/*
* 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 org.nativescript.widgets.image;
import android.Manifest;
import android.annotation.TargetApi;
import android.content.Context;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.os.Build.VERSION_CODES;
import android.os.Environment;
import android.os.StatFs;
import android.support.v4.util.LruCache;
import android.util.Log;
import java.io.File;
import java.lang.ref.SoftReference;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/**
* This class handles disk and memory caching of bitmaps in conjunction with the
* {@link Worker} class and its subclasses. Use
* {@link Cache#getInstance(CacheParams)} to get an instance of this
* class, although usually a cache should be added directly to an {@link Worker} by calling
* {@link Worker#addImageCache(Cache)}.
*/
public class Cache {
private static final String TAG = "JS";
// Default memory cache size in kilobytes
private static final int DEFAULT_MEM_CACHE_SIZE = 1024 * 5; // 5MB
// Constants to easily toggle various caches
private static final boolean DEFAULT_MEM_CACHE_ENABLED = true;
private static final boolean DEFAULT_DISK_CACHE_ENABLED = true;
private static Cache instance;
private HashMap<String, Integer> mMemoryCacheUsage;
private LruCache<String, Bitmap> mMemoryCache;
private CacheParams mParams;
private Set<SoftReference<Bitmap>> mReusableBitmaps;
/**
* Create a new Cache object using the specified parameters. This should not be
* called directly by other classes, instead use
* {@link Cache#getInstance(CacheParams)} to fetch an Cache
* instance.
*/
private Cache() {
}
/**
* Return an {@link Cache} instance.
*
* @return An existing retained Cache object or a new one if one did not exist
*/
public static Cache getInstance(CacheParams cacheParams) {
if (instance == null) {
instance = new Cache();
}
if (instance.mParams != cacheParams) {
instance.init(cacheParams);
}
return instance;
}
/**
* Initialize the cache, providing all parameters.
*
* @param cacheParams The cache parameters to initialize the cache
*/
private void init(CacheParams cacheParams) {
clearCache();
if (mReusableBitmaps != null) {
mReusableBitmaps.clear();
mReusableBitmaps = null;
}
mParams = cacheParams;
// Set up memory cache
if (mParams.memoryCacheEnabled) {
if (Worker.debuggable > 0) {
Log.v(TAG, "Memory cache created (size = " + mParams.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).
if (Utils.hasHoneycomb()) {
mReusableBitmaps =
Collections.synchronizedSet(new HashSet<SoftReference<Bitmap>>());
}
mMemoryCacheUsage = new HashMap<String, Integer>();
mMemoryCache = new LruCache<String, Bitmap>(mParams.memCacheSize) {
/**
* Notify the removed entry that is no longer being cached
*/
@Override
protected void entryRemoved(boolean evicted, String key,
Bitmap oldValue, Bitmap newValue) {
Integer count = mMemoryCacheUsage.get(key);
if (Utils.hasHoneycomb() && (count == null || count == 0)) {
// We're running on Honeycomb or later, so add the bitmap
// to a SoftReference set for possible use with inBitmap later
mReusableBitmaps.add(new SoftReference<Bitmap>(oldValue));
}
}
/**
* Measure item size in kilobytes rather than units which is more practical
* for a bitmap cache
*/
@Override
protected int sizeOf(String key, Bitmap value) {
final int bitmapSize = getBitmapSize(value) / 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 value The bitmap drawable to store
*/
public void addBitmapToCache(String data, Bitmap value) {
if (data == null || value == null) {
return;
}
// Add to memory cache
if (mMemoryCache != null) {
Bitmap currentValue = mMemoryCache.get(data);
// NOTE: If we have existing we probably loaded it sync so we don't want to add the new one,
// because this will make the previous bitmap free for reuse but it is used somewhere.
