/* * Copyright (C) 2012 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.view.accessibility; import android.os.Build; import android.util.Log; import android.util.LongSparseArray; import android.util.SparseLongArray; import java.util.HashSet; import java.util.LinkedList; import java.util.Queue; /** * Simple cache for AccessibilityNodeInfos. The cache is mapping an * accessibility id to an info. The cache allows storing of * null values. It also tracks accessibility events * and invalidates accordingly. * * @hide */ public class AccessibilityNodeInfoCache { private static final String LOG_TAG = AccessibilityNodeInfoCache.class.getSimpleName(); private static final boolean ENABLED = true; private static final boolean DEBUG = false; private static final boolean CHECK_INTEGRITY_IF_DEBUGGABLE_BUILD = true; private final Object mLock = new Object(); private final LongSparseArray mCacheImpl; private int mWindowId; public AccessibilityNodeInfoCache() { if (ENABLED) { mCacheImpl = new LongSparseArray(); } else { mCacheImpl = null; } } /** * The cache keeps track of {@link AccessibilityEvent}s and invalidates * cached nodes as appropriate. * * @param event An event. */ public void onAccessibilityEvent(AccessibilityEvent event) { if (ENABLED) { final int eventType = event.getEventType(); switch (eventType) { case AccessibilityEvent.TYPE_TOUCH_EXPLORATION_GESTURE_END: case AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED: case AccessibilityEvent.TYPE_VIEW_HOVER_ENTER: case AccessibilityEvent.TYPE_VIEW_HOVER_EXIT: { // If the active window changes, clear the cache. final int windowId = event.getWindowId(); if (mWindowId != windowId) { mWindowId = windowId; clear(); } } break; case AccessibilityEvent.TYPE_VIEW_FOCUSED: case AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUSED: case AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUS_CLEARED: case AccessibilityEvent.TYPE_VIEW_SELECTED: case AccessibilityEvent.TYPE_VIEW_TEXT_CHANGED: case AccessibilityEvent.TYPE_VIEW_TEXT_SELECTION_CHANGED: { refreshCachedNode(event.getSourceNodeId()); } break; case AccessibilityEvent.TYPE_VIEW_SCROLLED: { synchronized (mLock) { clearSubTreeLocked(event.getSourceNodeId()); } } break; case AccessibilityEvent.TYPE_WINDOW_CONTENT_CHANGED: { synchronized (mLock) { final long sourceId = event.getSourceNodeId(); if ((event.getContentChangeTypes() & AccessibilityEvent.CONTENT_CHANGE_TYPE_SUBTREE) != 0) { clearSubTreeLocked(sourceId); } else { refreshCachedNode(sourceId); } } } break; } if (CHECK_INTEGRITY_IF_DEBUGGABLE_BUILD && Build.IS_DEBUGGABLE) { checkIntegrity(); } } } private void refreshCachedNode(long sourceId) { if (DEBUG) { Log.i(LOG_TAG, "Refreshing cached node."); } synchronized (mLock) { AccessibilityNodeInfo cachedInfo = mCacheImpl.get(sourceId); // If the source is not in the cache - nothing to do. if (cachedInfo == null) { return; } // The node changed so we will just refresh it right now. if (cachedInfo.refresh(true)) { return; } // Weird, we could not refresh. Just evict the entire sub-tree. clearSubTreeLocked(sourceId); } } /** * Gets a cached {@link AccessibilityNodeInfo} given its accessibility node id. * * @param accessibilityNodeId The info accessibility node id. * @return The cached {@link AccessibilityNodeInfo} or null if such not found. */ public AccessibilityNodeInfo get(long accessibilityNodeId) { if (ENABLED) { synchronized(mLock) { AccessibilityNodeInfo info = mCacheImpl.get(accessibilityNodeId); if (info != null) { // Return a copy since the client calls to AccessibilityNodeInfo#recycle() // will wipe the data of the cached info. info = AccessibilityNodeInfo.obtain(info); } if (DEBUG) { Log.i(LOG_TAG, "get(" + accessibilityNodeId + ") = " + info); } return info; } } else { return null; } } /** * Caches an {@link AccessibilityNodeInfo} given its accessibility node id. * * @param info The {@link AccessibilityNodeInfo} to cache. */ public void add(AccessibilityNodeInfo info) { if (ENABLED) { synchronized(mLock) { if (DEBUG) { Log.i(LOG_TAG, "add(" + info + ")"); } final long sourceId = info.getSourceNodeId(); AccessibilityNodeInfo oldInfo = mCacheImpl.get(sourceId); if (oldInfo != null) { // If