Java tutorial
/* * Copyright (C) 2011 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 android.support.v4.view; import android.os.Build; import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat; import android.view.View; import android.view.ViewGroup; import android.view.accessibility.AccessibilityEvent; /** * Helper for accessing {@link View.AccessibilityDelegate} introduced after * API level 4 in a backwards compatible fashion. */ public class AccessibilityDelegateCompat { static interface AccessibilityDelegateImpl { public Object newAccessiblityDelegateDefaultImpl(); public Object newAccessiblityDelegateBridge(AccessibilityDelegateCompat listener); public boolean dispatchPopulateAccessibilityEvent(Object delegate, View host, AccessibilityEvent event); public void onInitializeAccessibilityEvent(Object delegate, View host, AccessibilityEvent event); public void onInitializeAccessibilityNodeInfo(Object delegate, View host, AccessibilityNodeInfoCompat info); public void onPopulateAccessibilityEvent(Object delegate, View host, AccessibilityEvent event); public boolean onRequestSendAccessibilityEvent(Object delegate, ViewGroup host, View child, AccessibilityEvent event); public void sendAccessibilityEvent(Object delegate, View host, int eventType); public void sendAccessibilityEventUnchecked(Object delegate, View host, AccessibilityEvent event); } static class AccessibilityDelegateStubImpl implements AccessibilityDelegateImpl { public Object newAccessiblityDelegateDefaultImpl() { return null; } public Object newAccessiblityDelegateBridge(AccessibilityDelegateCompat listener) { return null; } public boolean dispatchPopulateAccessibilityEvent(Object delegate, View host, AccessibilityEvent event) { return false; } public void onInitializeAccessibilityEvent(Object delegate, View host, AccessibilityEvent event) { } public void onInitializeAccessibilityNodeInfo(Object delegate, View host, AccessibilityNodeInfoCompat info) { } public void onPopulateAccessibilityEvent(Object delegate, View host, AccessibilityEvent event) { } public boolean onRequestSendAccessibilityEvent(Object delegate, ViewGroup host, View child, AccessibilityEvent event) { return true; } public void sendAccessibilityEvent(Object delegate, View host, int eventType) { } public void sendAccessibilityEventUnchecked(Object delegate, View host, AccessibilityEvent event) { } } static class AccessibilityDelegateIcsImpl extends AccessibilityDelegateStubImpl { @Override public Object newAccessiblityDelegateDefaultImpl() { return AccessibilityDelegateCompatIcs.newAccessibilityDelegateDefaultImpl(); } @Override public Object newAccessiblityDelegateBridge(final AccessibilityDelegateCompat compat) { return AccessibilityDelegateCompatIcs.newAccessibilityDelegateBridge( new AccessibilityDelegateCompatIcs.AccessibilityDelegateBridge() { @Override public boolean dispatchPopulateAccessibilityEvent(View host, AccessibilityEvent event) { return compat.dispatchPopulateAccessibilityEvent(host, event); } @Override public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event) { compat.onInitializeAccessibilityEvent(host, event); } @Override public void onInitializeAccessibilityNodeInfo(View host, Object info) { compat.onInitializeAccessibilityNodeInfo(host, new AccessibilityNodeInfoCompat(info)); } @Override public void onPopulateAccessibilityEvent(View host, AccessibilityEvent event) { compat.onPopulateAccessibilityEvent(host, event); } @Override public boolean onRequestSendAccessibilityEvent(ViewGroup host, View child, AccessibilityEvent event) { return compat.onRequestSendAccessibilityEvent(host, child, event); } @Override public void sendAccessibilityEvent(View host, int eventType) { compat.sendAccessibilityEvent(host, eventType); } @Override public void sendAccessibilityEventUnchecked(View