Initial implementation for dead keys (B3)

Bug: 5037589
Change-Id: I9e1ff92df7d0c58eb7a0f33603adebc9efb86585

1 files changed, 61 insertions, 0 deletions

diff --git a/java/src/com/android/inputmethod/event/DeadKeyCombiner.java b/java/src/com/android/inputmethod/event/DeadKeyCombiner.java
new file mode 100644
index 000000000..52987d571
--- /dev/null
+++ b/java/src/com/android/inputmethod/event/DeadKeyCombiner.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.inputmethod.event;
+
+import android.text.TextUtils;
+import android.view.KeyCharacterMap;
+
+import com.android.inputmethod.latin.Constants;
+
+/**
+ * A combiner that handles dead keys.
+ */
+public class DeadKeyCombiner implements Combiner {
+    final StringBuilder mDeadSequence = new StringBuilder();
+
+    @Override
+    public Event combine(final Event event) {
+        if (null == event) return null; // Just in case some combiner is broken
+        if (TextUtils.isEmpty(mDeadSequence)) {
+            if (event.isDead()) {
+                mDeadSequence.appendCodePoint(event.mCodePoint);
+            }
+            return event;
+        } else {
+            // TODO: Allow combining for several dead chars rather than only the first one.
+            // The framework doesn't know how to do this now.
+            final int deadCodePoint = mDeadSequence.codePointAt(0);
+            mDeadSequence.setLength(0);
+            final int resultingCodePoint =
+                    KeyCharacterMap.getDeadChar(deadCodePoint, event.mCodePoint);
+            if (0 == resultingCodePoint) {
+                // We can't combine both characters. We need to commit the dead key as a committable
+                // character, and the next char too unless it's a space (because as a special case,
+                // dead key + space should result in only the dead key being committed - that's
+                // how dead keys work).
+                // If the event is a space, we should commit the dead char alone, but if it's
+                // not, we need to commit both.
+                return Event.createCommittableEvent(deadCodePoint,
+                        Constants.CODE_SPACE == event.mCodePoint ? null : event /* next */);
+            } else {
+                // We could combine the characters.
+                return Event.createCommittableEvent(resultingCodePoint, null /* next */);
+            }
+        }
+    }
+
+}