Add ViewTreeObserverWrapper

/*

 * Copyright (C) 2020 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.systemui.shared.system;

import android.annotation.Nullable;

import android.graphics.Rect;

import android.graphics.Region;

import android.view.ViewTreeObserver;

import android.view.ViewTreeObserver.OnComputeInternalInsetsListener;

import java.util.HashMap;

public class ViewTreeObserverWrapper {

    private static final HashMap<OnComputeInsetsListener, OnComputeInternalInsetsListener>

            sOnComputeInsetsListenerMap = new HashMap<>();

    /**

     * Register a callback to be invoked when the invoked when it is time to

     * compute the window's insets.

     *

     * @param listener The callback to add

     * @throws IllegalStateException If {@link ViewTreeObserver#isAlive()} returns false

     */

    public static void addOnComputeInsetsListener(

            ViewTreeObserver observer, OnComputeInsetsListener listener) {

        final OnComputeInternalInsetsListener internalListener = internalInOutInfo -> {

            final InsetsInfo inOutInfo = new InsetsInfo();

            inOutInfo.contentInsets.set(internalInOutInfo.contentInsets);

            inOutInfo.visibleInsets.set(internalInOutInfo.visibleInsets);

            inOutInfo.touchableRegion.set(internalInOutInfo.touchableRegion);

            listener.onComputeInsets(inOutInfo);

            internalInOutInfo.contentInsets.set(inOutInfo.contentInsets);

            internalInOutInfo.visibleInsets.set(inOutInfo.visibleInsets);

            internalInOutInfo.touchableRegion.set(inOutInfo.touchableRegion);

            internalInOutInfo.setTouchableInsets(inOutInfo.mTouchableInsets);

        };

        sOnComputeInsetsListenerMap.put(listener, internalListener);

        observer.addOnComputeInternalInsetsListener(internalListener);

    }

    /**

     * Remove a previously installed insets computation callback

     *

     * @param victim The callback to remove

     * @throws IllegalStateException If {@link ViewTreeObserver#isAlive()} returns false

     * @see #addOnComputeInsetsListener(ViewTreeObserver, OnComputeInsetsListener)

     */

    public void removeOnComputeInsetsListener(

            ViewTreeObserver observer, OnComputeInsetsListener victim) {

        final OnComputeInternalInsetsListener listener = sOnComputeInsetsListenerMap.get(victim);

        if (listener != null) {

            observer.removeOnComputeInternalInsetsListener(listener);

        }

    }

    /**

     * Interface definition for a callback to be invoked when layout has

     * completed and the client can compute its interior insets.

     */

    public interface OnComputeInsetsListener {

        /**

         * Callback method to be invoked when layout has completed and the

         * client can compute its interior insets.

         *

         * @param inoutInfo Should be filled in by the implementation with

         * the information about the insets of the window.  This is called

         * with whatever values the previous OnComputeInsetsListener

         * returned, if there are multiple such listeners in the window.

         */

        void onComputeInsets(InsetsInfo inoutInfo);

    }

    /**

     * Parameters used with OnComputeInsetsListener.

     */

    public final static class InsetsInfo {

        /**

         * Offsets from the frame of the window at which the content of

         * windows behind it should be placed.

         */

        public final Rect contentInsets = new Rect();

        /**

         * Offsets from the frame of the window at which windows behind it

         * are visible.

         */

        public final Rect visibleInsets = new Rect();

        /**

         * Touchable region defined relative to the origin of the frame of the window.

         * Only used when {@link #setTouchableInsets(int)} is called with

         * the option {@link #TOUCHABLE_INSETS_REGION}.

         */

        public final Region touchableRegion = new Region();

        /**

         * Option for {@link #setTouchableInsets(int)}: the entire window frame

         * can be touched.

         */

        public static final int TOUCHABLE_INSETS_FRAME =

                ViewTreeObserver.InternalInsetsInfo.TOUCHABLE_INSETS_FRAME;

        /**

         * Option for {@link #setTouchableInsets(int)}: the area inside of

         * the content insets can be touched.

         */

        public static final int TOUCHABLE_INSETS_CONTENT =

                ViewTreeObserver.InternalInsetsInfo.TOUCHABLE_INSETS_CONTENT;

        /**

         * Option for {@link #setTouchableInsets(int)}: the area inside of

         * the visible insets can be touched.

         */

        public static final int TOUCHABLE_INSETS_VISIBLE =

                ViewTreeObserver.InternalInsetsInfo.TOUCHABLE_INSETS_VISIBLE;

        /**

         * Option for {@link #setTouchableInsets(int)}: the area inside of

         * the provided touchable region in {@link #touchableRegion} can be touched.

         */

        public static final int TOUCHABLE_INSETS_REGION =

                ViewTreeObserver.InternalInsetsInfo.TOUCHABLE_INSETS_REGION;

        /**

         * Set which parts of the window can be touched: either

         * {@link #TOUCHABLE_INSETS_FRAME}, {@link #TOUCHABLE_INSETS_CONTENT},

         * {@link #TOUCHABLE_INSETS_VISIBLE}, or {@link #TOUCHABLE_INSETS_REGION}.

         */

        public void setTouchableInsets(int val) {

            mTouchableInsets = val;

        }

        int mTouchableInsets;

        @Override

        public int hashCode() {

            int result = contentInsets.hashCode();

            result = 31 * result + visibleInsets.hashCode();

            result = 31 * result + touchableRegion.hashCode();

            result = 31 * result + mTouchableInsets;

            return result;

        }

        @Override

        public boolean equals(@Nullable Object o) {

            if (this == o) return true;

            if (o == null || getClass() != o.getClass()) return false;

            final InsetsInfo other = (InsetsInfo) o;

            return mTouchableInsets == other.mTouchableInsets &&

                    contentInsets.equals(other.contentInsets) &&

                    visibleInsets.equals(other.visibleInsets) &&

                    touchableRegion.equals(other.touchableRegion);

        }

    }

}