From 85448bbecd4e0909eecfab15b7c3605f114d0427 Mon Sep 17 00:00:00 2001 From: Dianne Hackborn Date: Wed, 7 Jul 2010 14:27:31 -0700 Subject: Add new glue code for writing native apps. This factors out the boiler-plate code from the sample app to a common glue code that can be used for everyone writing this style of app: a dedicated app thread that takes care of waiting for events and processing them. As part of doing this, ALooper has a new facility to allow registration of fds that cause ALooper_pollOnce() to return the fd that has data, allowing the app to drive the loop without callbacks. Hopefully this makes some people feel better. :) Also do some other cleanup of the ALooper API, plus some actual documentation. Change-Id: Ic53bd56bdf627e3ba28a3c093faa06a92be522b8 --- native/include/android/input.h | 5 +- native/include/android/looper.h | 134 ++++++++++++++++++++++- native/include/android_glue/threaded_app.h | 168 +++++++++++++++++++++++++++++ 3 files changed, 301 insertions(+), 6 deletions(-) create mode 100644 native/include/android_glue/threaded_app.h (limited to 'native/include') diff --git a/native/include/android/input.h b/native/include/android/input.h index 75be85a..014b6a3 100644 --- a/native/include/android/input.h +++ b/native/include/android/input.h @@ -534,10 +534,11 @@ struct AInputQueue; typedef struct AInputQueue AInputQueue; /* - * Add this input queue to a looper for processing. + * Add this input queue to a looper for processing. See + * ALooper_addFd() for information on the callback and data params. */ void AInputQueue_attachLooper(AInputQueue* queue, ALooper* looper, - ALooper_callbackFunc callback, void* data); + ALooper_callbackFunc* callback, void* data); /* * Remove the input queue from the looper it is currently attached to. diff --git a/native/include/android/looper.h b/native/include/android/looper.h index 90a8983..2917216 100644 --- a/native/include/android/looper.h +++ b/native/include/android/looper.h @@ -24,25 +24,151 @@ extern "C" { #endif +/** + * ALooper + * + * A looper is the state tracking an event loop for a thread. + * Loopers do not define event structures or other such things; rather + * they are a lower-level facility to attach one or more discrete objects + * listening for an event. An "event" here is simply data available on + * a file descriptor: each attached object has an associated file descriptor, + * and waiting for "events" means (internally) polling on all of these file + * descriptors until one or more of them have data available. + * + * A thread can have only one ALooper associated with it. + */ struct ALooper; typedef struct ALooper ALooper; +/** + * For callback-based event loops, this is the prototype of the function + * that is called. It is given the file descriptor it is associated with, + * a bitmask of the poll events that were triggered (typically POLLIN), and + * the data pointer that was originally supplied. + * + * Implementations should return 1 to continue receiving callbacks, or 0 + * to have this file descriptor and callback unregistered from the looper. + */ typedef int ALooper_callbackFunc(int fd, int events, void* data); +/** + * Return the ALooper associated with the calling thread, or NULL if + * there is not one. + */ ALooper* ALooper_forThread(); -ALooper* ALooper_prepare(); +enum { + /** + * Option for ALooper_prepare: this ALooper will accept calls to + * ALooper_addFd() that do not have a callback (that is provide NULL + * for the callback). In this case the caller of ALooper_pollOnce() + * or ALooper_pollAll() MUST check the return from these functions to + * discover when data is available on such fds and process it. + */ + ALOOPER_PREPARE_ALLOW_NON_CALLBACKS = 1<<0 +}; -int32_t ALooper_pollOnce(int timeoutMillis); +/** + * Prepare an ALooper associated with the calling thread, and return it. + * If the thread already has an ALooper, it is returned. Otherwise, a new + * one is created, associated with the thread, and returned. + * + * The opts may be ALOOPER_PREPARE_ALLOW_NON_CALLBACKS or 0. + */ +ALooper* ALooper_prepare(int32_t opts); + +enum { + /** + * Result from ALooper_pollOnce() and ALooper_pollAll(): one or + * more callbacks were executed. + */ + ALOOPER_POLL_CALLBACK = -1, + + /** + * Result from ALooper_pollOnce() and ALooper_pollAll(): the + * timeout expired. + */ + ALOOPER_POLL_TIMEOUT = -2, + + /** + * Result from ALooper_pollOnce() and ALooper_pollAll(): an error + * occurred. + */ + ALOOPER_POLL_ERROR = -3, +}; +/** + * Wait for events to be available, with optional timeout in milliseconds. + * Invokes callbacks for all file descriptors on which an event occurred. + * + * If the timeout is zero, returns immediately without blocking. + * If the timeout is negative, waits indefinitely until an event appears. + * + * Returns ALOOPER_POLL_CALLBACK if a callback was invoked. + * + * Returns ALOOPER_POLL_TIMEOUT if there was no data before the given + * timeout expired. + * + * Returns ALOPER_POLL_ERROR if an error occurred. + * + * Returns a value >= 0 containing a file descriptor if it has data + * and it has no callback function (requiring the caller here to handle it). + * In this (and only this) case outEvents and outData will contain the poll + * events and data associated with the fd. + * + * This method does not return until it has finished invoking the appropriate callbacks + * for all file descriptors that were signalled. + */ +int32_t ALooper_pollOnce(int timeoutMillis, int* outEvents, void** outData); + +/** + * Like ALooper_pollOnce(), but performs all pending callbacks until all + * data has been consumed or a file descriptor is available with no callback. + * This function will never return ALOOPER_POLL_CALLBACK. + */ +int32_t ALooper_pollAll(int timeoutMillis, int* outEvents, void** outData); + +/** + * Acquire a reference on the given ALooper object. This prevents the object + * from being deleted until the