bgfx/3rdparty/native_app_glue/android_native_app_glue.h

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/*
* 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.
*/
#pragma once
#include <poll.h>
#include <pthread.h>
#include <sched.h>
#include <android/configuration.h>
#include <android/looper.h>
#include <android/native_activity.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* The native activity interface provided by <android/native_activity.h>
* is based on a set of application-provided callbacks that will be called
* by the Activity's main thread when certain events occur.
*
* This means that each one of this callbacks _should_ _not_ block, or they
* risk having the system force-close the application. This programming
* model is direct, lightweight, but constraining.
*
* The 'android_native_app_glue' static library is used to provide a different
* execution model where the application can implement its own main event
* loop in a different thread instead. Here's how it works:
*
* 1/ The application must provide a function named "android_main()" that
* will be called when the activity is created, in a new thread that is
* distinct from the activity's main thread.
*
* 2/ android_main() receives a pointer to a valid "android_app" structure
* that contains references to other important objects, e.g. the
* ANativeActivity obejct instance the application is running in.
*
* 3/ the "android_app" object holds an ALooper instance that already
* listens to two important things:
*
* - activity lifecycle events (e.g. "pause", "resume"). See APP_CMD_XXX
* declarations below.
*
* - input events coming from the AInputQueue attached to the activity.
*
* Each of these correspond to an ALooper identifier returned by
* ALooper_pollOnce with values of LOOPER_ID_MAIN and LOOPER_ID_INPUT,
* respectively.
*
* Your application can use the same ALooper to listen to additional
* file-descriptors. They can either be callback based, or with return
* identifiers starting with LOOPER_ID_USER.
*
* 4/ Whenever you receive a LOOPER_ID_MAIN or LOOPER_ID_INPUT event,
* the returned data will point to an android_poll_source structure. You
* can call the process() function on it, and fill in android_app->onAppCmd
* and android_app->onInputEvent to be called for your own processing
* of the event.
*
* Alternatively, you can call the low-level functions to read and process
* the data directly... look at the process_cmd() and process_input()
* implementations in the glue to see how to do this.
*
* See the sample named "native-activity" that comes with the NDK with a
* full usage example. Also look at the JavaDoc of NativeActivity.
*/
struct android_app;
/**
* Data associated with an ALooper fd that will be returned as the "outData"
* when that source has data ready.
*/
struct android_poll_source {
// The identifier of this source. May be LOOPER_ID_MAIN or
// LOOPER_ID_INPUT.
int32_t id;
// The android_app this ident is associated with.
struct android_app* app;
// Function to call to perform the standard processing of data from
// this source.
void (*process)(struct android_app* app, struct android_poll_source* source);
};
/**
* 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;
// Fill this in with the function to process main app commands (APP_CMD_*)
void (*onAppCmd)(struct android_app* app, int32_t cmd);
// Fill this in with the function to process input events. At this point
// the event has already been pre-dispatched, and it will be finished upon
// return. Return 1 if you have handled the event, 0 for any default
// dispatching.
int32_t (*onInputEvent)(struct android_app* app, AInputEvent* event);
// The ANativeActivity object instance that this app is running in.
ANativeActivity* activity;
// The current configuration the app is running in.
AConfiguration* config;
// This is the last instance's saved state, as provided at creation time.
// It is NULL if there was no state. You can use this as you need; the
// memory will remain around until you call android_app_exec_cmd() for
// APP_CMD_RESUME, at which point it will be freed and savedState set to NULL.
// These variables should only be changed when processing a APP_CMD_SAVE_STATE,
// at which point they will be initialized to NULL and you can malloc your
// state and place the information here. In that case the memory will be
// freed for you later.
void* savedState;
size_t savedStateSize;
// 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 content rectangle of the window; this is the area where the
// window's content should be placed to be seen by the user.
ARect contentRect;
// 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;
struct android_poll_source cmdPollSource;
struct android_poll_source inputPollSource;
int running;
int stateSaved;
int destroyed;
int redrawNeeded;
AInputQueue* pendingInputQueue;
ANativeWindow* pendingWindow;
ARect pendingContentRect;
};
enum {
/**
* Looper data ID of commands coming from the app's main thread, which
* is returned as an identifier from ALooper_pollOnce(). The data for this
* identifier is a pointer to an android_poll_source structure.
* 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, which is returned as an identifier from
* ALooper_pollOnce(). The data for this identifier is a pointer to an
* android_poll_source structure. These can be read via the inputQueue
* object of android_app.
*/
LOOPER_ID_INPUT = 2,
/**
* Start of user-defined ALooper identifiers.
*/
LOOPER_ID_USER = 3,
};
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: a new ANativeWindow is ready for use. Upon
* receiving this command, android_app->window will contain the new window
* surface.
*/
APP_CMD_INIT_WINDOW,
/**
* Command from main thread: the existing ANativeWindow needs to be
* terminated. Upon receiving this command, android_app->window still
* contains the existing window; after calling android_app_exec_cmd
* it will be set to NULL.
*/
APP_CMD_TERM_WINDOW,
/**
* Command from main thread: the current ANativeWindow has been resized.
* Please redraw with its new size.
*/
APP_CMD_WINDOW_RESIZED,
/**
* Command from main thread: the system needs that the current ANativeWindow
* be redrawn. You should redraw the window before handing this to
* android_app_exec_cmd() in order to avoid transient drawing glitches.
*/
APP_CMD_WINDOW_REDRAW_NEEDED,
/**
* Command from main thread: the content area of the window has changed,
* such as from the soft input window being shown or hidden. You can
* find the new content rect in android_app::contentRect.
*/
APP_CMD_CONTENT_RECT_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 current device configuration has changed.
*/
APP_CMD_CONFIG_CHANGED,
/**
* Command from main thread: the system is running low on memory.
* Try to reduce your memory use.
*/
APP_CMD_LOW_MEMORY,
/**
* 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 should generate a new saved state
* for itself, to restore from later if needed. If you have saved state,
* allocate it with malloc and place it in android_app.savedState with
* the size in android_app.savedStateSize. The will be freed for you
* later.
*/
APP_CMD_SAVE_STATE,
/**
* 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 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
* initial pre-processing of the given command. You can perform your own
* actions for the command after calling this function.
*/
void android_app_pre_exec_cmd(struct android_app* android_app, int8_t cmd);
/**
* Call with the command returned by android_app_read_cmd() to do the
* final post-processing of the given command. You must have done your own
* actions for the command before calling this function.
*/
void android_app_post_exec_cmd(struct android_app* android_app, int8_t cmd);
/**
* No-op function that used to be used to prevent the linker from stripping app
* glue code. No longer necessary, since __attribute__((visibility("default")))
* does this for us.
*/
__attribute__((
deprecated("Calls to app_dummy are no longer necessary. See "
"https://github.com/android-ndk/ndk/issues/381."))) void
app_dummy();
/**
* This is the function that application code must implement, representing
* the main entry to the app.
*/
extern void android_main(struct android_app* app);
#ifdef __cplusplus
}
#endif