<Android Framework 之路>BootAnimation（2）

前言

上一篇主要讲解了BootAnimation是从何而来，如何启动，从开机，到SurfaceFlinger服务起来，然后到执行开机动画，如果要深入的看里面的代码，是需要花一定的时间的，我们旨在了解大致的流程，具体流程中的函数，变量意义，具体实现，读者请自研。
由来已知，执行待述~

###BootAnimation执行
1. 代码位置
frameworks/base/cmds/bootanimation
目录中包含如下文件

文件名	作用
Android.mk	mk文件，编译模块使用
AudioPlayer.cpp、AudioPlayer.h	音频播放
BootAnimation.cpp、BootAnimation.h	开机动画的源文件和头文件
bootanimation_main.cpp	开机动画的入口

2. 源码分析
bootanimation_main.cpp
文件中定义main函数，也就是C语言中的执行文件的入口函数

int main(int argc, char** argv)
{
//宏定义判断是否设置进程的优先级
#if defined(HAVE_PTHREADS)
    setpriority(PRIO_PROCESS, 0, ANDROID_PRIORITY_DISPLAY);
#endif

    char value[PROPERTY_VALUE_MAX];
    //这个配置项决定是否存在开机动画
    property_get("debug.sf.nobootanimation", value, "0");
    int noBootAnimation = atoi(value);
    ALOGI_IF(noBootAnimation,  "boot animation disabled");
    if (!noBootAnimation) {
        //创建ProcessSate对象
        // 这个过程会打开/dev/binder设备，形成和内核binder机制的交互的通道; 映射fd到内存
        sp<ProcessState> proc(ProcessState::self());
        //创建线程并加入到线程池
        ProcessState::self()->startThreadPool();

        // 创建开机动画对象
        sp<BootAnimation> boot = new BootAnimation();
        //把主线程加入到线程池
        IPCThreadState::self()->joinThreadPool();

    }
    return 0;
}

创建开机动画对象会执行到BootAnimation的构造方法，先看下BootAnimation的头文件
BootAnimation.h

......
namespace android {

class AudioPlayer;
class Surface;
class SurfaceComposerClient;
class SurfaceControl;

// ---------------------------------------------------------------------------

class BootAnimation : public Thread, public IBinder::DeathRecipient
{
public:
                BootAnimation();
    virtual     ~BootAnimation();

    sp<SurfaceComposerClient> session() const;

private:
   virtual bool        threadLoop();
   virtual status_t    readyToRun();
   virtual void        onFirstRef();
   virtual void        binderDied(const wp<IBinder>& who);

   //Texture类定义
   struct Texture {
       GLint   w; //宽度
       GLint   h; //高度
       GLuint  name; //名称
   };
   //动画内容结构体
   struct Animation {
       //动画帧
       struct Frame {
           String8 name;
           FileMap* map;
           mutable GLuint tid;
           bool operator < (const Frame& rhs) const {
               return name < rhs.name;
           }
       };
       //动画部分，因为动画可能是由几个部分组成
       struct Part {
           int count;
           int pause;
           String8 path;
           SortedVector<Frame> frames;
           bool playUntilComplete;
           float backgroundColor[3];
           FileMap* audioFile;
       };
       int fps;
       int width;
       int height;
       Vector<Part> parts;
   };

   status_t initTexture(Texture* texture, AssetManager& asset, const char* name);
   status_t initTexture(const Animation::Frame& frame);
   bool android();
   bool readFile(const char* name, String8& outString);
   bool movie();

   void checkExit();

   sp<SurfaceComposerClient>       mSession;
   sp<AudioPlayer>                 mAudioPlayer;
   AssetManager mAssets;
   Texture     mAndroid[2];
   int         mWidth;
   int         mHeight;
   EGLDisplay  mDisplay;
   EGLDisplay  mContext;
   EGLDisplay  mSurface;
   sp<SurfaceControl> mFlingerSurfaceControl;
   sp<Surface> mFlingerSurface;
   ZipFileRO   *mZip;
};

// ---------------------------------------------------------------------------

}; // namespace android

#endif // ANDROID_BOOTANIMATION_H

大致的定义和声明就是这么多，看下具体实现
BootAnimation.cpp
首先执行构造方法

BootAnimation::BootAnimation() : Thread(false), mZip(NULL)
{
    //用于界面显示的mSession，与SurfaceFlinger交互的客户端
    mSession = new SurfaceComposerClient();
}