// Probably won't happen often.
if (currentValue == null) {
Integer count = mMemoryCacheUsage.get(data);
// NOTE: count should be null here.
mMemoryCacheUsage.put(data, count == null ? 1 : count + 1);
mMemoryCache.put(data, value);
}
}
}
/**
* 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) {
Bitmap memValue = null;
if (mMemoryCache != null) {
memValue = mMemoryCache.get(data);
if (memValue != null) {
Integer count = mMemoryCacheUsage.get(data);
mMemoryCacheUsage.put(data, count == null ? 1 : count + 1);
}
}
if (Worker.debuggable > 0 && memValue != null) {
Log.v(TAG, "Memory cache hit");
}
return memValue;
}
public void reduceDisplayedCounter(String uri) {
if (mMemoryCache != null) {
Integer count = mMemoryCacheUsage.get(uri);
if (count != null) {
if (count == 1) {
mMemoryCacheUsage.remove(uri);
} else {
mMemoryCacheUsage.put(uri, count - 1);
}
}
}
}
/**
* @param options - BitmapFactory.Options with out* options populated
* @return Bitmap that case be used for inBitmap
*/
protected Bitmap getBitmapFromReusableSet(BitmapFactory.Options options) {
//BEGIN_INCLUDE(get_bitmap_from_reusable_set)
Bitmap bitmap = null;
if (mReusableBitmaps != null && !mReusableBitmaps.isEmpty()) {
synchronized (mReusableBitmaps) {
final Iterator<SoftReference<Bitmap>> iterator = mReusableBitmaps.iterator();
Bitmap item;
while (iterator.hasNext()) {
item = iterator.next().get();
if (null != item && item.isMutable()) {
// Check to see it the item can be used for inBitmap
if (canUseForInBitmap(item, options)) {
bitmap = item;
// Remove from reusable set so it can't be used again
iterator.remove();
break;
}
} else {
// Remove from the set if the reference has been cleared.
iterator.remove();
}
}
}
}
return bitmap;
//END_INCLUDE(get_bitmap_from_reusable_set)
}
/**
* Clears both the memory and disk cache associated with this Cache object. Note that
* this includes disk access so this should not be executed on the main/UI thread.
*/
public void clearCache() {
if (mMemoryCache != null) {
mMemoryCache.evictAll();
if (Worker.debuggable > 0) {
Log.v(TAG, "Memory cache cleared");
}
}
if (mMemoryCacheUsage != null) {
mMemoryCacheUsage.clear();
}
mMemoryCacheUsage = null;
mMemoryCache = null;
}
/**
* A holder class that contains cache parameters.
*/
public static class CacheParams {
public int memCacheSize = DEFAULT_MEM_CACHE_SIZE;
public boolean memoryCacheEnabled = DEFAULT_MEM_CACHE_ENABLED;
public boolean diskCacheEnabled = DEFAULT_DISK_CACHE_ENABLED;
/**
* 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 < 0.01 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.
* <p>
* 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 available app memory to use to size memory cache
*/
public void setMemCacheSizePercent(float percent) {
if (percent < 0.01f || percent > 0.8f) {
throw new IllegalArgumentException("setMemCacheSizePercent - percent must be "
+ "between 0.01 and 0.8 (inclusive)");
}
memCacheSize = Math.round(percent * Runtime.getRuntime().maxMemory() / 1024);
}
}
/**
* @param candidate - Bitmap to check
* @param targetOptions - Options that have the out* value populated
* @return true if <code>candidate</code> can be used for inBitmap re-use with
* <code>targetOptions</code>
*/
@TargetApi(VERSION_CODES.KITKAT)
private static boolean canUseForInBitmap(
Bitmap candidate, BitmapFactory.Options targetOptions) {
//BEGIN_INCLUDE(can_use_for_inbitmap)
if (!Utils.hasKitKat()) {
// On earlier versions, the dimensions must match exactly and the inSampleSize must be 1
return candidate.getWidth() == targetOptions.outWidth
&& candidate.getHeight() == targetOptions.outHeight
&& targetOptions.inSampleSize == 1;
}
// From Android 4.4 (KitKat) onward we can re-use if the byte size of the new bitmap
// is smaller than the reusable bitmap candidate allocation byte count.
int width = targetOptions.outWidth / targetOptions.inSampleSize;
int height = targetOptions.outHeight / targetOptions.inSampleSize;
int byteCount = width * height * getBytesPerPixel(candidate.getConfig());
return byteCount <= candidate.getAllocationByteCount();
//END_INCLUDE(can_use_for_inbitmap)
}
/**
* Return the byte usage per pixel of a bitmap based on its configuration.
*
* @param config The bitmap configuration.
* @return The byte usage per pixel.
