CacheBitmapLoader.java
/*
* Copyright 2022 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
*
* https://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 androidx.media3.session;
import static androidx.media3.common.util.Assertions.checkStateNotNull;
import android.graphics.Bitmap;
import android.net.Uri;
import androidx.annotation.Nullable;
import androidx.media3.common.util.UnstableApi;
import com.google.common.util.concurrent.ListenableFuture;
import java.util.Arrays;
import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
/**
* A {@link BitmapLoader} that caches the result of the last {@link #decodeBitmap(byte[])} or {@link
* #loadBitmap(Uri)} request. Requests are fulfilled from the last bitmap load request when the last
* bitmap is requested from the same {@code data} or the last bitmap is requested from the same
* {@code uri}. If it's not the above two cases, the request is forwarded to the provided {@link
* BitmapLoader} and the result is cached.
*/
@UnstableApi
public final class CacheBitmapLoader implements BitmapLoader {
private final BitmapLoader bitmapLoader;
private @MonotonicNonNull BitmapLoadRequest lastBitmapLoadRequest;
/**
* Creates an instance that is able to cache the last bitmap load request to the given bitmap
* loader.
*/
public CacheBitmapLoader(BitmapLoader bitmapLoader) {
this.bitmapLoader = bitmapLoader;
}
@Override
public ListenableFuture<Bitmap> decodeBitmap(byte[] data) {
if (lastBitmapLoadRequest != null && lastBitmapLoadRequest.matches(data)) {
return lastBitmapLoadRequest.getFuture();
}
ListenableFuture<Bitmap> future = bitmapLoader.decodeBitmap(data);
lastBitmapLoadRequest = new BitmapLoadRequest(data, future);
return future;
}
@Override
public ListenableFuture<Bitmap> loadBitmap(Uri uri) {
if (lastBitmapLoadRequest != null && lastBitmapLoadRequest.matches(uri)) {
return lastBitmapLoadRequest.getFuture();
}
ListenableFuture<Bitmap> future = bitmapLoader.loadBitmap(uri);
lastBitmapLoadRequest = new BitmapLoadRequest(uri, future);
return future;
}
/**
* Stores the result of a bitmap load request. Requests are identified either by a byte array, if
* the bitmap is loaded from compressed data, or a URI, if the bitmap was loaded from a URI.
*/
private static class BitmapLoadRequest {
@Nullable private final byte[] data;
@Nullable private final Uri uri;
@Nullable private final ListenableFuture<Bitmap> future;
public BitmapLoadRequest(byte[] data, ListenableFuture<Bitmap> future) {
this.data = data;
this.uri = null;
this.future = future;
}
public BitmapLoadRequest(Uri uri, ListenableFuture<Bitmap> future) {
this.data = null;
this.uri = uri;
this.future = future;
}
/** Whether the bitmap load request was performed for {@code data}. */
public boolean matches(@Nullable byte[] data) {
return this.data != null && Arrays.equals(this.data, data);
}
/** Whether the bitmap load request was performed for {@code uri}. */
public boolean matches(@Nullable Uri uri) {
return this.uri != null && this.uri.equals(uri);
}
/** Returns the future that set for the bitmap load request. */
public ListenableFuture<Bitmap> getFuture() {
return checkStateNotNull(future);
}
}
}