然后执行

void BootAnimation::onFirstRef() {
    status_t err = mSession->linkToComposerDeath(this);
    ALOGE_IF(err, "linkToComposerDeath failed (%s) ", strerror(-err));
    if (err == NO_ERROR) {
        run("BootAnimation", PRIORITY_DISPLAY);
    }
}

由于BootAnimation继承Thread类，首先会调用readyToRun函数

status_t BootAnimation::readyToRun() {
    mAssets.addDefaultAssets();

    sp<IBinder> dtoken(SurfaceComposerClient::getBuiltInDisplay(
            ISurfaceComposer::eDisplayIdMain));
    DisplayInfo dinfo;
    status_t status = SurfaceComposerClient::getDisplayInfo(dtoken, &dinfo);
    if (status)
        return -1;

    // create the native surface
    sp<SurfaceControl> control = session()->createSurface(String8("BootAnimation"),
            dinfo.w, dinfo.h, PIXEL_FORMAT_RGB_565);

    SurfaceComposerClient::openGlobalTransaction();
    control->setLayer(0x40000000);
    SurfaceComposerClient::closeGlobalTransaction();

    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;

    EGLDisplay display = eglGetDisplay(EGL_DEFAULT_DISPLAY);

    eglInitialize(display, 0, 0);
    eglChooseConfig(display, attribs, &config, 1, &numConfigs);
    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;

    // If the device has encryption turned on or is in process
    // of being encrypted we show the encrypted boot animation.
    char decrypt[PROPERTY_VALUE_MAX];
    property_get("vold.decrypt", decrypt, "");

    bool encryptedAnimation = atoi(decrypt) != 0 || !strcmp("trigger_restart_min_framework", decrypt);

    ZipFileRO* zipFile = NULL;
    if ((encryptedAnimation &&
            (access(SYSTEM_ENCRYPTED_BOOTANIMATION_FILE, R_OK) == 0) &&
            ((zipFile = ZipFileRO::open(SYSTEM_ENCRYPTED_BOOTANIMATION_FILE)) != NULL)) ||

            ((access(OEM_BOOTANIMATION_FILE, R_OK) == 0) &&
            ((zipFile = ZipFileRO::open(OEM_BOOTANIMATION_FILE)) != NULL)) ||

            ((access(SYSTEM_BOOTANIMATION_FILE, R_OK) == 0) &&
            ((zipFile = ZipFileRO::open(SYSTEM_BOOTANIMATION_FILE)) != NULL))) {
        mZip = zipFile;
    }

    return NO_ERROR;
}

上面主要做两个操作：
1. 初始化显示界面用于播放开机动画，egl的一些内容；
2. 根据手机是否加密选择不同的开机动画文件，然后拿到入口zipFile
其中用到了一个文件路径在BootAnimation.cpp的开头有定义

#define OEM_BOOTANIMATION_FILE "/oem/media/bootanimation.zip"   //这个应该是OEM厂商自己定制

#define SYSTEM_BOOTANIMATION_FILE "/system/media/bootanimation.zip"   //正常情况下的Android原始开机动画

#define SYSTEM_ENCRYPTED_BOOTANIMATION_FILE "/system/media/bootanimation-encrypted.zip" //加密手机的开机动画

readyToRun方法执行完之后，接着看threaLoop函数

bool BootAnimation::threadLoop()
{
    bool r;
    // We have no bootanimation file, so we use the stock android logo
    // animation.
    if (mZip == NULL) {
        r = android(); //没有开机动画文件，执行android logo
    } else {
        r = movie(); //存在开机动画文件，则执行对应的开机动画文件解析出来的内容
    }

    eglMakeCurrent(mDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
    eglDestroyContext(mDisplay, mContext);
    eglDestroySurface(mDisplay, mSurface);
    mFlingerSurface.clear();
    mFlingerSurfaceControl.clear();
    eglTerminate(mDisplay);
    IPCThreadState::self()->stopProcess();
    return r;
}

——————————————>android()

bool BootAnimation::android()
{
    //初始化两个纹理用于显示logo
    initTexture(&mAndroid[0], mAssets, "images/android-logo-mask.png");
    initTexture(&mAndroid[1], mAssets, "images/android-logo-shine.png");

