初始化工作

//step1. 創(chuàng)建SurfaceComposerClient對象mSession
mSession = new SurfaceComposerClient();
//step2. 創(chuàng)建SurfaceControl對象
sp<SurfaceControl> control = mSession->createSurface(name);
//step3. 設(shè)置Layer層級
SurfaceComposerClient::openGlobalTransaction();
control->setLayer(0x40000000);
SurfaceComposerClient::closeGlobalTransaction();
//step4. 創(chuàng)建Surface對象
sp<Surface> s = control->getSurface();

// initialize opengl and egl
const EGLint attribs[] = {
    EGL_RED_SIZE,   8,
    EGL_GREEN_SIZE, 8,
    EGL_BLUE_SIZE,  8,
    EGL_DEPTH_SIZE, 0,
    EGL_NONE
};
EGLint w, h, dummy;
EGLint numConfigs;
EGLConfig config;
EGLSurface surface;
EGLContext context;

//顯示器
EGLDisplay display = eglGetDisplay(EGL_DEFAULT_DISPLAY);

eglInitialize(display, 0, 0);
eglChooseConfig(display, attribs, &config, 1, &numConfigs);
//通過Surface對象創(chuàng)建opengl層的WindowSurface
surface = eglCreateWindowSurface(display, config, s.get(), NULL);
context = eglCreateContext(display, config, NULL, NULL);
eglQuerySurface(display, surface, EGL_WIDTH, &w);
eglQuerySurface(display, surface, EGL_HEIGHT, &h);

if (eglMakeCurrent(display, surface, surface, context) == EGL_FALSE)
    return NO_INIT;

mDisplay = display;
mContext = context;
mSurface = surface;
mWidth = w;
mHeight = h;
mFlingerSurfaceControl = control;
mFlingerSurface = s;

使用opengl進行繪制工作

bool BootAnimation::android()
{
    initTexture(&mAndroid[0], mAssets, "images/android-logo-mask.png");
    initTexture(&mAndroid[1], mAssets, "images/android-logo-shine.png");

    // clear screen
    glShadeModel(GL_FLAT);
    glDisable(GL_DITHER);
    glDisable(GL_SCISSOR_TEST);
    glClearColor(0,0,0,1);
    glClear(GL_COLOR_BUFFER_BIT);
    eglSwapBuffers(mDisplay, mSurface);

    glEnable(GL_TEXTURE_2D);
    glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

    const GLint xc = (mWidth  - mAndroid[0].w) / 2;
    const GLint yc = (mHeight - mAndroid[0].h) / 2;
    const Rect updateRect(xc, yc, xc + mAndroid[0].w, yc + mAndroid[0].h);

    glScissor(updateRect.left, mHeight - updateRect.bottom, updateRect.width(),
            updateRect.height());

    // Blend state
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

    const nsecs_t startTime = systemTime();
    do {
        nsecs_t now = systemTime();
        double time = now - startTime;
        float t = 4.0f * float(time / us2ns(16667)) / mAndroid[1].w;
        GLint offset = (1 - (t - floorf(t))) * mAndroid[1].w;
        GLint x = xc - offset;

        glDisable(GL_SCISSOR_TEST);
        glClear(GL_COLOR_BUFFER_BIT);

        glEnable(GL_SCISSOR_TEST);
        glDisable(GL_BLEND);
        glBindTexture(GL_TEXTURE_2D, mAndroid[1].name);
        glDrawTexiOES(x,                 yc, 0, mAndroid[1].w, mAndroid[1].h);
        glDrawTexiOES(x + mAndroid[1].w, yc, 0, mAndroid[1].w, mAndroid[1].h);

        glEnable(GL_BLEND);
        glBindTexture(GL_TEXTURE_2D, mAndroid[0].name);
        glDrawTexiOES(xc, yc, 0, mAndroid[0].w, mAndroid[0].h);

        EGLBoolean res = eglSwapBuffers(mDisplay, mSurface);
        if (res == EGL_FALSE)
            break;

        // 12fps: don't animate too fast to preserve CPU
        const nsecs_t sleepTime = 83333 - ns2us(systemTime() - now);
        if (sleepTime > 0)
            usleep(sleepTime);

        checkExit();
    } while (!exitPending());

    glDeleteTextures(1, &mAndroid[0].name);
    glDeleteTextures(1, &mAndroid[1].name);
    //add to stop boot music 
    this->stopBootMusic();
    return false;
}