public class

RecyclerViewAccessibilityDelegate

extends AccessibilityDelegateCompat

 java.lang.Object

androidx.core.view.AccessibilityDelegateCompat

↳androidx.recyclerview.widget.RecyclerViewAccessibilityDelegate

Subclasses:

PreferenceRecyclerViewAccessibilityDelegate

Gradle dependencies

compile group: 'androidx.recyclerview', name: 'recyclerview', version: '1.3.0-alpha02'

  • groupId: androidx.recyclerview
  • artifactId: recyclerview
  • version: 1.3.0-alpha02

Artifact androidx.recyclerview:recyclerview:1.3.0-alpha02 it located at Google repository (https://maven.google.com/)

Androidx artifact mapping:

androidx.recyclerview:recyclerview com.android.support:recyclerview-v7

Androidx class mapping:

androidx.recyclerview.widget.RecyclerViewAccessibilityDelegate android.support.v7.widget.RecyclerViewAccessibilityDelegate

Overview

The AccessibilityDelegate used by RecyclerView.

This class handles basic accessibility actions and delegates them to LayoutManager.

Summary

Constructors
publicRecyclerViewAccessibilityDelegate(RecyclerView recyclerView)

Methods
public AccessibilityDelegateCompatgetItemDelegate()

Gets the AccessibilityDelegate for an individual item in the RecyclerView.

public voidonInitializeAccessibilityEvent(View host, AccessibilityEvent event)

Initializes an with information about the the host View which is the event source.

public voidonInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info)

Initializes an AccessibilityNodeInfoCompat with information about the host view.

public booleanperformAccessibilityAction(View host, int action, Bundle args)

Performs the specified accessibility action on the view.

from AccessibilityDelegateCompatdispatchPopulateAccessibilityEvent, getAccessibilityNodeProvider, onPopulateAccessibilityEvent, onRequestSendAccessibilityEvent, sendAccessibilityEvent, sendAccessibilityEventUnchecked
from java.lang.Objectclone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructors

public RecyclerViewAccessibilityDelegate(RecyclerView recyclerView)

Methods

public boolean performAccessibilityAction(View host, int action, Bundle args)

Performs the specified accessibility action on the view. For possible accessibility actions look at AccessibilityNodeInfoCompat.

The default implementation behaves as View#performAccessibilityAction(int, Bundle) for the case of no accessibility delegate been set.

Parameters:

host: View on which to perform the action.
action: The action to perform.
args: Optional action arguments.

Returns:

Whether the action was performed.

See also: View#performAccessibilityAction(int, Bundle)

public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info)

Initializes an AccessibilityNodeInfoCompat with information about the host view.

The default implementation behaves as ViewCompat#onInitializeAccessibilityNodeInfo(View, AccessibilityNodeInfoCompat) for the case of no accessibility delegate been set.

Parameters:

host: The View hosting the delegate.
info: The instance to initialize.

See also: ViewCompat#onInitializeAccessibilityNodeInfo(View, AccessibilityNodeInfoCompat)

public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event)

Initializes an with information about the the host View which is the event source.

The default implementation behaves as ViewCompat#onInitalizeAccessibilityEvent(View v, AccessibilityEvent event) for the case of no accessibility delegate been set.

Parameters:

host: The View hosting the delegate.
event: The event to initialize.

See also: ViewCompat#onInitializeAccessibilityEvent(View, AccessibilityEvent)

public AccessibilityDelegateCompat getItemDelegate()

Gets the AccessibilityDelegate for an individual item in the RecyclerView. A basic item delegate is provided by default, but you can override this method to provide a custom per-item delegate. For now, returning an AccessibilityDelegateCompat as opposed to an ItemDelegate will prevent use of the ViewCompat accessibility API on item views.