    // clear screen 清屏
    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();
    //不停的显示知道exitPending()返回true
    do {
        ......
        EGLBoolean res = eglSwapBuffers(mDisplay, mSurface);
        ......

        checkExit();
    } while (!exitPending());
    glDeleteTextures(1, &mAndroid[0].name);
    glDeleteTextures(1, &mAndroid[1].name);
    return false;
}

主要工作，初始化显示的logo纹理，不断刷新界面直到exitPending()返回true，exitPenging()是Thread类中定义的函数，在checkExit()函数中通过requestExit()来执行退出

void BootAnimation::checkExit() {
    // Allow surface flinger to gracefully request shutdown
    char value[PROPERTY_VALUE_MAX];
    //EXIT_PROP_NAME "service.bootanim.exit" 这个配置项在SurfaceFlinger的bootFinished函数中设置为1，然后这里才能退出开机动画，这个过程设计到开机启动到launcher的整个过程，这里不赘述
    property_get(EXIT_PROP_NAME, value, "0");
    int exitnow = atoi(value);
    if (exitnow) {
        requestExit();
        if (mAudioPlayer != NULL) {
            mAudioPlayer->requestExit();
        }
    }
}

——————————————>movie()
movie()这个函数有点长，我们截断一点一点的看
1. 读取bootanimation.zip中的配置文件

    if (!readFile("desc.txt", desString)) {
        return false;
    }
    char const* s = desString.string();
    //读取desc.txt文件
    // Create and initialize an AudioPlayer if we have an audio_conf.txt file
    String8 audioConf;
    //判断是否需要创建AudioPlayer,这部分我们暂时不关注
    if (readFile("audio_conf.txt", audioConf)) {
        mAudioPlayer = new AudioPlayer;
        if (!mAudioPlayer->init(audioConf.string())) {
            ALOGE("mAudioPlayer.init failed");
            mAudioPlayer = NULL;
        }
    }

1. 解析desc.txt文件，就是上面拿到的那个char const *s

for (;;) {
        //一行一行的截取
        const char* endl = strstr(s, "
");
        if (!endl) break;
        String8 line(s, endl - s);
        const char* l = line.string();
        //几个需要捕获的参数,帧率 宽高，次数
        int fps, width, height, count, pause;
        char path[ANIM_ENTRY_NAME_MAX];
        char color[7] = "000000"; // default to black if unspecified

        char pathType;
        //读取帧率和宽高
        if (sscanf(l, "%d %d %d", &width, &height, &fps) == 3) {
            // ALOGD("> w=%d, h=%d, fps=%d", width, height, fps);
            animation.width = width;
            animation.height = height;
            animation.fps = fps;
        }
        //或者读取part内容
        else if (sscanf(l, " %c %d %d %s #%6s", &pathType, &count, &pause, path, color) >= 4) {
            // ALOGD("> type=%c, count=%d, pause=%d, path=%s, color=%s", pathType, count, pause, path, color);
            Animation::Part part;
            part.playUntilComplete = pathType == 'c';
            part.count = count;
            part.pause = pause;
            part.path = path;
            part.audioFile = NULL;
            if (!parseColor(color, part.backgroundColor)) {
                ALOGE("> invalid color '#%s'", color);
                part.backgroundColor[0] = 0.0f;
                part.backgroundColor[1] = 0.0f;
                part.backgroundColor[2] = 0.0f;
            }
            animation.parts.add(part);
        }

        s = ++endl;
    }

1. 读取所有的数据

    // read all the data structures
    const size_t pcount = animation.parts.size();
    void *cookie = NULL;
    if (!mZip->startIteration(&cookie)) {
        return false;
    }

    ZipEntryRO entry;
    char name[ANIM_ENTRY_NAME_MAX];
    while ((entry = mZip->nextEntry(cookie)) != NULL) {
        const int foundEntryName = mZip->getEntryFileName(entry, name, ANIM_ENTRY_NAME_MAX);
        if (foundEntryName > ANIM_ENTRY_NAME_MAX || foundEntryName == -1) {
            ALOGE("Error fetching entry file name");
            continue;
        }

