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 #ifndef _ANDROID_NATIVE_APP_GLUE_H 19 #define _ANDROID_NATIVE_APP_GLUE_H 20 21 #include <poll.h> 22 #include <pthread.h> 23 #include <sched.h> 24 25 #include <android/configuration.h> 26 #include <android/looper.h> 27 #include <android/native_activity.h> 28 29 #ifdef __cplusplus 30 extern "C" { 31 #endif 32 33 /** 34 * The native activity interface provided by <android/native_activity.h> 35 * is based on a set of application-provided callbacks that will be called 36 * by the Activity's main thread when certain events occur. 37 * 38 * This means that each one of this callbacks _should_ _not_ block, or they 39 * risk having the system force-close the application. This programming 40 * model is direct, lightweight, but constraining. 41 * 42 * The 'threaded_native_app' static library is used to provide a different 43 * execution model where the application can implement its own main event 44 * loop in a different thread instead. Here's how it works: 45 * 46 * 1/ The application must provide a function named "android_main()" that 47 * will be called when the activity is created, in a new thread that is 48 * distinct from the activity's main thread. 49 * 50 * 2/ android_main() receives a pointer to a valid "android_app" structure 51 * that contains references to other important objects, e.g. the 52 * ANativeActivity obejct instance the application is running in. 53 * 54 * 3/ the "android_app" object holds an ALooper instance that already 55 * listens to two important things: 56 * 57 * - activity lifecycle events (e.g. "pause", "resume"). See APP_CMD_XXX 58 * declarations below. 59 * 60 * - input events coming from the AInputQueue attached to the activity. 61 * 62 * Each of these correspond to an ALooper identifier returned by 63 * ALooper_pollOnce with values of LOOPER_ID_MAIN and LOOPER_ID_INPUT, 64 * respectively. 65 * 66 * Your application can use the same ALooper to listen to additional 67 * file-descriptors. They can either be callback based, or with return 68 * identifiers starting with LOOPER_ID_USER. 69 * 70 * 4/ Whenever you receive a LOOPER_ID_MAIN or LOOPER_ID_INPUT event, 71 * the returned data will point to an android_poll_source structure. You 72 * can call the process() function on it, and fill in android_app->onAppCmd 73 * and android_app->onInputEvent to be called for your own processing 74 * of the event. 75 * 76 * Alternatively, you can call the low-level functions to read and process 77 * the data directly... look at the process_cmd() and process_input() 78 * implementations in the glue to see how to do this. 79 * 80 * See the sample named "native-activity" that comes with the NDK with a 81 * full usage example. Also look at the JavaDoc of NativeActivity. 82 */ 83 84 struct android_app; 85 86 /** 87 * Data associated with an ALooper fd that will be returned as the "outData" 88 * when that source has data ready. 89 */ 90 struct android_poll_source { 91 // The identifier of this source. May be LOOPER_ID_MAIN or 92 // LOOPER_ID_INPUT. 93 int32_t id; 94 95 // The android_app this ident is associated with. 96 struct android_app* app; 97 98 // Function to call to perform the standard processing of data from 99 // this source. 100 void (*process)(struct android_app* app, struct android_poll_source* source); 101 }; 102 103 /** 104 * This is the interface for the standard glue code of a threaded 105 * application. In this model, the application's code is running 106 * in its own thread separate from the main thread of the process. 107 * It is not required that this thread be associated with the Java 108 * VM, although it will need to be in order to make JNI calls any 109 * Java objects. 110 */ 111 struct android_app { 112 // The application can place a pointer to its own state object 113 // here if it likes. 114 void* userData; 115 116 // Fill this in with the function to process main app commands (APP_CMD_*) 117 void (*onAppCmd)(struct android_app* app, int32_t cmd); 118 119 // Fill this in with the function to process input events. At this point 120 // the event has already been pre-dispatched, and it will be finished upon 121 // return. Return 1 if you have handled the event, 0 for any default 122 // dispatching. 123 int32_t (*onInputEvent)(struct android_app* app, AInputEvent* event); 124 125 // The ANativeActivity object instance that this app is running in. 126 ANativeActivity* activity; 127 128 // The current configuration the app is running in. 129 AConfiguration* config; 130 131 // This is the last instance's saved state, as provided at creation time. 132 // It is NULL if there was no state. You can use this as you need; the 133 // memory will remain around until you call android_app_exec_cmd() for 134 // APP_CMD_RESUME, at which point it will be freed and savedState set to NULL. 135 // These variables should only be changed when processing a APP_CMD_SAVE_STATE, 136 // at which point they will be initialized to NULL and you can malloc your 137 // state and place the information here. In that case the memory will be 138 // freed for you later. 139 void* savedState; 140 size_t savedStateSize; 141 142 // The ALooper associated with the app's thread. 143 ALooper* looper; 144 145 // When non-NULL, this is the input queue from which the app will 146 // receive user input events. 147 AInputQueue* inputQueue; 148 149 // When non-NULL, this is the window surface that the app can draw in. 150 ANativeWindow* window; 151 152 // Current content rectangle of the window; this is the area where the 153 // window's content should be placed to be seen by the user. 154 ARect contentRect; 155 156 // Current state of the app's activity. May be either APP_CMD_START, 157 // APP_CMD_RESUME, APP_CMD_PAUSE, or APP_CMD_STOP; see below. 