1 /* 2 * Copyright (C) 2010 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 /** 18 * @addtogroup Asset 19 * @{ 20 */ 21 22 /** 23 * @file asset_manager.h 24 */ 25 26 #ifndef ANDROID_ASSET_MANAGER_H 27 #define ANDROID_ASSET_MANAGER_H 28 29 #ifdef __cplusplus 30 extern "C" { 31 #endif 32 33 struct AAssetManager; 34 /** 35 * {@link AAssetManager} provides access to an application's raw assets by 36 * creating {@link AAsset} objects. 37 * 38 * AAssetManager is a wrapper to the low-level native implementation 39 * of the java {@link AAssetManager}, a pointer can be obtained using 40 * AAssetManager_fromJava(). 41 * 42 * The asset hierarchy may be examined like a filesystem, using 43 * {@link AAssetDir} objects to peruse a single directory. 44 * 45 * A native {@link AAssetManager} pointer may be shared across multiple threads. 46 */ 47 typedef struct AAssetManager AAssetManager; 48 49 struct AAssetDir; 50 /** 51 * {@link AAssetDir} provides access to a chunk of the asset hierarchy as if 52 * it were a single directory. The contents are populated by the 53 * {@link AAssetManager}. 54 * 55 * The list of files will be sorted in ascending order by ASCII value. 56 */ 57 typedef struct AAssetDir AAssetDir; 58 59 struct AAsset; 60 /** 61 * {@link AAsset} provides access to a read-only asset. 62 * 63 * {@link AAsset} objects are NOT thread-safe, and should not be shared across 64 * threads. 65 */ 66 typedef struct AAsset AAsset; 67 68 /** Available access modes for opening assets with {@link AAssetManager_open} */ 69 enum { 70 /** No specific information about how data will be accessed. **/ 71 AASSET_MODE_UNKNOWN = 0, 72 /** Read chunks, and seek forward and backward. */ 73 AASSET_MODE_RANDOM = 1, 74 /** Read sequentially, with an occasional forward seek. */ 75 AASSET_MODE_STREAMING = 2, 76 /** Caller plans to ask for a read-only buffer with all data. */ 77 AASSET_MODE_BUFFER = 3 78 }; 79 80 81 /** 82 * Open the named directory within the asset hierarchy. The directory can then 83 * be inspected with the AAssetDir functions. To open the top-level directory, 84 * pass in "" as the dirName. 85 * 86 * The object returned here should be freed by calling AAssetDir_close(). 87 */ 88 AAssetDir* AAssetManager_openDir(AAssetManager* mgr, const char* dirName); 89 90 /** 91 * Open an asset. 92 * 93 * The object returned here should be freed by calling AAsset_close(). 94 */ 95 AAsset* AAssetManager_open(AAssetManager* mgr, const char* filename, int mode); 96 97 /** 98 * Iterate over the files in an asset directory. A NULL string is returned 99 * when all the file names have been returned. 100 * 101 * The returned file name is suitable for passing to AAssetManager_open(). 102 * 103 * The string returned here is owned by the AssetDir implementation and is not 104 * guaranteed to remain valid if any other calls are made on this AAssetDir 105 * instance. 106 */ 107 const char* AAssetDir_getNextFileName(AAssetDir* assetDir); 108 109 /** 110 * Reset the iteration state of AAssetDir_getNextFileName() to the beginning. 111 */ 112 void AAssetDir_rewind(AAssetDir* assetDir); 113 114 /** 115 * Close an opened AAssetDir, freeing any related resources. 116 */ 117 void AAssetDir_close(AAssetDir* assetDir); 118 119 /** 120 * Attempt to read 'count' bytes of data from the current offset. 121 * 122 * Returns the number of bytes read, zero on EOF, or < 0 on error. 123 */ 124 int AAsset_read(AAsset* asset, void* buf, size_t count); 125 126 /** 127 * Seek to the specified offset within the asset data. 'whence' uses the 128 * same constants as lseek()/fseek(). 129 * 130 * Returns the new position on success, or (off_t) -1 on error. 131 */ 132 off_t AAsset_seek(AAsset* asset, off_t offset, int whence); 133 134 /** 135 * Seek to the specified offset within the asset data. 'whence' uses the 136 * same constants as lseek()/fseek(). 137 * 138 * Uses 64-bit data type for large files as opposed to the 32-bit type used 139 * by AAsset_seek. 140 * 141 * Returns the new position on success, or (off64_t) -1 on error. 142 */ 143 off64_t AAsset_seek64(AAsset* asset, off64_t offset, int whence); 144 145 /** 146 * Close the asset, freeing all associated resources. 147 */ 148 void AAsset_close(AAsset* asset); 149 150 /** 151 * Get a pointer to a buffer holding the entire contents of the assset. 152 * 153 * Returns NULL on failure. 154 */ 155 const void* AAsset_getBuffer(AAsset* asset); 156 157 /** 158 * Report the total size of the asset data. 159 */ 160 off_t AAsset_getLength(AAsset* asset); 161 162 /** 163 * Report the total size of the asset data. Reports the size using a 64-bit 164 * number insted of 32-bit as AAsset_getLength. 165 */ 166 off64_t AAsset_getLength64(AAsset* asset); 167 168 /** 169 * Report the total amount of asset data that can be read from the current position. 170 */ 171 off_t AAsset_getRemainingLength(AAsset* asset); 172 173 /** 174 * Report the total amount of asset data that can be read from the current position. 175 * 176 * Uses a 64-bit number instead of a 32-bit number as AAsset_getRemainingLength does. 177 */ 178 off64_t AAsset_getRemainingLength64(AAsset* asset); 179 180 /** 181 * Open a new file descriptor that can be used to read the asset data. If the 182 * start or length cannot be represented by a 32-bit number, it will be 183 * truncated. If the file is large, use AAsset_openFileDescriptor64 instead. 184 * 185 * Returns < 0 if direct fd access is not possible (for example, if the asset is 186 * compressed). 187 */ 188 int AAsset_openFileDescriptor(AAsset* asset, off_t* outStart, off_t* outLength); 189 190 /** 191 * Open a new file descriptor that can be used to read the asset data. 192 * 193 * Uses a 64-bit number for the offset and length instead of 32-bit instead of 194 * as AAsset_openFileDescriptor does. 195 * 196 * Returns < 0 if direct fd access is not possible (for example, if the asset is 197 * compressed). 198 */ 199 int AAsset_openFileDescriptor64(AAsset* asset, off64_t* outStart, off64_t* outLength); 200 201 /** 202 * Returns whether this asset's internal buffer is allocated in ordinary RAM (i.e. not 203 * mmapped). 204 */ 205 int AAsset_isAllocated(AAsset* asset); 206 207 208 209 #ifdef __cplusplus 210 }; 211 #endif 212 213 #endif // ANDROID_ASSET_MANAGER_H 214 215 /** @} */ 216