src/com/android/documentsui/dirlist/AccessibilityEventRouter.java

/*
 * Copyright (C) 2017 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.documentsui.dirlist;

import android.os.Bundle;
import android.view.View;
import android.view.accessibility.AccessibilityNodeInfo;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

import java.util.function.Function;

/**
 * Custom Accessibility Delegate for item views in RecyclerViews to route click events to
 * proper handlers, and to surface selection state to a11y events.
 * <p>
 * The majority of event handling isdone using TouchDetector instead of View.OnCLickListener, which
 * most a11y services use to understand whether a particular view is clickable or not. Thus, we need
 * to use a custom accessibility delegate to manually add ACTION_CLICK to clickable child views'
 * accessibility node, and then correctly route these clicks done by a11y services to responsible
 * click callbacks.
 * <p>
 * DocumentsUI uses {@link View#setActivated(boolean)} instead of {@link View#setSelected(boolean)}
 * for marking a view as selected. We will surface that selection state to a11y services in this
 * class.
 */
public class AccessibilityEventRouter extends View.AccessibilityDelegate {

    private final Function<View, Boolean> mClickCallback;
    private final Function<View, Boolean> mLongClickCallback;

    public AccessibilityEventRouter(
            @NonNull Function<View, Boolean> clickCallback,
            @Nullable Function<View, Boolean> longClickCallback) {
        super();
        mClickCallback = clickCallback;
        mLongClickCallback = longClickCallback;
    }

    @Override
    public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfo info) {
        addAction(info);
        info.setSelected(host.isActivated());
    }

    @Override
    public boolean performAccessibilityAction(View host, int action, Bundle args) {
        // We are only handling click events; route all other to default implementation
        if (action == AccessibilityNodeInfo.ACTION_CLICK) {
            return mClickCallback.apply(host);
        } else if (action == AccessibilityNodeInfo.ACTION_LONG_CLICK
                && mLongClickCallback != null) {
            return mLongClickCallback.apply(host);
        }
        return super.performAccessibilityAction(host, action, args);
    }

    private void addAction(AccessibilityNodeInfo info) {
        info.addAction(AccessibilityNodeInfo.ACTION_CLICK);
        if (mLongClickCallback != null) {
            info.addAction(AccessibilityNodeInfo.ACTION_LONG_CLICK);
        }
    }
}