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yuv420native_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 <cutils/memory.h>#include <unistd.h>#include <utils/Log.h>#include <binder/IPCThreadState.h>#include <binder/ProcessState.h>#include <binder/IServiceManager.h>#include <media/stagefright/foundation/ADebug.h>#include <gui/Surface.h>#include <gui/SurfaceComposerClient.h>#include <gui/ISurfaceComposer.h>#include <ui/DisplayInfo.h>#include <android/native_window.h>#include <system/window.h>#include <ui/GraphicBufferMapper.h>//ANativeWindow 就是surface，对应surface.cpp里的codeusing 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<ANativeWindow> &nativeWindow,int width,int height) { sp<ANativeWindow> 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<ProcessState> proc(ProcessState::self()); ProcessState::self()->startThreadPool(); // create a client to surfaceflinger sp<SurfaceComposerClient> client = new SurfaceComposerClient(); sp<IBinder> 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> 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> 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:= MyShowYUVLOCAL_MODULE_TAGS := testsinclude $(BUILD_EXECUTABLE)转载请注明出处http://blog.csdn.net/tung214/article/details/37651825