Source

/*
 * Copyright 2018 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 androidx.recyclerview.widget;

import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.accessibility.AccessibilityEvent;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.core.view.AccessibilityDelegateCompat;
import androidx.core.view.ViewCompat;
import androidx.core.view.accessibility.AccessibilityNodeInfoCompat;
import androidx.core.view.accessibility.AccessibilityNodeProviderCompat;

import java.util.Map;
import java.util.WeakHashMap;

/**
 * The AccessibilityDelegate used by RecyclerView.
 * <p>
 * This class handles basic accessibility actions and delegates them to LayoutManager.
 */
public class RecyclerViewAccessibilityDelegate extends AccessibilityDelegateCompat {
    final RecyclerView mRecyclerView;
    private final ItemDelegate mItemDelegate;


    public RecyclerViewAccessibilityDelegate(@NonNull RecyclerView recyclerView) {
        mRecyclerView = recyclerView;
        AccessibilityDelegateCompat itemDelegate = getItemDelegate();
        if (itemDelegate != null && itemDelegate instanceof ItemDelegate) {
            mItemDelegate = (ItemDelegate) itemDelegate;
        } else {
            mItemDelegate = new ItemDelegate(this);
        }
    }

    boolean shouldIgnore() {
        return mRecyclerView.hasPendingAdapterUpdates();
    }

    @Override
    public boolean performAccessibilityAction(View host, int action, Bundle args) {
        if (super.performAccessibilityAction(host, action, args)) {
            return true;
        }
        if (!shouldIgnore() && mRecyclerView.getLayoutManager() != null) {
            return mRecyclerView.getLayoutManager().performAccessibilityAction(action, args);
        }

        return false;
    }

    @Override
    public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) {
        super.onInitializeAccessibilityNodeInfo(host, info);
        if (!shouldIgnore() && mRecyclerView.getLayoutManager() != null) {
            mRecyclerView.getLayoutManager().onInitializeAccessibilityNodeInfo(info);
        }
    }

    @Override
    public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event) {
        super.onInitializeAccessibilityEvent(host, event);
        if (host instanceof RecyclerView && !shouldIgnore()) {
            RecyclerView rv = (RecyclerView) host;
            if (rv.getLayoutManager() != null) {
                rv.getLayoutManager().onInitializeAccessibilityEvent(event);
            }
        }
    }

    /**
     * Gets the AccessibilityDelegate for an individual item in the RecyclerView.
     * A basic item delegate is provided by default, but you can override this
     * method to provide a custom per-item delegate.
     * For now, returning an {@code AccessibilityDelegateCompat} as opposed to an
     * {@code ItemDelegate} will prevent use of the {@code ViewCompat} accessibility API on
     * item views.
     */
    @NonNull
    public AccessibilityDelegateCompat getItemDelegate() {
        return mItemDelegate;
    }

    /**
     * The default implementation of accessibility delegate for the individual items of the
     * RecyclerView.
     * <p>
     * If you are overriding {@code RecyclerViewAccessibilityDelegate#getItemDelegate()} but still
     * want to keep some default behavior, you can create an instance of this class and delegate to
     * the parent as necessary.
     */
    public static class ItemDelegate extends AccessibilityDelegateCompat {
        final RecyclerViewAccessibilityDelegate mRecyclerViewDelegate;
        private Map<View, AccessibilityDelegateCompat> mOriginalItemDelegates = new WeakHashMap<>();

        /**
         * Creates an item delegate for the given {@code RecyclerViewAccessibilityDelegate}.
         *
         * @param recyclerViewDelegate The parent RecyclerView's accessibility delegate.
         */
        public ItemDelegate(@NonNull RecyclerViewAccessibilityDelegate recyclerViewDelegate) {
            mRecyclerViewDelegate = recyclerViewDelegate;
        }

        /**
         * Saves a reference to the original delegate of the itemView so that it's behavior can be
         * combined with the ItemDelegate's behavior.
         */
        void saveOriginalDelegate(View itemView) {
            AccessibilityDelegateCompat delegate = ViewCompat.getAccessibilityDelegate(itemView);
            if (delegate != null && delegate != this) {
                mOriginalItemDelegates.put(itemView, delegate);
            }
        }

        /**
         * @return The delegate associated with itemView before the view was bound.
         */
        AccessibilityDelegateCompat getAndRemoveOriginalDelegateForItem(View itemView) {
            return mOriginalItemDelegates.remove(itemView);
        }