158 int activityState; 159 160 // This is non-zero when the application's NativeActivity is being 161 // destroyed and waiting for the app thread to complete. 162 int destroyRequested; 163 164 // ------------------------------------------------- 165 // Below are "private" implementation of the glue code. 166 167 pthread_mutex_t mutex; 168 pthread_cond_t cond; 169 170 int msgread; 171 int msgwrite; 172 173 pthread_t thread; 174 175 struct android_poll_source cmdPollSource; 176 struct android_poll_source inputPollSource; 177 178 int running; 179 int stateSaved; 180 int destroyed; 181 int redrawNeeded; 182 AInputQueue* pendingInputQueue; 183 ANativeWindow* pendingWindow; 184 ARect pendingContentRect; 185 }; 186 187 enum { 188 /** 189 * Looper data ID of commands coming from the app's main thread, which 190 * is returned as an identifier from ALooper_pollOnce(). The data for this 191 * identifier is a pointer to an android_poll_source structure. 192 * These can be retrieved and processed with android_app_read_cmd() 193 * and android_app_exec_cmd(). 194 */ 195 LOOPER_ID_MAIN = 1, 196 197 /** 198 * Looper data ID of events coming from the AInputQueue of the 199 * application's window, which is returned as an identifier from 200 * ALooper_pollOnce(). The data for this identifier is a pointer to an 201 * android_poll_source structure. These can be read via the inputQueue 202 * object of android_app. 203 */ 204 LOOPER_ID_INPUT = 2, 205 206 /** 207 * Start of user-defined ALooper identifiers. 208 */ 209 LOOPER_ID_USER = 3, 210 }; 211 212 enum { 213 /** 214 * Command from main thread: the AInputQueue has changed. Upon processing 215 * this command, android_app->inputQueue will be updated to the new queue 216 * (or NULL). 217 */ 218 APP_CMD_INPUT_CHANGED, 219 220 /** 221 * Command from main thread: a new ANativeWindow is ready for use. Upon 222 * receiving this command, android_app->window will contain the new window 223 * surface. 224 */ 225 APP_CMD_INIT_WINDOW, 226 227 /** 228 * Command from main thread: the existing ANativeWindow needs to be 229 * terminated. Upon receiving this command, android_app->window still 230 * contains the existing window; after calling android_app_exec_cmd 231 * it will be set to NULL. 232 */ 233 APP_CMD_TERM_WINDOW, 234 235 /** 236 * Command from main thread: the current ANativeWindow has been resized. 237 * Please redraw with its new size. 238 */ 239 APP_CMD_WINDOW_RESIZED, 240 241 /** 242 * Command from main thread: the system needs that the current ANativeWindow 243 * be redrawn. You should redraw the window before handing this to 244 * android_app_exec_cmd() in order to avoid transient drawing glitches. 245 */ 246 APP_CMD_WINDOW_REDRAW_NEEDED, 247 248 /** 249 * Command from main thread: the content area of the window has changed, 250 * such as from the soft input window being shown or hidden. You can 251 * find the new content rect in android_app::contentRect. 252 */ 253 APP_CMD_CONTENT_RECT_CHANGED, 254 255 /** 256 * Command from main thread: the app's activity window has gained 257 * input focus. 258 */ 259 APP_CMD_GAINED_FOCUS, 260 261 /** 262 * Command from main thread: the app's activity window has lost 263 * input focus. 264 */ 265 APP_CMD_LOST_FOCUS, 266 267 /** 268 * Command from main thread: the current device configuration has changed. 269 */ 270 APP_CMD_CONFIG_CHANGED, 271 272 /** 273 * Command from main thread: the system is running low on memory. 274 * Try to reduce your memory use. 275 */ 276 APP_CMD_LOW_MEMORY, 277 278 /** 279 * Command from main thread: the app's activity has been started. 280 */ 281 APP_CMD_START, 282 283 /** 284 * Command from main thread: the app's activity has been resumed. 285 */ 286 APP_CMD_RESUME, 287 288 /** 289 * Command from main thread: the app should generate a new saved state 290 * for itself, to restore from later if needed. If you have saved state, 291 * allocate it with malloc and place it in android_app.savedState with 292 * the size in android_app.savedStateSize. The will be freed for you 293 * later. 294 */ 295 APP_CMD_SAVE_STATE, 296 297 /** 298 * Command from main thread: the app's activity has been paused. 299 */ 300 APP_CMD_PAUSE, 301 302 /** 303 * Command from main thread: the app's activity has been stopped. 304 */ 305 APP_CMD_STOP, 306 307 /** 308 * Command from main thread: the app's activity is being destroyed, 309 * and waiting for the app thread to clean up and exit before proceeding. 310 */ 311 APP_CMD_DESTROY, 312 }; 313 314 /** 315 * Call when ALooper_pollAll() returns LOOPER_ID_MAIN, reading the next 316 * app command message. 317 */ 318 int8_t android_app_read_cmd(struct android_app* android_app); 319 320 /** 321 * Call with the command returned by android_app_read_cmd() to do the 322 * initial pre-processing of the given command. You can perform your own 323 * actions for the command after calling this function. 324 */ 325 void android_app_pre_exec_cmd(struct android_app* android_app, int8_t cmd); 326 327 /** 328 * Call with the command returned by android_app_read_cmd() to do the 329 * final post-processing of the given command. You must have done your own 330 * actions for the command before calling this function. 331 */ 332 void android_app_post_exec_cmd(struct android_app* android_app, int8_t cmd); 333 334 /** 335 * Dummy function you can call to ensure glue code isn't stripped. 336 */ 337 void app_dummy(); 338 339 /** 340 * This is the function that application code must implement, representing 341 * the main entry to the app. 342 */ 343 extern void android_main(struct android_app* app); 344 345 #ifdef __cplusplus 346 } 347 #endif 348 349 #endif /* _ANDROID_NATIVE_APP_GLUE_H */ 350