Add CursorAnchorInfoCompatWrapper for KitKat and older platforms

/*

 * 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.graphics.Matrix;

import android.graphics.RectF;

import com.android.inputmethod.annotations.UsedForTesting;

import java.lang.reflect.Method;

@UsedForTesting

public final class CursorAnchorInfoCompatWrapper {

    // Note that CursorAnchorInfo has been introduced in API level XX (Build.VERSION_CODE.LXX).

    private static Class<?> getCursorAnchorInfoClass() {

        try {

            return Class.forName("android.view.inputmethod.CursorAnchorInfo");

        } catch (ClassNotFoundException e) {

            return null;

        }

    }

    private static final Class<?> CLASS;

    private static final Method METHOD_GET_CHARACTER_RECT;

    private static final Method METHOD_GET_CHARACTER_RECT_FLAGS;

    private static final Method METHOD_GET_COMPOSING_TEXT;

    private static final Method METHOD_GET_COMPOSING_TEXT_START;

    private static final Method METHOD_GET_MATRIX;

    static {

        CLASS = getCursorAnchorInfoClass();

        METHOD_GET_CHARACTER_RECT = CompatUtils.getMethod(CLASS, "getCharacterRect", int.class);

        METHOD_GET_CHARACTER_RECT_FLAGS = CompatUtils.getMethod(CLASS, "getCharacterRectFlags",

                int.class);

        METHOD_GET_COMPOSING_TEXT = CompatUtils.getMethod(CLASS, "getComposingText");

        METHOD_GET_COMPOSING_TEXT_START = CompatUtils.getMethod(CLASS, "getComposingTextStart");

        METHOD_GET_MATRIX = CompatUtils.getMethod(CLASS, "getMatrix");

    }

    @UsedForTesting

    public static boolean isAvailable() {

        return CLASS != null;

    }

    public static final int CHARACTER_RECT_TYPE_MASK = 0x0f;

    /**

     * Type for {@link #CHARACTER_RECT_TYPE_MASK}: the editor did not specify any type of this

     * character. Editor authors should not use this flag.

     */

    public static final int CHARACTER_RECT_TYPE_UNSPECIFIED = 0;

    /**

     * Type for {@link #CHARACTER_RECT_TYPE_MASK}: the character is entirely visible.

     */

    public static final int CHARACTER_RECT_TYPE_FULLY_VISIBLE = 1;

    /**

     * Type for {@link #CHARACTER_RECT_TYPE_MASK}: some area of the character is invisible.

     */

    public static final int CHARACTER_RECT_TYPE_PARTIALLY_VISIBLE = 2;

    /**

     * Type for {@link #CHARACTER_RECT_TYPE_MASK}: the character is entirely invisible.

     */

    public static final int CHARACTER_RECT_TYPE_INVISIBLE = 3;

    /**

     * Type for {@link #CHARACTER_RECT_TYPE_MASK}: the editor gave up to calculate the rectangle

     * for this character. Input method authors should ignore the returned rectangle.

     */

    public static final int CHARACTER_RECT_TYPE_NOT_FEASIBLE = 4;

    private Object mInstance;

    private CursorAnchorInfoCompatWrapper(final Object instance) {

        mInstance = instance;

    }

    @UsedForTesting

    public static CursorAnchorInfoCompatWrapper fromObject(final Object instance) {

        if (!isAvailable()) {

            return new CursorAnchorInfoCompatWrapper(null);

        }

        return new CursorAnchorInfoCompatWrapper(instance);

    }

    private static final class FakeHolder {

        static CursorAnchorInfoCompatWrapper sInstance = new CursorAnchorInfoCompatWrapper(null);

    }

    @UsedForTesting

    public static CursorAnchorInfoCompatWrapper getFake() {

        return FakeHolder.sInstance;

    }

    public CharSequence getComposingText() {

        return (CharSequence) CompatUtils.invoke(mInstance, null, METHOD_GET_COMPOSING_TEXT);

    }

    private static int COMPOSING_TEXT_START_DEFAULT = -1;

    public int getComposingTextStart() {

        if (mInstance == null || METHOD_GET_COMPOSING_TEXT_START == null) {

            return COMPOSING_TEXT_START_DEFAULT;

        }

        return (int) CompatUtils.invoke(mInstance, null, METHOD_GET_COMPOSING_TEXT_START);

    }

    public Matrix getMatrix() {

        return (Matrix) CompatUtils.invoke(mInstance, null, METHOD_GET_MATRIX);

    }

    public RectF getCharacterRect(final int index) {

        return (RectF) CompatUtils.invoke(mInstance, null, METHOD_GET_CHARACTER_RECT, index);

    }

    public int getCharacterRectFlags(final int index) {

        if (mInstance == null || METHOD_GET_CHARACTER_RECT_FLAGS == null) {

            return CHARACTER_RECT_TYPE_UNSPECIFIED;

        }

        return (int) CompatUtils.invoke(mInstance, null, METHOD_GET_CHARACTER_RECT_FLAGS, index);

    }

}