        const String8 entryName(name);
        const String8 path(entryName.getPathDir());
        const String8 leaf(entryName.getPathLeaf());
        if (leaf.size() > 0) {
            for (size_t j=0 ; j<pcount ; j++) {
                if (path == animation.parts[j].path) {
                    int method;
                    // supports only stored png files
                    if (mZip->getEntryInfo(entry, &method, NULL, NULL, NULL, NULL, NULL)) {
                        if (method == ZipFileRO::kCompressStored) {
                            FileMap* map = mZip->createEntryFileMap(entry);
                            if (map) {
                                Animation::Part& part(animation.parts.editItemAt(j));
                                if (leaf == "audio.wav") {
                                    // a part may have at most one audio file
                                    part.audioFile = map;
                                } else {
                                    Animation::Frame frame;
                                    frame.name = leaf;
                                    frame.map = map;
                                    part.frames.add(frame);
                                }
                            }
                        }
                    }
                }
            }
        }
    }

    mZip->endIteration(cookie);

1. 显示动画

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

    eglSwapBuffers(mDisplay, mSurface);

    glBindTexture(GL_TEXTURE_2D, 0);
    glEnable(GL_TEXTURE_2D);
    glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    const int xc = (mWidth - animation.width) / 2;
    const int yc = ((mHeight - animation.height) / 2);
    nsecs_t lastFrame = systemTime();
    nsecs_t frameDuration = s2ns(1) / animation.fps;

    Region clearReg(Rect(mWidth, mHeight));
    clearReg.subtractSelf(Rect(xc, yc, xc+animation.width, yc+animation.height));

    for (size_t i=0 ; i<pcount ; i++) {
        const Animation::Part& part(animation.parts[i]);
        const size_t fcount = part.frames.size();
        glBindTexture(GL_TEXTURE_2D, 0);

        for (int r=0 ; !part.count || r<part.count ; r++) {
            // Exit any non playuntil complete parts immediately
            if(exitPending() && !part.playUntilComplete)
                break;

            // only play audio file the first time we animate the part
            if (r == 0 && mAudioPlayer != NULL && part.audioFile) {
                mAudioPlayer->playFile(part.audioFile);
            }

            glClearColor(
                    part.backgroundColor[0],
                    part.backgroundColor[1],
                    part.backgroundColor[2],
                    1.0f);

            for (size_t j=0 ; j<fcount && (!exitPending() || part.playUntilComplete) ; j++) {
                const Animation::Frame& frame(part.frames[j]);
                nsecs_t lastFrame = systemTime();

                if (r > 0) {
                    glBindTexture(GL_TEXTURE_2D, frame.tid);
                } else {
                    if (part.count != 1) {
                        glGenTextures(1, &frame.tid);
                        glBindTexture(GL_TEXTURE_2D, frame.tid);
                        glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                        glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
                    }
                    initTexture(frame);
                }

                if (!clearReg.isEmpty()) {
                    Region::const_iterator head(clearReg.begin());
                    Region::const_iterator tail(clearReg.end());
                    glEnable(GL_SCISSOR_TEST);
                    while (head != tail) {
                        const Rect& r(*head++);
                        glScissor(r.left, mHeight - r.bottom,
                                r.width(), r.height());
                        glClear(GL_COLOR_BUFFER_BIT);
                    }
                    glDisable(GL_SCISSOR_TEST);
                }
                glDrawTexiOES(xc, yc, 0, animation.width, animation.height);
                eglSwapBuffers(mDisplay, mSurface);

                nsecs_t now = systemTime();
                nsecs_t delay = frameDuration - (now - lastFrame);
                //ALOGD("%lld, %lld", ns2ms(now - lastFrame), ns2ms(delay));
                lastFrame = now;

                if (delay > 0) {
                    struct timespec spec;
                    spec.tv_sec  = (now + delay) / 1000000000;
                    spec.tv_nsec = (now + delay) % 1000000000;
                    int err;
                    do {
                        err = clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &spec, NULL);
                    } while (err<0 && errno == EINTR);
                }

                checkExit();
            }

            usleep(part.pause * ns2us(frameDuration));

            // For infinite parts, we've now played them at least once, so perhaps exit
            if(exitPending() && !part.count)
                break;
        }

        // free the textures for this part
        if (part.count != 1) {
            for (size_t j=0 ; j<fcount ; j++) {
                const Animation::Frame& frame(part.frames[j]);
                glDeleteTextures(1, &frame.tid);
            }
        }
    }

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备注

主要工作，贴代码，加自己的理解，有问题留言。