Add a compatibility library for newly added methods in L

This CL adds an compatibility library for
InputConnection#requestCursorAnchorInfo method that is supposed to
be available in L and later.

BUG: 16382260
Change-Id: I68be0c56b9fd929546e8706ccece938ae4f33339

java/src/com/android/inputmethod/compat/InputConnectionCompatUtils.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2014 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.compat;
+
+import android.view.inputmethod.InputConnection;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Method;
+
+public final class InputConnectionCompatUtils {
+    // Note that CursorAnchorInfoRequest is supposed to be available in API level 21 and later.
+    private static Class<?> getCursorAnchorInfoRequestClass() {
+        try {
+            return Class.forName("android.view.inputmethod.CursorAnchorInfoRequest");
+        } catch (ClassNotFoundException e) {
+            return null;
+        }
+    }
+
+    private static final Class<?> TYPE_CursorAnchorInfoRequest;
+    private static final Constructor<?> CONSTRUCTOR_CursorAnchorInfoRequest;
+    private static final Method METHOD_requestCursorAnchorInfo;
+    static {
+        TYPE_CursorAnchorInfoRequest = getCursorAnchorInfoRequestClass();
+        CONSTRUCTOR_CursorAnchorInfoRequest = CompatUtils.getConstructor(
+                TYPE_CursorAnchorInfoRequest, int.class, int.class);
+        METHOD_requestCursorAnchorInfo = CompatUtils.getMethod(InputConnection.class,
+                "requestCursorAnchorInfo", TYPE_CursorAnchorInfoRequest);
+    }
+
+    public static boolean isRequestCursorAnchorInfoAvailable() {
+        return METHOD_requestCursorAnchorInfo != null &&
+                CONSTRUCTOR_CursorAnchorInfoRequest != null;
+    }
+
+    /**
+     * A local copy of CursorAnchorInfoRequest.RESULT_NOT_HANDLED until the SDK becomes publicly
+     * available.
+     */
+    private final static int CURSOR_ANCHOR_INFO_REQUEST_RESULT_NOT_HANDLED = 0;
+
+    public static int requestCursorAnchorInfo(final InputConnection inputConnection,
+            final int type, final int flags) {
+        if (!isRequestCursorAnchorInfoAvailable()) {
+             return CURSOR_ANCHOR_INFO_REQUEST_RESULT_NOT_HANDLED;
+        }
+        final Object requestObject = CompatUtils.newInstance(
+                CONSTRUCTOR_CursorAnchorInfoRequest, type, flags);
+        if (requestObject == null) {
+            return CURSOR_ANCHOR_INFO_REQUEST_RESULT_NOT_HANDLED;
+        }
+        return (Integer) CompatUtils.invoke(inputConnection,
+                CURSOR_ANCHOR_INFO_REQUEST_RESULT_NOT_HANDLED /* defaultValue */,
+                METHOD_requestCursorAnchorInfo, requestObject);
+    }
+}