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Diffstat (limited to 'core/java/android/content/res/ThemedResourceCache.java')
| -rw-r--r-- | core/java/android/content/res/ThemedResourceCache.java | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/core/java/android/content/res/ThemedResourceCache.java b/core/java/android/content/res/ThemedResourceCache.java new file mode 100644 index 0000000..9a2d06147 --- /dev/null +++ b/core/java/android/content/res/ThemedResourceCache.java @@ -0,0 +1,233 @@ +/* + * Copyright (C) 2015 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.content.res; + +import android.annotation.NonNull; +import android.annotation.Nullable; +import android.content.res.Resources.Theme; +import android.content.res.Resources.ThemeKey; +import android.util.LongSparseArray; +import android.util.ArrayMap; + +import java.lang.ref.WeakReference; + +/** + * Data structure used for caching data against themes. + * + * @param <T> type of data to cache + */ +abstract class ThemedResourceCache<T> { + private ArrayMap<ThemeKey, LongSparseArray<WeakReference<T>>> mThemedEntries; + private LongSparseArray<WeakReference<T>> mUnthemedEntries; + private LongSparseArray<WeakReference<T>> mNullThemedEntries; + + /** + * Adds a new theme-dependent entry to the cache. + * + * @param key a key that uniquely identifies the entry + * @param theme the theme against which this entry was inflated, or + * {@code null} if the entry has no theme applied + * @param entry the entry to cache + */ + public void put(long key, @Nullable Theme theme, @NonNull T entry) { + put(key, theme, entry, true); + } + + /** + * Adds a new entry to the cache. + * + * @param key a key that uniquely identifies the entry + * @param theme the theme against which this entry was inflated, or + * {@code null} if the entry has no theme applied + * @param entry the entry to cache + * @param usesTheme {@code true} if the entry is affected theme changes, + * {@code false} otherwise + */ + public void put(long key, @Nullable Theme theme, @NonNull T entry, boolean usesTheme) { + if (entry == null) { + return; + } + + synchronized (this) { + final LongSparseArray<WeakReference<T>> entries; + if (!usesTheme) { + entries = getUnthemedLocked(true); + } else { + entries = getThemedLocked(theme, true); + } + if (entries != null) { + entries.put(key, new WeakReference<>(entry)); + } + } + } + + /** + * Returns an entry from the cache. + * + * @param key a key that uniquely identifies the entry + * @param theme the theme where the entry will be used + * @return a cached entry, or {@code null} if not in the cache + */ + @Nullable + public T get(long key, @Nullable Theme theme) { + // The themed (includes null-themed) and unthemed caches are mutually + // exclusive, so we'll give priority to whichever one we think we'll + // hit first. Since most of the framework drawables are themed, that's + // probably going to be the themed cache. + synchronized (this) { + final LongSparseArray<WeakReference<T>> themedEntries = getThemedLocked(theme, false); + if (themedEntries != null) { + final WeakReference<T> themedEntry = themedEntries.get(key); + if (themedEntry != null) { + return themedEntry.get(); + } + } + + final LongSparseArray<WeakReference<T>> unthemedEntries = getUnthemedLocked(false); + if (unthemedEntries != null) { + final WeakReference<T> unthemedEntry = unthemedEntries.get(key); + if (unthemedEntry != null) { + return unthemedEntry.get(); + } + } + } + + return null; + } + + /** + * Prunes cache entries that have been invalidated by a configuration + * change. + * + * @param configChanges a bitmask of configuration changes + */ + public void onConfigurationChange(int configChanges) { + prune(configChanges); + } + + /** + * Returns whether a cached entry has been invalidated by a configuration + * change. + * + * @param entry a cached entry + * @param configChanges a non-zero bitmask of configuration changes + * @return {@code true} if the entry is invalid, {@code false} otherwise + */ + protected abstract boolean shouldInvalidateEntry(@NonNull T entry, int configChanges); + + /** + * Returns the cached data for the specified theme, optionally creating a + * new entry if one does not already exist. + * + * @param t the theme for which to return cached data + * @param create {@code true} to create an entry if one does not already + * exist, {@code false} otherwise + * @return the cached data for the theme, or {@code null} if the cache is + * empty and {@code create} was {@code false} + */ + @Nullable + private LongSparseArray<WeakReference<T>> getThemedLocked(@Nullable Theme t, boolean create) { + if (t == null) { + if (mNullThemedEntries == null && create) { + mNullThemedEntries = new LongSparseArray<>(1); + } + return mNullThemedEntries; + } + + if (mThemedEntries == null) { + if (create) { + mThemedEntries = new ArrayMap<>(1); + } else { + return null; + } + } + + final ThemeKey key = t.getKey(); + LongSparseArray<WeakReference<T>> cache = mThemedEntries.get(key); + if (cache == null && create) { + cache = new LongSparseArray<>(1); + + final ThemeKey keyClone = key.clone(); + mThemedEntries.put(keyClone, cache); + } + + return cache; + } + + /** + * Returns the theme-agnostic cached data. + * + * @param create {@code true} to create an entry if one does not already + * exist, {@code false} otherwise + * @return the theme-agnostic cached data, or {@code null} if the cache is + * empty and {@code create} was {@code false} + */ + @Nullable + private LongSparseArray<WeakReference<T>> getUnthemedLocked(boolean create) { + if (mUnthemedEntries == null && create) { + mUnthemedEntries = new LongSparseArray<>(1); + } + return mUnthemedEntries; + } + + /** + * Prunes cache entries affected by configuration changes or where weak + * references have expired. + * + * @param configChanges a bitmask of configuration changes, or {@code 0} to + * simply prune missing weak references + * @return {@code true} if the cache is completely empty after pruning + */ + private boolean prune(int configChanges) { + synchronized (this) { + if (mThemedEntries != null) { + for (int i = mThemedEntries.size() - 1; i >= 0; i--) { + if (pruneEntriesLocked(mThemedEntries.valueAt(i), configChanges)) { + mThemedEntries.removeAt(i); + } + } + } + + pruneEntriesLocked(mNullThemedEntries, configChanges); + pruneEntriesLocked(mUnthemedEntries, configChanges); + + return mThemedEntries == null && mNullThemedEntries == null + && mUnthemedEntries == null; + } + } + + private boolean pruneEntriesLocked(@Nullable LongSparseArray<WeakReference<T>> entries, + int configChanges) { + if (entries == null) { + return true; + } + + for (int i = entries.size() - 1; i >= 0; i--) { + final WeakReference<T> ref = entries.valueAt(i); + if (ref == null || pruneEntryLocked(ref.get(), configChanges)) { + entries.removeAt(i); + } + } + + return entries.size() == 0; + } + + private boolean pruneEntryLocked(@Nullable T entry, int configChanges) { + return entry == null || (configChanges != 0 + && shouldInvalidateEntry(entry, configChanges)); + } +} |