<Android Framework 之路>BootAnimation（2）

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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;

        }

    }

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, "\n");

        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;

    }

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);

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);

            }

        }

    }