Android-NDK处理用户交互事件

在 android_main（struct android_app* state)函数里面设置输入事件处理函数：
state->onInputEvent = &handleInput;//设置输入事件的处理函数，如触摸响应

函数介绍:

AMotionEvent_getX():以屏幕左上角为原点,是绝对坐标

AMotionEvent_getY():以屏幕左上角为原点,是绝对坐标

AMotionEvent_getPointerCount();多点触摸函数，返回触摸的点数量，跟硬件有关系

#include <jni.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>


#include <EGL/egl.h>
#include <GLES/gl.h>
#include <vector>
#include <string>
#include <map>
#include <android/sensor.h>
#include <android/log.h>
#include <android_native_app_glue.h>

#define LOGI(...) ((void)__android_log_print(ANDROID_LOG_ERROR, "native-activity", __VA_ARGS__))
#define LOGW(...) ((void)__android_log_print(ANDROID_LOG_WARN, "native-activity", __VA_ARGS__))

/**
 * Our saved state data.
 */
struct saved_state {
    float angle;
    int32_t x;
    int32_t y;
};

/**
 * Shared state for our app.
 */
struct engine {
    struct android_app* app;

    ASensorManager* sensorManager;
    const ASensor* accelerometerSensor;
    ASensorEventQueue* sensorEventQueue;

    int         animating;
    EGLDisplay     display;
    EGLSurface     surface;
    EGLContext     context;
    int32_t     width;
    int32_t     height;
    struct saved_state state;
};

class float3
{
public:
    float x,y,z;
};
std::vector<float3> g_arVertex;
/**
 * Initialize an EGL context for the current display.
 */
static int engine_init_display(struct engine* engine) {
    // initialize OpenGL ES and EGL

    /*
     * Here specify the attributes of the desired configuration.
     * Below, we select an EGLConfig with at least 8 bits per color
     * component compatible with on-screen windows
     */
    const EGLint attribs[] =
    {
            EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
            EGL_BLUE_SIZE, 8,
            EGL_GREEN_SIZE, 8,
            EGL_RED_SIZE, 8,
            EGL_NONE
    };
    EGLint w, h, dummy, format;
    EGLint         numConfigs;
    EGLConfig     config;
    EGLSurface     surface;
    EGLContext     context;

    EGLDisplay     display = eglGetDisplay(EGL_DEFAULT_DISPLAY);

    eglInitialize(display, 0, 0);

    /* Here, the application chooses the configuration it desires. In this
     * sample, we have a very simplified selection process, where we pick
     * the first EGLConfig that matches our criteria */
    eglChooseConfig(display, attribs, &config, 1, &numConfigs);

    /* EGL_NATIVE_VISUAL_ID is an attribute of the EGLConfig that is
     * guaranteed to be accepted by ANativeWindow_setBuffersGeometry().
     * As soon as we picked a EGLConfig, we can safely reconfigure the
     * ANativeWindow buffers to match, using EGL_NATIVE_VISUAL_ID. */
    eglGetConfigAttrib(display, config, EGL_NATIVE_VISUAL_ID, &format);

    ANativeWindow_setBuffersGeometry(engine->app->window, 0, 0, format);

    surface = eglCreateWindowSurface(display, config, engine->app->window, NULL);
    context = eglCreateContext(display, config, NULL, NULL);

    if (eglMakeCurrent(display, surface, surface, context) == EGL_FALSE) {
        LOGW("Unable to eglMakeCurrent");
        return -1;
    }

    eglQuerySurface(display, surface, EGL_WIDTH, &w);
    eglQuerySurface(display, surface, EGL_HEIGHT, &h);

    engine->display     = display;
    engine->context     = context;
    engine->surface     = surface;
    engine->width         = w;
    engine->height         = h;
    engine->state.angle = 0;

    // Initialize GL state.
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_FASTEST);
    glEnable(GL_CULL_FACE);
    glShadeModel(GL_SMOOTH);
    glDisable(GL_DEPTH_TEST);
    glViewport(0,0,w,h);
    glOrthof(0,w,h,0,-100,100);

    return 0;
}

/**
 * Just the current frame in the display.
 */
static void engine_draw_frame(struct engine* engine) {
    if (engine->display == NULL) {
        // No display.
        return;
    }