the added node is in the cache we have to be careful if // the new one represents a source state where some of the // children have been removed to avoid having disconnected // subtrees in the cache. SparseLongArray oldChildrenIds = oldInfo.getChildNodeIds(); SparseLongArray newChildrenIds = info.getChildNodeIds(); final int oldChildCount = oldChildrenIds.size(); for (int i = 0; i < oldChildCount; i++) { final long oldChildId = oldChildrenIds.valueAt(i); if (newChildrenIds.indexOfValue(oldChildId) < 0) { clearSubTreeLocked(oldChildId); } } // Also be careful if the parent has changed since the new // parent may be a predecessor of the old parent which will // make the cached tree cyclic. final long oldParentId = oldInfo.getParentNodeId(); if (info.getParentNodeId() != oldParentId) { clearSubTreeLocked(oldParentId); } } // Cache a copy since the client calls to AccessibilityNodeInfo#recycle() // will wipe the data of the cached info. AccessibilityNodeInfo clone = AccessibilityNodeInfo.obtain(info); mCacheImpl.put(sourceId, clone); } } } /** * Clears the cache. */ public void clear() { if (ENABLED) { synchronized(mLock) { if (DEBUG) { Log.i(LOG_TAG, "clear()"); } // Recycle the nodes before clearing the cache. final int nodeCount = mCacheImpl.size(); for (int i = 0; i < nodeCount; i++) { AccessibilityNodeInfo info = mCacheImpl.valueAt(i); info.recycle(); } mCacheImpl.clear(); } } } /** * Clears a subtree rooted at the node with the given id. * * @param rootNodeId The root id. */ private void clearSubTreeLocked(long rootNodeId) { if (DEBUG) { Log.i(LOG_TAG, "Clearing cached subtree."); } clearSubTreeRecursiveLocked(rootNodeId); } private void clearSubTreeRecursiveLocked(long rootNodeId) { AccessibilityNodeInfo current = mCacheImpl.get(rootNodeId); if (current == null) { return; } mCacheImpl.remove(rootNodeId); SparseLongArray childNodeIds = current.getChildNodeIds(); final int childCount = childNodeIds.size(); for (int i = 0; i < childCount; i++) { final long childNodeId = childNodeIds.valueAt(i); clearSubTreeRecursiveLocked(childNodeId); } } /** * Check the integrity of the cache which is it does not have nodes * from more than one window, there are no duplicates, all nodes are * connected, there is a single input focused node, and there is a * single accessibility focused node. */ private void checkIntegrity() { synchronized (mLock) { // Get the root. if (mCacheImpl.size() <= 0) { return; } // If the cache is a tree it does not matter from // which node we start to search for the root. AccessibilityNodeInfo root = mCacheImpl.valueAt(0); AccessibilityNodeInfo parent = root; while (parent != null) { root = parent; parent = mCacheImpl.get(parent.getParentNodeId()); } // Traverse the tree and do some checks. final int windowId = root.getWindowId(); AccessibilityNodeInfo accessFocus = null; AccessibilityNodeInfo inputFocus = null; HashSet seen = new HashSet(); Queue fringe = new LinkedList(); fringe.add(root); while (!fringe.isEmpty()) { AccessibilityNodeInfo current = fringe.poll(); // Check for duplicates if (!seen.add(current)) { Log.e(LOG_TAG, "Duplicate node: " + current); return; } // Check for one accessibility focus. if (current.isAccessibilityFocused()) { if (accessFocus != null) { Log.e(LOG_TAG, "Duplicate accessibility focus:" + current); } else { accessFocus = current; } } // Check for one input focus. if (current.isFocused()) { if (inputFocus != null) { Log.e(LOG_TAG, "Duplicate input focus: " + current); } else { inputFocus = current; } } SparseLongArray childIds = current.getChildNodeIds(); final int childCount = childIds.size(); for (int i = 0; i < childCount; i++) { final long childId = childIds.valueAt(i); AccessibilityNodeInfo child = mCacheImpl.get(childId); if (child != null) { fringe.add(child); } } } // Check for disconnected nodes or ones from another window. for (int i = 0; i < mCacheImpl.size(); i++) { AccessibilityNodeInfo info = mCacheImpl.valueAt(i); if (!seen.contains(info)) { if (info.getWindowId() == windowId) { Log.e(LOG_TAG, "Disconneced node: " + info); } else { Log.e(LOG_TAG, "Node from: " + info.getWindowId() + " not from:" + windowId + " " + info); } } } } } }