XDrawLine(display_, x_window_, x_gc_, 0, 0, 50, 50);

typedef struct {
  //启动、销毁、初始化
  FlutterEngineRunFnPtr Run;
  FlutterEngineShutdownFnPtr Shutdown;
  FlutterEngineInitializeFnPtr Initialize;
  //平台发送event事件给flutter
  FlutterEngineSendPointerEventFnPtr SendPointerEvent;
  FlutterEngineSendKeyEventFnPtr SendKeyEvent;
  //PlatformMessage
  FlutterEngineSendPlatformMessageFnPtr SendPlatformMessage;
  FlutterEnginePlatformMessageCreateResponseHandleFnPtr
  //外接纹理
  FlutterEngineRegisterExternalTextureFnPtr RegisterExternalTexture;
  //task
  FlutterEnginePostRenderThreadTaskFnPtr PostRenderThreadTask;
  //...
} FlutterEngineProcTable;

FlutterELinuxEngine::RunWithEntrypoint(...){
    embedder_api_.Run(&renderer_config, ...);
}

bool FlutterELinuxEngine::Stop() {
     embedder_api_.Shutdown(engine_);
}

void FlutterELinuxEngine::SendPointerEvent(...) {
   embedder_api_.SendPointerEvent(engine_, &event, 1);
}

bool FlutterELinuxEngine::SendPlatformMessage(){
    embedder_api_.PlatformMessageCreateResponseHandle(...);
}

bool FlutterELinuxEngine::RegisterExternalTexture(int64_t texture_id) {
  embedder_api_.RegisterExternalTexture(engine_, texture_id);
}

FlutterELinuxEngine::RunWithEntrypoint(...){
    auto renderer_config = GetRendererConfig();
    embedder_api_.Run(&renderer_config, ...);
}

/skia申请bacbuffer
sk_sp<SkSurface> EmbedderSurfaceSoftware::AcquireBackingStore(){
  SkImageInfo info =SkImageInfo::Make(...);
  sk_surface_ = SkSurface::MakeRaster(info, nullptr);
}

bool EmbedderSurfaceSoftware::PresentBackingStore(){
    //消费buffer 纹理数据
    backing_store->peekPixels(&pixmap)
    //通过embderapi透传出去
    software_dispatch_table_.software_present_backing_store(
      pixmap.addr(),      //
      pixmap.rowBytes(),  //
      pixmap.height()     //
  );
}

//软件解码,传过来skia解码后的bitmap
FlutterRendererConfig GetSoftwareRendererConfig(){
  FlutterRendererConfig config = {};
  config.type = kSoftware;
  config.software.surface_present_callback = [](...) {
    host->view()->PresentSoftwareBitmap(allocation,row_bytes,height);
  };
  return config;
}

//通过xlib上屏纹理数据 (wayland类似)
bool ELinuxWindowX11::OnBitmapSurfaceUpdated(...){
  //...
  auto img = XCreateImage(display_,x_visual_,deps,ZPixmap,0,data,width,height,32,0);
  XPutImage(display_,x_window_,x_gc_,img,0,0,0,0,width,height);
}



//硬件解码,走opengl
FlutterRendererConfig GetRendererConfig() {
    FlutterRendererConfig config = {};
    config.type = kOpenGL;
    config.open_gl.make_current =  [](...) -> bool {
        return host->view()->MakeCurrent();
    }
}

typedef struct {
  size_t struct_size;
  BoolCallback make_current;
  BoolCallback clear_current;
  BoolCallback present;
  UIntCallback fbo_callback;
  BoolCallback make_resource_current;
  bool fbo_reset_after_present;
  TransformationCallback surface_transformation;
  ProcResolver gl_proc_resolver;
  TextureFrameCallback gl_external_texture_frame_callback;
  UIntFrameInfoCallback fbo_with_frame_info_callback;
} FlutterOpenGLRendererConfig;

 std::unique_ptr<flutter::WindowBindingHandler> window_wrapper =

#if defined(DISPLAY_BACKEND_TYPE_DRM_GBM)
      std::make_unique<flutter::ELinuxWindowDrm<flutter::NativeWindowDrmGbm>>(
          view_properties);
          
#elif defined(DISPLAY_BACKEND_TYPE_DRM_EGLSTREAM)
      std::make_unique<
          flutter::ELinuxWindowDrm<flutter::NativeWindowDrmEglstream>>(
          view_properties);
          
#elif defined(DISPLAY_BACKEND_TYPE_X11)
      std::make_unique<flutter::ELinuxWindowX11>(view_properties);
      
#elif defined(DISPLAY_BACKEND_TYPE_WAYLAND)
      std::make_unique<flutter::ELinuxWindowWayland>(view_properties);
      
#elif defined(DISPLAY_BACKEND_TYPE_FRAME_BUFFER)
      std::make_unique<flutter::ELinuxWindowFrameBuffer>(view_properties);
#endif

NativeWindowFrameBuffer::NativeWindowFrameBuffer(...) {
    //打开fb设备文件
    m_fbfd_ = open("/dev/fb0", O_RDWR);
    //获取fb屏幕信息
    ioctl(m_fbfd_, FBIOGET_VSCREENINFO, &m_vinfo_);
    //映射内存
    fb_base = (unsigned char*)mmap(0, screen_size * 2, PROT_READ | PROT_WRITE,
                                   MAP_SHARED, m_fbfd_, 0); 
    //获取支持的lcd格式: rgba8888...                               
     rgb = findFormat();
    //设置tty为KD_GRAPHICS模式,防止终端刷新,导致画面闪烁
    openDev()                                                                                         
}

//软解纹理数据更新
bool NativeWindowFrameBuffer::OnBitmapSurfaceUpdated(...){
    //...
    lcd_draw(fb_base,data);
}

//事件处理 监听linux的libinput库
int ELinuxWindowFrameBuffer::OninputEvent(...) {
  switch (event_type) {
      case LIBINPUT_EVENT_KEYBOARD_KEY:
       //转换event后,通过embederapi发给flutter
        OnKeyEvent(event);
        break;
      case LIBINPUT_EVENT_TOUCH_DOWN:
        OnTouchDown(event); 
        break;
      default:
        break;
  }

bool NativeWindowFrameBuffer::OnBitmapSurfaceUpdated(...){
    //START
    for (x = 0; x < m_vinfo_.xres; x++){
        for (y = 0; y < m_vinfo_.yres; y++){
          //rgba8888->rgb565
          lcd_put_pixel(fb_base, x, y, allocation);
        }
    }
    //END
}

 bool NativeWindowFrameBuffer::OnBitmapSurfaceUpdated(..data){
   //... check
   memcpy(fb_base_void, data, sizeof(char) * m_vinfo_.xres * m_vinfo_.yres * 2);
 }

void NativeWindowFrameBuffer::SwapBuffers() {
   //切换buffer
   m_vinfo_.yoffset = m_buffer_index_ * m_vinfo_.yres;
   //显示buffer内容
   ioctl(m_fbfd_, FBIOPAN_DISPLAY, &m_vinfo_);
   m_buffer_index_ = (m_buffer_index_ + 1) % 2;
   m_backbuffer = m_framebuffer + m_buffer_index_ * m_page_size_;
   //vsync
   ioctl(m_fbfd_, FBIO_WAITFORVSYNC, &dummy);
}