    // Just fill the screen with a color.
    glClearColor(((float)engine->state.x)/engine->width, engine->state.angle,
            ((float)engine->state.y)/engine->height, 1);
    glClear(GL_COLOR_BUFFER_BIT);


    glEnableClientState(GL_VERTEX_ARRAY);
    if(g_arVertex.size() >= 2)
    {
        glColor4f(1,1,1,1);
        glVertexPointer(3,GL_FLOAT,0,&g_arVertex[0]);
        glDrawArrays(GL_LINE_STRIP,0,g_arVertex.size());
    }


    eglSwapBuffers(engine->display, engine->surface);
}

/**
 * Tear down the EGL context currently associated with the display.
 */
static void engine_term_display(struct engine* engine) {
    if (engine->display != EGL_NO_DISPLAY) {
        eglMakeCurrent(engine->display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
        if (engine->context != EGL_NO_CONTEXT) {
            eglDestroyContext(engine->display, engine->context);
        }
        if (engine->surface != EGL_NO_SURFACE) {
            eglDestroySurface(engine->display, engine->surface);
        }
        eglTerminate(engine->display);
    }
    engine->animating = 0;
    engine->display = EGL_NO_DISPLAY;
    engine->context = EGL_NO_CONTEXT;
    engine->surface = EGL_NO_SURFACE;
}

/**
 * Process the next input event.
 */
static int32_t engine_handle_input(struct android_app* app, AInputEvent* event)
{
    struct engine* engine = (struct engine*)app->userData;


    int32_t    evtType    =    AInputEvent_getType(event);
    switch(evtType)
    {
    case AINPUT_EVENT_TYPE_KEY:
        break;

    case AINPUT_EVENT_TYPE_MOTION:
        {
            switch(AInputEvent_getSource(event))
            {
            case AINPUT_SOURCE_TOUCHSCREEN:
                {
                    int32_t id = AMotionEvent_getAction(event);
                    switch(id)
                    {
                    case AMOTION_EVENT_ACTION_MOVE:
                        {
                            size_t    cnt = AMotionEvent_getPointerCount(event);
                            for( int i = 0 ;i < cnt; ++ i )
                            {
                                float x = AMotionEvent_getX(event,i);
                                float y = AMotionEvent_getY(event,i);
                                char  szBuf[64];
                                LOGI("x = %f   y = %f",x,y);
                                float3 pt;
                                pt.x = x;
                                pt.y = y;
                                pt.z = 0;
                                g_arVertex.push_back(pt);
                            }

                        }
                        break;
                    case AMOTION_EVENT_ACTION_DOWN:
                        {
                            float x = AMotionEvent_getX(event,0);
                            float y = AMotionEvent_getY(event,0);
                            char  szBuf[64];
                            LOGI("x = %f   y = %f",x,y);
                            float3 pt;
                            pt.x = x;
                            pt.y = y;
                            pt.z = 0;
                            g_arVertex.push_back(pt);
                        }
                        break;
                    case AMOTION_EVENT_ACTION_UP:
                        break;
                    }
                }
                break;
            case AINPUT_SOURCE_TRACKBALL:
                break;
            }
        }
        break;
    }


    if (AInputEvent_getType(event) == AINPUT_EVENT_TYPE_MOTION)
    {
        engine->animating = 1;
        engine->state.x = AMotionEvent_getX(event, 0);
        engine->state.y = AMotionEvent_getY(event, 0);
        return 1;
    }
    return 0;
}

/**
 * Process the next main command.
 */
static void engine_handle_cmd(struct android_app* app, int32_t cmd) {
    struct engine* engine = (struct engine*)app->userData;
    switch (cmd) {
        case APP_CMD_SAVE_STATE:

            break;
        case APP_CMD_INIT_WINDOW:
            // The window is being shown, get it ready.
            if (engine->app->window != NULL) {
                engine_init_display(engine);
            }
            break;
        case APP_CMD_TERM_WINDOW:
            // The window is being hidden or closed, clean it up.
            engine_term_display(engine);
            break;
        case APP_CMD_GAINED_FOCUS:

            break;
        case APP_CMD_LOST_FOCUS:

            break;
    }
}

/**
 * This is the main entry point of a native application that is using
 * android_native_app_glue.  It runs in its own thread, with its own
 * event loop for receiving input events and doing other things.
 */
void android_main(struct android_app* state) {
    struct engine engine;

    // Make sure glue isn't stripped.
    app_dummy();

    memset(&engine, 0, sizeof(engine));
    state->userData = &engine;
    state->onAppCmd = engine_handle_cmd;
    state->onInputEvent = engine_handle_input;
    engine.app = state;

    // Prepare to monitor accelerometer
    engine.sensorManager = ASensorManager_getInstance();
    engine.accelerometerSensor = ASensorManager_getDefaultSensor(engine.sensorManager,
            ASENSOR_TYPE_ACCELEROMETER);

    if (state->savedState != NULL) {
        // We are starting with a previous saved state; restore from it.
        engine.state = *(struct saved_state*)state->savedState;
    }

    int ident, events;
    struct android_poll_source* source;

    while (true)
    {
        while ((ident = ALooper_pollAll(0, NULL, &events, (void**)&source)) >= 0)
        {
            if (source != NULL)
                source->process(state, source);

            if (state->destroyRequested != 0)
                return;
        }

        engine_draw_frame(&engine);
    }

}

效果如图所示。

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