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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 //BEGIN_INCLUDE(all)
19 #include <jni.h>
20 #include <errno.h>
21 
22 #include <EGL/egl.h>
23 #include <GLES/gl.h>
24 
25 #include <android/sensor.h>
26 #include <android/log.h>
27 #include <android_native_app_glue.h>
28 
29 #define LOGI(...) ((void)__android_log_print(ANDROID_LOG_INFO, "native-activity", __VA_ARGS__))
30 #define LOGW(...) ((void)__android_log_print(ANDROID_LOG_WARN, "native-activity", __VA_ARGS__))
31 
32 /**
33  * Our saved state data.
34  */
35 struct saved_state {
36     float angle;
37     int32_t x;
38     int32_t y;
39 };
40 
41 /**
42  * Shared state for our app.
43  */
44 struct engine {
45     struct android_app* app;
46 
47     ASensorManager* sensorManager;
48     const ASensor* accelerometerSensor;
49     ASensorEventQueue* sensorEventQueue;
50 
51     int animating;
52     EGLDisplay display;
53     EGLSurface surface;
54     EGLContext context;
55     int32_t width;
56     int32_t height;
57     struct saved_state state;
58 };
59 
60 /**
61  * Initialize an EGL context for the current display.
62  */
engine_init_display(struct engine * engine)63 static int engine_init_display(struct engine* engine) {
64     // initialize OpenGL ES and EGL
65 
66     /*
67      * Here specify the attributes of the desired configuration.
68      * Below, we select an EGLConfig with at least 8 bits per color
69      * component compatible with on-screen windows
70      */
71     const EGLint attribs[] = {
72             EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
73             EGL_BLUE_SIZE, 8,
74             EGL_GREEN_SIZE, 8,
75             EGL_RED_SIZE, 8,
76             EGL_NONE
77     };
78     EGLint w, h, dummy, format;
79     EGLint numConfigs;
80     EGLConfig config;
81     EGLSurface surface;
82     EGLContext context;
83 
84     EGLDisplay display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
85 
86     eglInitialize(display, 0, 0);
87 
88     /* Here, the application chooses the configuration it desires. In this
89      * sample, we have a very simplified selection process, where we pick
90      * the first EGLConfig that matches our criteria */
91     eglChooseConfig(display, attribs, &config, 1, &numConfigs);
92 
93     /* EGL_NATIVE_VISUAL_ID is an attribute of the EGLConfig that is
94      * guaranteed to be accepted by ANativeWindow_setBuffersGeometry().
95      * As soon as we picked a EGLConfig, we can safely reconfigure the
96      * ANativeWindow buffers to match, using EGL_NATIVE_VISUAL_ID. */
97     eglGetConfigAttrib(display, config, EGL_NATIVE_VISUAL_ID, &format);
98 
99     ANativeWindow_setBuffersGeometry(engine->app->window, 0, 0, format);
100 
101     surface = eglCreateWindowSurface(display, config, engine->app->window, NULL);
102     context = eglCreateContext(display, config, NULL, NULL);
103 
104     if (eglMakeCurrent(display, surface, surface, context) == EGL_FALSE) {
105         LOGW("Unable to eglMakeCurrent");
106         return -1;
107     }
108 
109     eglQuerySurface(display, surface, EGL_WIDTH, &w);
110     eglQuerySurface(display, surface, EGL_HEIGHT, &h);
111 
112     engine->display = display;
113     engine->context = context;
114     engine->surface = surface;
115     engine->width = w;
116     engine->height = h;
117     engine->state.angle = 0;
118 
119     // Initialize GL state.
120     glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_FASTEST);
121     glEnable(GL_CULL_FACE);
122     glShadeModel(GL_SMOOTH);
123     glDisable(GL_DEPTH_TEST);
124 
125     return 0;
126 }
127 
128 /**
129  * Just the current frame in the display.
130  */
engine_draw_frame(struct engine * engine)131 static void engine_draw_frame(struct engine* engine) {
132     if (engine->display == NULL) {
133         // No display.
134         return;
135     }
136 
137     // Just fill the screen with a color.
138     glClearColor(((float)engine->state.x)/engine->width, engine->state.angle,
139             ((float)engine->state.y)/engine->height, 1);
140     glClear(GL_COLOR_BUFFER_BIT);
141 
142     eglSwapBuffers(engine->display, engine->surface);
143 }
144 
145 /**
146  * Tear down the EGL context currently associated with the display.
147  */
engine_term_display(struct engine * engine)148 static void engine_term_display(struct engine* engine) {
149     if (engine->display != EGL_NO_DISPLAY) {
150         eglMakeCurrent(engine->display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
151         if (engine->context != EGL_NO_CONTEXT) {
152             eglDestroyContext(engine->display, engine->context);
153         }
154         if (engine->surface != EGL_NO_SURFACE) {
155             eglDestroySurface(engine->display, engine->surface);
156         }
157         eglTerminate(engine->display);
158     }
159     engine->animating = 0;
160     engine->display = EGL_NO_DISPLAY;
161     engine->context = EGL_NO_CONTEXT;
162     engine->surface = EGL_NO_SURFACE;
163 }
164 
165 /**
166  * Process the next input event.
