Class ImageLoader

xutils/src/main/java/org/xutils/image/ImageLoader.java:40–642

 * 图片加载控制
 */
/*package*/ final class ImageLoader implements
        Callback.PrepareCallback<File, Drawable>,
        Callback.CacheCallback<Drawable>,
        Callback.ProgressCallback<Drawable>,
        Callback.TypedCallback<Drawable>,
        Callback.Cancelable {

    private MemCacheKey key;
    private ImageOptions options;
    private WeakReference<ImageView> viewRef;
    private int fileLockedExceptionRetryCount = 0;

    private final static AtomicLong SEQ_SEEK = new AtomicLong(0);
    private final long seq = SEQ_SEEK.incrementAndGet();

    private volatile boolean stopped = false;
    private volatile boolean cancelled = false;
    private volatile boolean skipOnWaitingCallback = false;
    private volatile boolean skipOnFinishedCallback = false;
    private Callback.Cancelable httpCancelable;
    private Callback.CommonCallback<Drawable> callback;
    private Callback.PrepareCallback<File, Drawable> prepareCallback;
    private Callback.CacheCallback<Drawable> cacheCallback;
    private Callback.ProgressCallback<Drawable> progressCallback;

    private final static String DISK_CACHE_DIR_NAME = "xUtils_img";
    private final static Executor EXECUTOR = new PriorityExecutor(10, false);
    private final static int MEM_CACHE_MIN_SIZE = 1024 * 1024 * 4; // 4M
    private final static LruCache<MemCacheKey, Drawable> MEM_CACHE =
            new LruCache<MemCacheKey, Drawable>(MEM_CACHE_MIN_SIZE) {
                private boolean deepClear = false;

                @Override
                protected int sizeOf(MemCacheKey key, Drawable value) {
                    if (value instanceof BitmapDrawable) {
                        Bitmap bitmap = ((BitmapDrawable) value).getBitmap();
                        return bitmap == null ? 0 : bitmap.getByteCount();
                    } else if (value instanceof GifDrawable) {
                        return ((GifDrawable) value).getByteCount();
                    }
                    return super.sizeOf(key, value);
                }

                @Override
                public void trimToSize(int maxSize) {
                    if (maxSize < 0) {
                        deepClear = true;
                    }
                    super.trimToSize(maxSize);
                    deepClear = false;
                }

                @Override
                protected void entryRemoved(boolean evicted, MemCacheKey key, Drawable oldValue, Drawable newValue) {
                    super.entryRemoved(evicted, key, oldValue, newValue);
                    if (evicted && deepClear && oldValue instanceof ReusableDrawable) {
                        ((ReusableDrawable) oldValue).setMemCacheKey(null);
                    }