        @Override
        public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) {
            if (!mRecyclerViewDelegate.shouldIgnore()
                    && mRecyclerViewDelegate.mRecyclerView.getLayoutManager() != null) {
                mRecyclerViewDelegate.mRecyclerView.getLayoutManager()
                        .onInitializeAccessibilityNodeInfoForItem(host, info);
                AccessibilityDelegateCompat originalDelegate = mOriginalItemDelegates.get(host);
                if (originalDelegate != null) {
                    originalDelegate.onInitializeAccessibilityNodeInfo(host, info);
                } else {
                    super.onInitializeAccessibilityNodeInfo(host, info);
                }
            } else {
                super.onInitializeAccessibilityNodeInfo(host, info);
            }
        }

        @Override
        public boolean performAccessibilityAction(View host, int action, Bundle args) {
            if (!mRecyclerViewDelegate.shouldIgnore()
                    && mRecyclerViewDelegate.mRecyclerView.getLayoutManager() != null) {
                AccessibilityDelegateCompat originalDelegate = mOriginalItemDelegates.get(host);
                if (originalDelegate != null) {
                    if (originalDelegate.performAccessibilityAction(host, action, args)) {
                        return true;
                    }
                } else if (super.performAccessibilityAction(host, action, args)) {
                    return true;
                }
                return mRecyclerViewDelegate.mRecyclerView.getLayoutManager()
                        .performAccessibilityActionForItem(host, action, args);
            } else {
                return super.performAccessibilityAction(host, action, args);
            }
        }

        @Override
        public void sendAccessibilityEvent(@NonNull View host, int eventType) {
            AccessibilityDelegateCompat originalDelegate = mOriginalItemDelegates.get(host);
            if (originalDelegate != null) {
                originalDelegate.sendAccessibilityEvent(host, eventType);
            } else {
                super.sendAccessibilityEvent(host, eventType);
            }
        }

        @Override
        public void sendAccessibilityEventUnchecked(@NonNull View host,
                @NonNull AccessibilityEvent event) {
            AccessibilityDelegateCompat originalDelegate = mOriginalItemDelegates.get(host);
            if (originalDelegate != null) {
                originalDelegate.sendAccessibilityEventUnchecked(host, event);
            } else {
                super.sendAccessibilityEventUnchecked(host, event);
            }
        }

        @Override
        public boolean dispatchPopulateAccessibilityEvent(@NonNull View host,
                @NonNull AccessibilityEvent event) {
            AccessibilityDelegateCompat originalDelegate = mOriginalItemDelegates.get(host);
            if (originalDelegate != null) {
                return originalDelegate.dispatchPopulateAccessibilityEvent(host, event);
            } else {
                return super.dispatchPopulateAccessibilityEvent(host, event);
            }
        }

        @Override
        public void onPopulateAccessibilityEvent(@NonNull View host,
                @NonNull AccessibilityEvent event) {
            AccessibilityDelegateCompat originalDelegate = mOriginalItemDelegates.get(host);
            if (originalDelegate != null) {
                originalDelegate.onPopulateAccessibilityEvent(host, event);
            } else {
                super.onPopulateAccessibilityEvent(host, event);
            }
        }

        @Override
        public void onInitializeAccessibilityEvent(@NonNull View host,
                @NonNull AccessibilityEvent event) {
            AccessibilityDelegateCompat originalDelegate = mOriginalItemDelegates.get(host);
            if (originalDelegate != null) {
                originalDelegate.onInitializeAccessibilityEvent(host, event);
            } else {
                super.onInitializeAccessibilityEvent(host, event);
            }
        }

        @Override
        public boolean onRequestSendAccessibilityEvent(@NonNull ViewGroup host,
                @NonNull View child, @NonNull AccessibilityEvent event) {
            AccessibilityDelegateCompat originalDelegate = mOriginalItemDelegates.get(host);
            if (originalDelegate != null) {
                return originalDelegate.onRequestSendAccessibilityEvent(host, child, event);
            } else {
                return super.onRequestSendAccessibilityEvent(host, child, event);
            }
        }

        @Override
        @Nullable
        public AccessibilityNodeProviderCompat getAccessibilityNodeProvider(@NonNull View host) {
            AccessibilityDelegateCompat originalDelegate = mOriginalItemDelegates.get(host);
            if (originalDelegate != null) {
                return originalDelegate.getAccessibilityNodeProvider(host);
            } else {
                return super.getAccessibilityNodeProvider(host);
            }
        }
    }
}