor(1, mods); break;
+    }
+  }
+
+  static ExtractedTextRequest _move_cursor_req = null;
+
+  /** Query the cursor position. The extracted text is empty. Returns [null] if
+      the editor doesn't support this operation. */
+  ExtractedText get_cursor_pos(InputConnection conn)
+  {
+    if (_move_cursor_req == null)
+    {
+      _move_cursor_req = new ExtractedTextRequest();
+      _move_cursor_req.hintMaxChars = 0;
+    }
+    return conn.getExtractedText(_move_cursor_req, 0);
+  }
+
+  /** Move the cursor right or left, if possible without sending key events.
+      Unlike arrow keys, the selection is not removed even if shift is not on. */
+  void move_cursor(int d, Pointers.Modifiers mods)
+  {
+    InputConnection conn = _recv.getCurrentInputConnection();
+    if (conn == null)
+      return;
+    ExtractedText et = get_cursor_pos(conn);
+    if (et == null) // Editor doesn't support moving the cursor
+    {
+      move_cursor_fallback(d, mods);
+      return;
+    }
+    int sel_start = et.selectionStart;
+    int sel_end = et.selectionEnd;
+    // Continue expanding the selection even if shift is not pressed
+    if (sel_end != sel_start)
+    {
+      sel_end += d;
+      if (sel_end == sel_start) // Avoid making the selection empty
+        sel_end += d;
+    }
+    else
+    {
+      sel_end += d;
+      // Leave 'sel_start' where it is if shift is pressed
+      if (!mods.has(KeyValue.Modifier.SHIFT))
+        sel_start = sel_end;
+    }
+    conn.setSelection(sel_start, sel_end);
+  }
+
+  /** Send arrow keys as a fallback for editors that do not support
+      [getExtractedText] like Termux. */
+  void move_cursor_fallback(int d, Pointers.Modifiers mods)
+  {
+    while (d < 0)
+    {
+      send_key_down_up(KeyEvent.KEYCODE_DPAD_LEFT, mods);
+      d++;
+    }
+    while (d > 0)
+    {
+      send_key_down_up(KeyEvent.KEYCODE_DPAD_RIGHT, mods);
+      d--;
+    }
+  }
+
   public static interface IReceiver
   {
     public void handle_event_key(KeyValue.Event ev);