Android用surface直接显示yuv数据（二）

上一篇文章主要是参照AwesomePlayer直接用SoftwareRenderer类来显示yuv，为了能用到这个类，不惜依赖了libstagefright、libstagefright_color_conversion等动态静态库，从而造成程序具有很高的耦合度，也不便于我们理解yuv数据直接显示的深层次原因。

    于是我开始研究SoftwareRenderer的具体实现，我们来提取SoftwareRenderer的核心代码，自己来实现yuv的显示。

    SoftwareRenderer就只有三个方法，一个构造函数，一个析构函数，还有一个负责显示的render方法。构造方法里有个很重要的地方native_window_set_buffers_geometry这里是配置即将申请的图形缓冲区的宽高和颜色空间，忽略了这个地方，画面将用默认的值显示，将造成显示不正确。render函数里最重要的三个地方，一个的dequeBuffer，一个是mapper，一个是queue_buffer。

 native_window_set_buffers_geometry;//设置宽高以及颜色空间yuv420
 native_window_dequeue_buffer_and_wait;//根据以上配置申请图形缓冲区
 mapper.lock(buf->handle, GRALLOC_USAGE_SW_WRITE_OFTEN, bounds, &dst));//将申请到的图形缓冲区跨进程映射到用户空间
 memcpy(dst, data, dst_y_size + dst_c_size*2);//填充yuv数据到图形缓冲区
 mNativeWindow->queueBuffer;//显示

以上五步是surface显示图形必不可少的五步。

有了以上分析，我们直接上代码：(yuv数据下载地址点击打开链接，放到sdcard)

main.cpp

 #include

 #include
 #include

 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 //ANativeWindow 就是surface，对应surface.cpp里的code
 using namespace android;

 //将x规整为y的倍数,也就是将x按y对齐
 static int ALIGN(int x, int y) {
     // y must be a power of 2.
     return (x + y - 1) & ~(y - 1);
 }

 void render(
         const void *data, size_t size, const sp &nativeWindow,int width,int height) {
     sp mNativeWindow = nativeWindow;
     int err;
     int mCropWidth = width;
     int mCropHeight = height;

     int halFormat = HAL_PIXEL_FORMAT_YV12;//颜色空间
     int bufWidth = (mCropWidth + 1) & ~1;//按2对齐
     int bufHeight = (mCropHeight + 1) & ~1;

     CHECK_EQ(0,
             native_window_set_usage(
             mNativeWindow.get(),
             GRALLOC_USAGE_SW_READ_NEVER | GRALLOC_USAGE_SW_WRITE_OFTEN
             | GRALLOC_USAGE_HW_TEXTURE | GRALLOC_USAGE_EXTERNAL_DISP));

     CHECK_EQ(0,
             native_window_set_scaling_mode(
             mNativeWindow.get(),
             NATIVE_WINDOW_SCALING_MODE_SCALE_TO_WINDOW));

     // Width must be multiple of 32???
     //很重要,配置宽高和和指定颜色空间yuv420
     //如果这里不配置好，下面deque_buffer只能去申请一个默认宽高的图形缓冲区
     CHECK_EQ(0, native_window_set_buffers_geometry(
                 mNativeWindow.get(),
                 bufWidth,
                 bufHeight,
                 halFormat));


     ANativeWindowBuffer *buf;//描述buffer
     //申请一块空闲的图形缓冲区
     if ((err = native_window_dequeue_buffer_and_wait(mNativeWindow.get(),
             &buf)) != 0) {
         ALOGW("Surface::dequeueBuffer returned error %d", err);
         return;
     }

     GraphicBufferMapper &mapper = GraphicBufferMapper::get();

