/*
* Copyright 2014 Google Inc. All rights reserved.
*
* 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 com.google.samples.apps.iosched.util;
import android.annotation.TargetApi;
import android.graphics.Bitmap;
import android.os.Build;
import android.os.Bundle;
import android.app.Fragment;
import android.app.FragmentManager;
import android.support.v4.util.LruCache;
import com.android.volley.toolbox.ImageLoader;
import static com.google.samples.apps.iosched.util.LogUtils.LOGD;
import static com.google.samples.apps.iosched.util.LogUtils.makeLogTag;
/**
* This class holds our bitmap caches (memory and disk).
*/
public class BitmapCache implements ImageLoader.ImageCache {
private static final String TAG = makeLogTag(BitmapCache.class);
// Default memory cache size as a percent of device memory class
private static final float DEFAULT_MEM_CACHE_PERCENT = 0.15f;
private LruCache<String, Bitmap> mMemoryCache;
/**
* Don't instantiate this class directly, use
* {@link #getInstance(android.support.v4.app.FragmentManager, float)}.
* @param memCacheSize Memory cache size in KB.
*/
private BitmapCache(int memCacheSize) {
init(memCacheSize);
}
/**
* Find and return an existing BitmapCache stored in a {@link RetainFragment}, if not found a
* new one is created using the supplied params and saved to a {@link RetainFragment}.
*
* @param fragmentManager The fragment manager to use when dealing with the retained fragment.
* @param fragmentTag The tag of the retained fragment (should be unique for each memory cache
* that needs to be retained).
* @param memCacheSize Memory cache size in KB.
*/
public static BitmapCache getInstance(FragmentManager fragmentManager, String fragmentTag,
int memCacheSize) {
BitmapCache bitmapCache = null;
RetainFragment mRetainFragment = null;
if (fragmentManager != null) {
// Search for, or create an instance of the non-UI RetainFragment
mRetainFragment = getRetainFragment(fragmentManager, fragmentTag);
// See if we already have a BitmapCache stored in RetainFragment
bitmapCache = (BitmapCache) mRetainFragment.getObject();
}
// No existing BitmapCache, create one and store it in RetainFragment
if (bitmapCache == null) {
bitmapCache = new BitmapCache(memCacheSize);
if (mRetainFragment != null) {
mRetainFragment.setObject(bitmapCache);
}
}
return bitmapCache;
}
public static BitmapCache getInstance(FragmentManager fragmentManager, int memCacheSize) {
return getInstance(fragmentManager, TAG, memCacheSize);
}
public static BitmapCache getInstance(FragmentManager fragmentManager, float memCachePercent) {
return getInstance(fragmentManager, calculateMemCacheSize(memCachePercent));
}
public static BitmapCache getInstance(FragmentManager fragmentManger) {
return getInstance(fragmentManger, DEFAULT_MEM_CACHE_PERCENT);
}
/**
* Initialize the cache.
*/
private void init(int memCacheSize) {
// Set up memory cache
LOGD(TAG, "Memory cache created (size = " + memCacheSize + "KB)");
mMemoryCache = new LruCache<String, Bitmap>(memCacheSize) {
/**
* Measure item size in kilobytes rather than units which is more practical
* for a bitmap cache
*/
@Override
protected int sizeOf(String key, Bitmap bitmap) {
final int bitmapSize = getBitmapSize(bitmap) / 1024;
return bitmapSize == 0 ? 1 : bitmapSize;
}
};
}
/**
* Adds a bitmap to both memory and disk cache.
* @param data Unique identifier for the bitmap to store
* @param bitmap The bitmap to store
*/
public void addBitmapToCache(String data, Bitmap bitmap) {
if (data == null || bitmap == null) {
return;
}
synchronized (mMemoryCache) {
// Add to memory cache
if (mMemoryCache.get(data) == null) {
LOGD(TAG, "Memory cache put - " + data);
mMemoryCache.put(data, bitmap);
}
}
}
/**
* Get from memory cache.
*
* @param data Unique identifier for which item to get
* @return The bitmap if found in cache, null otherwise
*/
public Bitmap getBitmapFromMemCache(String data) {
if (data != null) {
synchronized (mMemoryCache) {
final Bitmap memBitmap = mMemoryCache.get(data);
if (memBitmap != null) {
LOGD(TAG, "Memory cache hit - " + data);
return memBitmap;
}
}
LOGD(TAG, "Memory cache miss - " + data);
}
return null;
}
/**
* Clears the memory cache.
*/
public void clearCache() {
if (mMemoryCache != null) {
mMemoryCache.evictAll();
LOGD(TAG, "Memory cache cleared");
}
}
/**
* Sets the memory cache size based on a percentage of the max available VM memory.
* Eg. setting percent to 0.2 would set the memory cache to one fifth of the available
* memory. Throws {@link IllegalArgumentException} if percent is < 0.05 or > .8.
* memCacheSize is stored in kilobytes instead of bytes as this will eventually be passed
* to construct a LruCache which takes an int in its constructor.
*
* This value should be chosen carefully based on a number of factors
* Refer to the corresponding Android Training class for more discussion:
* http://developer.android.com/training/displaying-bitmaps/
*
* @param percent Percent of memory class to use to size memory cache
* @return Memory cache size in KB
*/
public static int calculateMemCacheSize(float percent) {
if (percent < 0.05f || percent > 0.8f) {
throw new IllegalArgumentException("setMemCacheSizePercent - percent must be "
+ "between 0.05 and 0.8 (inclusive)");
}
return Math.round(percent * Runtime.getRuntime().maxMemory() / 1024);
}
/**
* Get the size in bytes of a bitmap.
*/
public static int getBitmapSize(Bitmap bitmap) {
return bitmap.getByteCount();
}
/**
* Locate an existing instance of this Fragment or if not found, create and
* add it using FragmentManager.
*
* @param fm The FragmentManager manager to use.
* @param fragmentTag The tag of the retained fragment (should be unique for each memory
* cache that needs to be retained).
* @return The existing instance of the Fragment or the new instance if just
* created.
*/
private static RetainFragment getRetainFragment(FragmentManager fm, String fragmentTag) {
// Check to see if we have retained the worker fragment.
RetainFragment mRetainFragment = (RetainFragment) fm.findFragmentByTag(fragmentTag);
// If not retained (or first time running), we need to create and add it.
if (mRetainFragment == null) {
mRetainFragment = new RetainFragment();
fm.beginTransaction().add(mRetainFragment, fragmentTag).commitAllowingStateLoss();
}
return mRetainFragment;
}
@Override
public Bitmap getBitmap(String key) {
return getBitmapFromMemCache(key);
}
@Override
public void putBitmap(String key, Bitmap bitmap) {
addBitmapToCache(key, bitmap);
}
/**
* A simple non-UI Fragment that stores a single Object and is retained over configuration
* changes. It will be used to retain the BitmapCache object.
*/
public static class RetainFragment extends Fragment {
private Object mObject;
/**
* Empty constructor as per the Fragment documentation
*/
public RetainFragment() {}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Make sure this Fragment is retained over a configuration change
setRetainInstance(true);
}
/**
* Store a single object in this Fragment.
*
* @param object The object to store
*/
public void setObject(Object object) {
mObject = object;
}
/**
* Get the stored object.
*
* @return The stored object
*/
public Object getObject() {
return mObject;
}
}
}