*/
private static int getBytesPerPixel(Config config) {
if (config == Config.ARGB_8888) {
return 4;
} else if (config == Config.RGB_565) {
return 2;
} else if (config == Config.ARGB_4444) {
return 2;
} else if (config == Config.ALPHA_8) {
return 1;
}
return 1;
}
/**
* Get a usable cache directory (external if available, internal otherwise).
*
* @param context The context to use
* @param uniqueName A unique directory name to append to the cache dir
* @return The cache dir
*/
public static File getDiskCacheDir(Context context, String uniqueName) {
// Check if media is mounted or storage is built-in, if so, try and use external cache dir
// otherwise use internal cache dir
final File cacheFilePath = Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState()) ||
!isExternalStorageRemovable() ? getExternalCacheDir(context) : context.getCacheDir();
// In case there is no external storage isExternalStorageRemovable returns False and we get Null from getExternalCacheDir.
// If this is the case - fall back to internal cache dir.
final String cachePath = cacheFilePath != null ? cacheFilePath.getPath() : context.getCacheDir().getPath();
return new File(cachePath + File.separator + uniqueName);
}
/**
* A hashing method that changes a string (like a URL) into a hash suitable for using as a
* disk filename.
*/
public static String hashKeyForDisk(String key) {
String cacheKey;
try {
final MessageDigest mDigest = MessageDigest.getInstance("MD5");
mDigest.update(key.getBytes());
cacheKey = bytesToHexString(mDigest.digest());
} catch (NoSuchAlgorithmException e) {
cacheKey = String.valueOf(key.hashCode());
}
return cacheKey;
}
private static String bytesToHexString(byte[] bytes) {
// http://stackoverflow.com/questions/332079
StringBuilder sb = new StringBuilder();
for (int i = 0; i < bytes.length; i++) {
String hex = Integer.toHexString(0xFF & bytes[i]);
if (hex.length() == 1) {
sb.append('0');
}
sb.append(hex);
}
return sb.toString();
}
/**
* Get the size in bytes of a bitmap in a BitmapDrawable. Note that from Android 4.4 (KitKat)
* onward this returns the allocated memory size of the bitmap which can be larger than the
* actual bitmap data byte count (in the case it was re-used).
*
* @param bitmap
* @return size in bytes
*/
@TargetApi(VERSION_CODES.KITKAT)
public static int getBitmapSize(Bitmap bitmap) {
// From KitKat onward use getAllocationByteCount() as allocated bytes can potentially be
// larger than bitmap byte count.
if (Utils.hasKitKat()) {
return bitmap.getAllocationByteCount();
}
if (Utils.hasHoneycombMR1()) {
return bitmap.getByteCount();
}
// Pre HC-MR1
return bitmap.getRowBytes() * bitmap.getHeight();
}
/**
* Check if external storage is built-in or removable.
*
* @return True if external storage is removable (like an SD card), false
* otherwise.
*/
@TargetApi(VERSION_CODES.GINGERBREAD)
public static boolean isExternalStorageRemovable() {
if (Utils.hasGingerbread()) {
return Environment.isExternalStorageRemovable();
}
return true;
}
/**
* Get the external app cache directory.
*
* @param context The context to use
* @return The external cache dir
*/
@TargetApi(VERSION_CODES.FROYO)
public static File getExternalCacheDir(Context context) {
if (Utils.hasFroyo()) {
if (Utils.hasKitKat() ||
context.checkPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE, android.os.Process.myPid(), android.os.Process.myUid()) == PackageManager.PERMISSION_GRANTED) {
return context.getExternalCacheDir();
}
return null;
}
// Before Froyo we need to construct the external cache dir ourselves
final String cacheDir = "/Android/data/" + context.getPackageName() + "/cache/";
return new File(Environment.getExternalStorageDirectory().getPath() + cacheDir);
}
/**
* Check how much usable space is available at a given path.
*
* @param path The path to check
* @return The space available in bytes
*/
@TargetApi(VERSION_CODES.GINGERBREAD)
public static long getUsableSpace(File path) {
if (Utils.hasGingerbread()) {
return path.getUsableSpace();
}
final StatFs stats = new StatFs(path.getPath());
return (long) stats.getBlockSize() * (long) stats.getAvailableBlocks();
}
}