reference is removed. This is only needed + * to safely hand an ALooper from one thread to another. + */ void ALooper_acquire(ALooper* looper); +/** + * Remove a reference that was previously acquired with ALooper_acquire(). + */ void ALooper_release(ALooper* looper); -void ALooper_setCallback(ALooper* looper, int fd, int events, +/** + * Add a new file descriptor to be polled by the looper. If the same file + * descriptor was previously added, it is replaced. + * + * "fd" is the file descriptor to be added. + * "events" are the poll events to wake up on. Typically this is POLLIN. + * "callback" is the function to call when there is an event on the file + * descriptor. + * "id" is an identifier to associated with this file descriptor, or 0. + * "data" is a private data pointer to supply to the callback. + * + * There are two main uses of this function: + * + * (1) If "callback" is non-NULL, then + * this function will be called when there is data on the file descriptor. It + * should execute any events it has pending, appropriately reading from the + * file descriptor. + * + * (2) If "callback" is NULL, the fd will be returned by ALooper_pollOnce + * when it has data available, requiring the caller to take care of processing + * it. + */ +void ALooper_addFd(ALooper* looper, int fd, int events, ALooper_callbackFunc* callback, void* data); -int32_t ALooper_removeCallback(ALooper* looper, int fd); +/** + * Remove a previously added file descriptor from the looper. + */ +int32_t ALooper_removeFd(ALooper* looper, int fd); #ifdef __cplusplus }; diff --git a/native/include/android_glue/threaded_app.h b/native/include/android_glue/threaded_app.h new file mode 100644 index 0000000..80de3bf --- /dev/null +++ b/native/include/android_glue/threaded_app.h @@ -0,0 +1,168 @@ +/* + * Copyright (C) 2010 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 + * + * http://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. + * + */ + +#include +#include +#include + +#include +#include + +/** + * This is the interface for the standard glue code of a threaded + * application. In this model, the application's code is running + * in its own thread separate from the main thread of the process. + * It is not required that this thread be associated with the Java + * VM, although it will need to be in order to make JNI calls any + * Java objects. + */ +struct android_app { + // The application can place a pointer to its own state object + // here if it likes. + void* userData; + + // The ANativeActivity object instance that this app is running in. + ANativeActivity* activity; + + // The ALooper associated with the app's thread. + ALooper* looper; + + // When non-NULL, this is the input queue from which the app will + // receive user input events. + AInputQueue* inputQueue; + + // When non-NULL, this is the window surface that the app can draw in. + ANativeWindow* window; + + // Current state of the app's activity. May be either APP_CMD_START, + // APP_CMD_RESUME, APP_CMD_PAUSE, or APP_CMD_STOP; see below. + int activityState; + + // This is non-zero when the application's NativeActivity is being + // destroyed and waiting for the app thread to complete. + int destroyRequested; + + // ------------------------------------------------- + // Below are "private" implementation of the glue code. + + pthread_mutex_t mutex; + pthread_cond_t cond; + + int msgread; + int msgwrite; + + pthread_t thread; + + int running; + int destroyed; + AInputQueue* pendingInputQueue; + ANativeWindow* pendingWindow; +}; + +enum { + /** + * Looper data ID of commands coming from the app's main thread. + * These can be retrieved and processed with android_app_read_cmd() + * and android_app_exec_cmd(). + */ + LOOPER_ID_MAIN = 1, + + /** + * Looper data ID of events coming from the AInputQueue of the + * application's window. These can be read via the inputQueue + * object of android_app. + */ + LOOPER_ID_EVENT = 2 +}; + +enum { + /** + * Command from main thread: the AInputQueue has changed. Upon processing + * this command, android_app->inputQueue will be updated to the new queue + * (or NULL). + */ + APP_CMD_INPUT_CHANGED, + + /** + * Command from main thread: the ANativeWindow has changed. Upon processing + * this command, android_app->window will be updated to the new window surface + * (or NULL). + */ + APP_CMD_WINDOW_CHANGED, + + /** + * Command from main thread: the app's activity window has gained + * input focus. + */ + APP_CMD_GAINED_FOCUS, + + /** + * Command from main thread: the app's activity window has lost + * input focus. + */ + APP_CMD_LOST_FOCUS, + + /** + * Command from main thread: the app's activity has been started. + */ + APP_CMD_START, + + /** + * Command from main thread: the app's activity has been resumed. + */ + APP_CMD_RESUME, + + /** + * Command from main thread: the app's activity has been paused. + */ + APP_CMD_PAUSE, + + /** + * Command from main thread: the app's activity has been stopped. + */ + APP_CMD_STOP, + + /** + * Command from main thread: the app's activity is being destroyed, + * and waiting for the app thread to clean up and exit before proceeding. + */ + APP_CMD_DESTROY, +}; + +/** + * Call if android_app->destroyRequested is non-zero. Upon return, the + * android_app structure is no longer valid and must not be touched. + */ +void android_app_destroy(struct android_app* android_app); + +/** + * Call when ALooper_pollAll() returns LOOPER_ID_MAIN, reading the next + * app command message. + */ +int8_t android_app_read_cmd(struct android_app* android_app); + +/** + * Call with the command returned by android_app_read_cmd() to do the + * default processing of the given command. + */ +void android_app_exec_cmd(struct android_app* android_app, int8_t cmd); + +/** + * This is the function that application code must implement, representing + * the main entry to the app. + */ +extern void android_main(struct android_app* app); -- cgit v1.1