in DisplayingBitmaps/Application/src/main/java/com/example/android/displayingbitmaps/util/ImageCache.java [132:197]
private void init(ImageCacheParams cacheParams) {
mCacheParams = cacheParams;
//BEGIN_INCLUDE(init_memory_cache)
// Set up memory cache
if (mCacheParams.memoryCacheEnabled) {
if (BuildConfig.DEBUG) {
Log.d(TAG, "Memory cache created (size = " + mCacheParams.memCacheSize + ")");
}
// If we're running on Honeycomb or newer, create a set of reusable bitmaps that can be
// populated into the inBitmap field of BitmapFactory.Options. Note that the set is
// of SoftReferences which will actually not be very effective due to the garbage
// collector being aggressive clearing Soft/WeakReferences. A better approach
// would be to use a strongly references bitmaps, however this would require some
// balancing of memory usage between this set and the bitmap LruCache. It would also
// require knowledge of the expected size of the bitmaps. From Honeycomb to JellyBean
// the size would need to be precise, from KitKat onward the size would just need to
// be the upper bound (due to changes in how inBitmap can re-use bitmaps).
mReusableBitmaps =
Collections.synchronizedSet(new HashSet<SoftReference<Bitmap>>());
mMemoryCache = new LruCache<String, BitmapDrawable>(mCacheParams.memCacheSize) {
/**
* Notify the removed entry that is no longer being cached
*/
@Override
protected void entryRemoved(
boolean evicted,
@NonNull String key,
@NonNull BitmapDrawable oldValue,
BitmapDrawable newValue
) {
if (oldValue instanceof RecyclingBitmapDrawable) {
// The removed entry is a recycling drawable, so notify it
// that it has been removed from the memory cache
((RecyclingBitmapDrawable) oldValue).setIsCached(false);
} else {
// The removed entry is a standard BitmapDrawable.
// Add the bitmap to a SoftReference set for possible use with inBitmap
// later.
mReusableBitmaps.add(new SoftReference<>(oldValue.getBitmap()));
}
}
/**
* Measure item size in kilobytes rather than units which is more practical
* for a bitmap cache
*/
@Override
protected int sizeOf(@NonNull String key, @NonNull BitmapDrawable value) {
final int bitmapSize = getBitmapSize(value) / 1024;
return bitmapSize == 0 ? 1 : bitmapSize;
}
};
}
//END_INCLUDE(init_memory_cache)
// By default the disk cache is not initialized here as it should be initialized
// on a separate thread due to disk access.
if (cacheParams.initDiskCacheOnCreate) {
// Set up disk cache
initDiskCache();
}
}