167  */
engine_handle_input(struct android_app * app,AInputEvent * event)168 static int32_t engine_handle_input(struct android_app* app, AInputEvent* event) {
169     struct engine* engine = (struct engine*)app->userData;
170     if (AInputEvent_getType(event) == AINPUT_EVENT_TYPE_MOTION) {
171         engine->animating = 1;
172         engine->state.x = AMotionEvent_getX(event, 0);
173         engine->state.y = AMotionEvent_getY(event, 0);
174         return 1;
175     }
176     return 0;
177 }
178 
179 /**
180  * Process the next main command.
181  */
engine_handle_cmd(struct android_app * app,int32_t cmd)182 static void engine_handle_cmd(struct android_app* app, int32_t cmd) {
183     struct engine* engine = (struct engine*)app->userData;
184     switch (cmd) {
185         case APP_CMD_SAVE_STATE:
186             // The system has asked us to save our current state.  Do so.
187             engine->app->savedState = malloc(sizeof(struct saved_state));
188             *((struct saved_state*)engine->app->savedState) = engine->state;
189             engine->app->savedStateSize = sizeof(struct saved_state);
190             break;
191         case APP_CMD_INIT_WINDOW:
192             // The window is being shown, get it ready.
193             if (engine->app->window != NULL) {
194                 engine_init_display(engine);
195                 engine_draw_frame(engine);
196             }
197             break;
198         case APP_CMD_TERM_WINDOW:
199             // The window is being hidden or closed, clean it up.
200             engine_term_display(engine);
201             break;
202         case APP_CMD_GAINED_FOCUS:
203             // When our app gains focus, we start monitoring the accelerometer.
204             if (engine->accelerometerSensor != NULL) {
205                 ASensorEventQueue_enableSensor(engine->sensorEventQueue,
206                         engine->accelerometerSensor);
207                 // We'd like to get 60 events per second (in us).
208                 ASensorEventQueue_setEventRate(engine->sensorEventQueue,
209                         engine->accelerometerSensor, (1000L/60)*1000);
210             }
211             break;
212         case APP_CMD_LOST_FOCUS:
213             // When our app loses focus, we stop monitoring the accelerometer.
214             // This is to avoid consuming battery while not being used.
215             if (engine->accelerometerSensor != NULL) {
216                 ASensorEventQueue_disableSensor(engine->sensorEventQueue,
217                         engine->accelerometerSensor);
218             }
219             // Also stop animating.
220             engine->animating = 0;
221             engine_draw_frame(engine);
222             break;
223     }
224 }
225 
226 /**
227  * This is the main entry point of a native application that is using
228  * android_native_app_glue.  It runs in its own thread, with its own
229  * event loop for receiving input events and doing other things.
230  */
android_main(struct android_app * state)231 void android_main(struct android_app* state) {
232     struct engine engine;
233 
234     // Make sure glue isn't stripped.
235     app_dummy();
236 
237     memset(&engine, 0, sizeof(engine));
238     state->userData = &engine;
239     state->onAppCmd = engine_handle_cmd;
240     state->onInputEvent = engine_handle_input;
241     engine.app = state;
242 
243     // Prepare to monitor accelerometer
244     engine.sensorManager = ASensorManager_getInstance();
245     engine.accelerometerSensor = ASensorManager_getDefaultSensor(engine.sensorManager,
246             ASENSOR_TYPE_ACCELEROMETER);
247     engine.sensorEventQueue = ASensorManager_createEventQueue(engine.sensorManager,
248             state->looper, LOOPER_ID_USER, NULL, NULL);
249 
250     if (state->savedState != NULL) {
251         // We are starting with a previous saved state; restore from it.
252         engine.state = *(struct saved_state*)state->savedState;
253     }
254 
255     // loop waiting for stuff to do.
256 
257     while (1) {
258         // Read all pending events.
259         int ident;
260         int events;
261         struct android_poll_source* source;
262 
263         // If not animating, we will block forever waiting for events.
264         // If animating, we loop until all events are read, then continue
265         // to draw the next frame of animation.
266         while ((ident=ALooper_pollAll(engine.animating ? 0 : -1, NULL, &events,
267                 (void**)&source)) >= 0) {
268 
269             // Process this event.
270             if (source != NULL) {
271                 source->process(state, source);
272             }
273 
274             // If a sensor has data, process it now.
275             if (ident == LOOPER_ID_USER) {
276                 if (engine.accelerometerSensor != NULL) {
277                     ASensorEvent event;
278                     while (ASensorEventQueue_getEvents(engine.sensorEventQueue,
279                             &event, 1) > 0) {
280                         LOGI("accelerometer: x=%f y=%f z=%f",
281                                 event.acceleration.x, event.acceleration.y,
282                                 event.acceleration.z);
283                     }
284                 }
285             }
286 
287             // Check if we are exiting.
288             if (state->destroyRequested != 0) {
289                 engine_term_display(&engine);
290                 return;
291             }
292         }
293 
294         if (engine.animating) {
295             // Done with events; draw next animation frame.
296             engine.state.angle += .01f;
297             if (engine.state.angle > 1) {
298                 engine.state.angle = 0;
299             }
300 
301             // Drawing is throttled to the screen update rate, so there
302             // is no need to do timing here.
303             engine_draw_frame(&engine);
304         }
305     }
306 }
307 //END_INCLUDE(all)
308