RequestKey.java revision 25ad6f98516a7af1ca71cfa07fb503d46dc8a7f1 
1/*
2 * Copyright (C) 2013 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.bitmap;
18
19import android.content.res.AssetFileDescriptor;
20
21
22import java.io.IOException;
23import java.io.InputStream;
24
25/**
26 * The decode task uses this class to get input to decode. You must implement at least one of
27 * {@link #createFd()} or {@link #createInputStream()}. {@link DecodeTask} will prioritize
28 * {@link #createFd()} before falling back to {@link #createInputStream()}.
29 * <p>
30 * Objects of this type will also serve as cache keys to fetch cached data for {@link PooledCache}s,
31 * so they must implement {@link #equals(Object)} and {@link #hashCode()}.
32 * <p>
33 * Clients of this interface must also implement {@link #equals(Object)} and {@link #hashCode()} as
34 * this object will be used as a cache key.
35 */
36
37public interface RequestKey {
38    /**
39     * Create an {@link AssetFileDescriptor} for a local file stored on the device. This method will
40     * be called first; if it returns null, {@link #createInputStream()} will be called.
41     */
42    public AssetFileDescriptor createFd() throws IOException;
43
44    /**
45     * Create an {@link InputStream} for a file. This method will be called if {@link #createFd()}
46     * returns null.
47     */
48    public InputStream createInputStream() throws IOException;
49
50    /**
51     * Return true if the image source may have be oriented in either portrait or landscape, and
52     * will need to be automatically re-oriented based on accompanying Exif metadata.
53     */
54    public boolean hasOrientationExif() throws IOException;
55}