Normalization of Korean characters

This changes how some characters are sent to the editor.
Characters specified in 'should_normalize_char' are not committed
immediately to the editor but instead added to the composing text.

The composing text is NFCKC-normalized. Resulting characters that are
not in 'should_normalize_char' committed, the rest is the composing
text.

Typing a character not specified here do not change: commitText is used
immediately.

srcs/juloo.keyboard2/Autonormalization.java

@@ -0,0 +1,104 @@
+package juloo.keyboard2;
+
+import android.view.inputmethod.EditorInfo;
+import android.icu.text.Normalizer2;
+import android.view.inputmethod.InputConnection;
+
+/** Compose the characters specified in [should_normalize_char()] using unicode
+    normalization. The composing region is used to mark text where
+    normalization could happen if more characters are typed. */
+public final class Autonormalization
+{
+  /** Composing text waiting for more combinations. */
+  StringBuilder _c = new StringBuilder();
+  InputConnection _ic = null;
+  Normalizer2 _normalizer_cached = null;
+
+  public Autonormalization() {}
+
+  public void started(EditorInfo info, InputConnection ic)
+  {
+    _ic = ic;
+    _c.setLength(0);
+  }
+
+  /** If the characters could combine with a following character, update the
+      composing text and return [true]. If the typed chars can't combine, flush
+      the composing text and return [false], without committing the text. */
+  public boolean typed(CharSequence s)
+  {
+    if (_ic == null || s.length() == 0)
+      return false;
+    if (should_normalize_char(s.charAt(0)))
+    {
+      type_normalized(s);
+      return true;
+    }
+    flush();
+    return false;
+  }
+
+  /** Handle key events, might flush the composing text. Do not call [typed]. */
+  public void key_up(KeyValue kv)
+  {
+    switch (kv.getKind())
+    {
+      // [typed] will be called later
+      case Char:
+      case String: break;
+      // Do not change the composing text for these keys
+      case Modifier:
+      case Compose_pending: break;
+      // The other keys flush the composing text
+      case Event:
+      case Keyevent:
+      case Editing:
+        flush();
+        break;
+    }
+  }
+
+  /** If [typed()] has been called before, [flush()] must be called before
+      sending any other command to the [InputConnection]. */
+  void flush()
+  {
+    if (_ic == null)
+      return;
+    _c.setLength(0);
+    _ic.finishComposingText();
+  }
+
+  Normalizer2 normalizer()
+  {
+    if (_normalizer_cached == null)
+      _normalizer_cached = Normalizer2.getNFKCInstance();
+    return _normalizer_cached;
+  }
+
+  void type_normalized(CharSequence s)
+  {
+    Normalizer2 norm = normalizer();
+    norm.normalizeSecondAndAppend(_c, s);
+    /* Only keep the string of normalizable character at the end of [_c].
+       Commit the rest. */
+    int i = _c.length() - 1;
+    while (i > 0 && should_normalize_char(_c.charAt(i)))
+      i--;
+    if (i > 0)
+    {
+      _ic.commitText(_c.subSequence(0, i), 1);
+      _c.delete(0, i);
+    }
+    _ic.setComposingText(_c, 1);
+  }
+
+  /** Characters for which autonormalization will happen. */
+  boolean should_normalize_char(char c)
+  {
+    return (c >= '\u1100' && c <= '\u11FF') // Hangul Jamo
+      || (c >= '\u3130' && c <= '\u318F') // Hangul Compatibility Jamo
+      || (c >= '\uA960' && c <= '\uA97F') // Hangul Jamo Extended-A
+      || (c >= '\uD7B0' && c <= '\uD7FF') // Hangul Jamo Extended-B
+      ;
+  }
+}

srcs/juloo.keyboard2/KeyEventHandler.java

@@ -14,6 +14,7 @@ public final class KeyEventHandler implements Config.IKeyEventHandler
 {
   IReceiver _recv;
   Autocapitalisation _autocap;
+  Autonormalization _autonorm;
   /** State of the system modifiers. It is updated whether a modifier is down
       or up and a corresponding key event is sent. */
   Pointers.Modifiers _mods;
@@ -30,13 +31,16 @@ public final class KeyEventHandler implements Config.IKeyEventHandler
     _recv = recv;
     _autocap = new Autocapitalisation(looper,
         this.new Autocapitalisation_callback());
+    _autonorm = new Autonormalization();
     _mods = Pointers.Modifiers.EMPTY;
   }
 
   /** Editing just started. */
   public void started(EditorInfo info)
   {
-    _autocap.started(info, _recv.getCurrentInputConnection());
+    InputConnection ic = _recv.getCurrentInputConnection();
+    _autocap.started(info, ic);
+    _autonorm.started(info, ic);
     // Workaround a bug in Acode, which answers to [getExtractedText] but do
     // not react to [setSelection] while returning [true].
     // Note: Using & to workaround a bug in Acode, which sets several
@@ -86,6 +90,8 @@ public final class KeyEventHandler implements Config.IKeyEventHandler
       return;
     Pointers.Modifiers old_mods = _mods;
     update_meta_state(mods);
+    // Handles sending text
+    _autonorm.key_up(key);
     switch (key.getKind())
     {
       case Char: send_text(String.valueOf(key.getChar())); break;
@@ -192,6 +198,7 @@ public final class KeyEventHandler implements Config.IKeyEventHandler
     InputConnection conn = _recv.getCurrentInputConnection();
     if (conn == null)
       return;
+    if (!_autonorm.typed(text))
       conn.commitText(text, 1);
     _autocap.typed(text);
   }