DataSource.h revision 5a1c3529e4fa2f8a11054181294e0ce79fff8dd3 
1/*
2 * Copyright (C) 2009 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
17#ifndef DATA_SOURCE_H_
18
19#define DATA_SOURCE_H_
20
21#include <sys/types.h>
22
23#include <utils/Errors.h>
24#include <utils/KeyedVector.h>
25#include <utils/List.h>
26#include <utils/RefBase.h>
27#include <utils/threads.h>
28
29namespace android {
30
31struct AMessage;
32class String8;
33
34class DataSource : public RefBase {
35public:
36    enum Flags {
37        kWantsPrefetching      = 1,
38        kStreamedFromLocalHost = 2,
39    };
40
41    static sp<DataSource> CreateFromURI(
42            const char *uri,
43            const KeyedVector<String8, String8> *headers = NULL);
44
45    DataSource() {}
46
47    virtual status_t initCheck() const = 0;
48
49    virtual ssize_t readAt(off_t offset, void *data, size_t size) = 0;
50
51    // Convenience methods:
52    bool getUInt16(off_t offset, uint16_t *x);
53
54    // May return ERROR_UNSUPPORTED.
55    virtual status_t getSize(off_t *size);
56
57    virtual uint32_t flags() {
58        return 0;
59    }
60
61    ////////////////////////////////////////////////////////////////////////////
62
63    bool sniff(String8 *mimeType, float *confidence, sp<AMessage> *meta);
64
65    // The sniffer can optionally fill in "meta" with an AMessage containing
66    // a dictionary of values that helps the corresponding extractor initialize
67    // its state without duplicating effort already exerted by the sniffer.
68    typedef bool (*SnifferFunc)(
69            const sp<DataSource> &source, String8 *mimeType,
70            float *confidence, sp<AMessage> *meta);
71
72    static void RegisterSniffer(SnifferFunc func);
73    static void RegisterDefaultSniffers();
74
75protected:
76    virtual ~DataSource() {}
77
78private:
79    static Mutex gSnifferMutex;
80    static List<SnifferFunc> gSniffers;
81
82    DataSource(const DataSource &);
83    DataSource &operator=(const DataSource &);
84};
85
86}  // namespace android
87
88#endif  // DATA_SOURCE_H_
89