     Rect bounds(mCropWidth, mCropHeight);

     void *dst;
     CHECK_EQ(0, mapper.lock(//用来锁定一个图形缓冲区并将缓冲区映射到用户进程
                 buf->handle, GRALLOC_USAGE_SW_WRITE_OFTEN, bounds, &dst));//dst就指向图形缓冲区首地址

     if (true){
         size_t dst_y_size = buf->stride * buf->height;
         size_t dst_c_stride = ALIGN(buf->stride / 2, 16);//1行v/u的大小
         size_t dst_c_size = dst_c_stride * buf->height / 2;//u/v的大小

         memcpy(dst, data, dst_y_size + dst_c_size*2);//将yuv数据copy到图形缓冲区
     }

     CHECK_EQ(0, mapper.unlock(buf->handle));

     if ((err = mNativeWindow->queueBuffer(mNativeWindow.get(), buf,
             -1)) != 0) {
         ALOGW("Surface::queueBuffer returned error %d", err);
     }
     buf = NULL;
 }

 bool getYV12Data(const char *path,unsigned char * pYUVData,int size){
     FILE *fp = fopen(path,"rb");
     if(fp == NULL){
         printf("read %s fail !!!!!!!!!!!!!!!!!!!\n",path);
         return false;
     }
     fread(pYUVData,size,1,fp);
     fclose(fp);
     return true;
 }

 int main(void){
     // set up the thread-pool
     sp proc(ProcessState::self());
     ProcessState::self()->startThreadPool();

     // create a client to surfaceflinger
     sp client = new SurfaceComposerClient();
     sp dtoken(SurfaceComposerClient::getBuiltInDisplay(
             ISurfaceComposer::eDisplayIdMain));
     DisplayInfo dinfo;
     //获取屏幕的宽高等信息
     status_t status = SurfaceComposerClient::getDisplayInfo(dtoken, &dinfo);
     printf("w=%d,h=%d,xdpi=%f,ydpi=%f,fps=%f,ds=%f\n",
         dinfo.w, dinfo.h, dinfo.xdpi, dinfo.ydpi, dinfo.fps, dinfo.density);
     if (status)
         return -1;
     //创建surface
     sp surfaceControl = client->createSurface(String8("testsurface"),
             dinfo.w, dinfo.h, PIXEL_FORMAT_RGBA_8888, 0);

 /*************************get yuv data from file;****************************************/
     printf("[%s][%d]\n",__FILE__,__LINE__);
     int width,height;
     width = 320;
     height = 240;
     int size = width * height * 3/2;
     unsigned char *data = new unsigned char[size];
     const char *path = "/mnt/sdcard/yuv_320_240.yuv";
     getYV12Data(path,data,size);//get yuv data from file;

 /*********************配置surface*******************************************************************/
     SurfaceComposerClient::openGlobalTransaction();
     surfaceControl->setLayer(100000);//设定Z坐标
     surfaceControl->setPosition(100, 100);//以左上角为(0,0)设定显示位置
     surfaceControl->setSize(width, height);//设定视频显示大小
     SurfaceComposerClient::closeGlobalTransaction();
     sp surface = surfaceControl->getSurface();
     printf("[%s][%d]\n",__FILE__,__LINE__);

 /**********************显示yuv数据******************************************************************/
     render(data,size,surface,width,height);
     printf("[%s][%d]\n",__FILE__,__LINE__);

     IPCThreadState::self()->joinThreadPool();//可以保证画面一直显示，否则瞬间消失
     IPCThreadState::self()->stopProcess();
     return 0;
 }

Android.mk (这次依赖的库少了很多)

 LOCAL_PATH:= $(call my-dir)
 include $(CLEAR_VARS)

 LOCAL_SRC_FILES:= \
     main.cpp

 LOCAL_SHARED_LIBRARIES := \
     libcutils \
     libutils \
     libbinder \
     libui \
     libgui \
     libstagefright_foundation

 LOCAL_MODULE:= MyShowYUV

 LOCAL_MODULE_TAGS := tests

 include $(BUILD_EXECUTABLE)

转载请注明出处 http://blog.csdn.net/tung214/article/details/37651825