host, AccessibilityEvent event) { compat.sendAccessibilityEventUnchecked(host, event); } }); } @Override public boolean dispatchPopulateAccessibilityEvent(Object delegate, View host, AccessibilityEvent event) { return AccessibilityDelegateCompatIcs.dispatchPopulateAccessibilityEvent(delegate, host, event); } @Override public void onInitializeAccessibilityEvent(Object delegate, View host, AccessibilityEvent event) { AccessibilityDelegateCompatIcs.onInitializeAccessibilityEvent(delegate, host, event); } @Override public void onInitializeAccessibilityNodeInfo(Object delegate, View host, AccessibilityNodeInfoCompat info) { AccessibilityDelegateCompatIcs.onInitializeAccessibilityNodeInfo(delegate, host, info.getImpl()); } @Override public void onPopulateAccessibilityEvent(Object delegate, View host, AccessibilityEvent event) { AccessibilityDelegateCompatIcs.onPopulateAccessibilityEvent(delegate, host, event); } @Override public boolean onRequestSendAccessibilityEvent(Object delegate, ViewGroup host, View child, AccessibilityEvent event) { return AccessibilityDelegateCompatIcs.onRequestSendAccessibilityEvent(delegate, host, child, event); } @Override public void sendAccessibilityEvent(Object delegate, View host, int eventType) { AccessibilityDelegateCompatIcs.sendAccessibilityEvent(delegate, host, eventType); } @Override public void sendAccessibilityEventUnchecked(Object delegate, View host, AccessibilityEvent event) { AccessibilityDelegateCompatIcs.sendAccessibilityEventUnchecked(delegate, host, event); } } private static final AccessibilityDelegateImpl IMPL; private static final Object DEFAULT_DELEGATE; static { if (Build.VERSION.SDK_INT >= 14) { // ICS IMPL = new AccessibilityDelegateIcsImpl(); } else { IMPL = new AccessibilityDelegateStubImpl(); } DEFAULT_DELEGATE = IMPL.newAccessiblityDelegateDefaultImpl(); } final Object mBridge; /** * Creates a new instance. */ public AccessibilityDelegateCompat() { mBridge = IMPL.newAccessiblityDelegateBridge(this); } /** * @return The wrapped bridge implementation. */ Object getBridge() { return mBridge; } /** * Sends an accessibility event of the given type. If accessibility is not * enabled this method has no effect. * <p> * The default implementation behaves as {@link View#sendAccessibilityEvent(int) * View#sendAccessibilityEvent(int)} for the case of no accessibility delegate * been set. * </p> * * @param host The View hosting the delegate. * @param eventType The type of the event to send. * * @see View#sendAccessibilityEvent(int) View#sendAccessibilityEvent(int) */ public void sendAccessibilityEvent(View host, int eventType) { IMPL.sendAccessibilityEvent(DEFAULT_DELEGATE, host, eventType); } /** * Sends an accessibility event. This method behaves exactly as * {@link #sendAccessibilityEvent(View, int)} but takes as an argument an * empty {@link AccessibilityEvent} and does not perform a check whether * accessibility is enabled. * <p> * The default implementation behaves as * {@link View#sendAccessibilityEventUnchecked(AccessibilityEvent) * View#sendAccessibilityEventUnchecked(AccessibilityEvent)} for * the case of no accessibility delegate been set. * </p> * * @param host The View hosting the delegate. * @param event The event to send. * * @see View#sendAccessibilityEventUnchecked(AccessibilityEvent) * View#sendAccessibilityEventUnchecked(AccessibilityEvent) */ public void sendAccessibilityEventUnchecked(View host, AccessibilityEvent event) { IMPL.sendAccessibilityEventUnchecked(DEFAULT_DELEGATE, host, event); } /** * Dispatches an {@link AccessibilityEvent} to the host {@link View} first and then * to its children for adding their text content to the event. * <p> * The default implementation behaves as * {@link View#dispatchPopulateAccessibilityEvent(AccessibilityEvent) * View#dispatchPopulateAccessibilityEvent(AccessibilityEvent)} for * the case of no accessibility delegate been set. * </p> * * @param host The View hosting the delegate. * @param event The event. * @return True if the event population was completed. * * @see View#dispatchPopulateAccessibilityEvent(AccessibilityEvent) * View#dispatchPopulateAccessibilityEvent(AccessibilityEvent) */ public boolean dispatchPopulateAccessibilityEvent(View host, AccessibilityEvent event) { return IMPL.dispatchPopulateAccessibilityEvent(DEFAULT_DELEGATE, host, event); } /** * Gives a chance to the host View to populate the accessibility event with its * text content. * <p> * The default implementation behaves as * {@link ViewCompat#onPopulateAccessibilityEvent(View, AccessibilityEvent) * ViewCompat#onPopulateAccessibilityEvent(AccessibilityEvent)} for * the case of no accessibility delegate been set. * </p> * * @param host The View hosting the delegate. * @param event The accessibility event which to populate. * * @see ViewCompat#onPopulateAccessibilityEvent(View ,AccessibilityEvent) * ViewCompat#onPopulateAccessibilityEvent(View, AccessibilityEvent) */ public void onPopulateAccessibilityEvent(View host, AccessibilityEvent event) { IMPL.onPopulateAccessibilityEvent(DEFAULT_DELEGATE, host, event); } /** * Initializes an {@link AccessibilityEvent} with information about the * the host View which is the event source. * <p> * The default implementation behaves as * {@link ViewCompat#onInitializeAccessibilityEvent(View v, AccessibilityEvent event) * ViewCompat#onInitalizeAccessibilityEvent(View v, AccessibilityEvent event)} for * the case of no accessibility delegate been set. * </p> * * @param host The View hosting the delegate. * @param event The event to initialize. * * @see ViewCompat#onInitializeAccessibilityEvent(View, AccessibilityEvent) * ViewCompat#onInitializeAccessibilityEvent(View, AccessibilityEvent) */ public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event) { IMPL.onInitializeAccessibilityEvent(DEFAULT_DELEGATE, host, event); } /** * Initializes an {@link AccessibilityNodeInfoCompat} with information about the host view. * <p> * The default implementation behaves as * {@link ViewCompat#onInitializeAccessibilityNodeInfo(View, AccessibilityNodeInfoCompat) * ViewCompat#onInitializeAccessibilityNodeInfo(View, AccessibilityNodeInfoCompat)} for * the case of no accessibility delegate been set. * </p> * * @param host The View hosting the delegate. * @param info The instance to initialize. * * @see ViewCompat#onInitializeAccessibilityNodeInfo(View, AccessibilityNodeInfoCompat) * ViewCompat#onInitializeAccessibilityNodeInfo(View, AccessibilityNodeInfoCompat) */ public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) { IMPL.onInitializeAccessibilityNodeInfo(DEFAULT_DELEGATE, host, info); } /** * Called when a child of the host View has requested sending an * {@link AccessibilityEvent} and gives an opportunity to the parent (the host) * to augment the event. * <p> * The default implementation behaves as * {@link ViewGroupCompat#onRequestSendAccessibilityEvent(ViewGroup, View, AccessibilityEvent) * ViewGroupCompat#onRequestSendAccessibilityEvent(ViewGroup, View, AccessibilityEvent)} for * the case of no accessibility delegate been set. * </p> * * @param host The View hosting the delegate. * @param child The child which requests sending the event. * @param event The event to be sent. * @return True if the event should be sent * * @see ViewGroupCompat#onRequestSendAccessibilityEvent(ViewGroup, View, AccessibilityEvent) * ViewGroupCompat#onRequestSendAccessibilityEvent(ViewGroup, View, AccessibilityEvent) */ public boolean onRequestSendAccessibilityEvent(ViewGroup host, View child, AccessibilityEvent event) { return IMPL.onRequestSendAccessibilityEvent(DEFAULT_DELEGATE, host, child, event); } }