# NativeImage开发指导 ## 场景介绍 NativeImage是`OpenHarmony`提供**Surface关联OpenGL外部纹理**的模块，表示图形队列的消费者端。开发者可以通过`NativeImage`接口接收和使用`Buffer`，并将`Buffer`关联输出到OpenGL外部纹理。 针对NativeImage，常见的开发场景如下： * 通过`NativeImage`提供的Native API接口创建`NativeImage`实例作为消费者端，获取与该实例对应的`NativeWindow`作为生产者端。`NativeWindow`相关接口可用于填充`Buffer`内容并提交，`NativeImage`将`Buffer`内容更新到OpenGL外部纹理上。本模块需要配合NativeWindow、NativeBuffer、EGL、GLES3模块一起使用。 ## 接口说明 | 接口名 | 描述 | | -------- | -------- | | OH_NativeImage_Create (uint32_t textureId, uint32_t textureTarget) | 创建一个OH_NativeImage实例，该实例与OpenGL ES的纹理ID和纹理目标相关联。 | | OH_NativeImage_AcquireNativeWindow (OH_NativeImage \*image) | 获取与OH_NativeImage相关联的OHNativeWindow指针，该OHNativeWindow后续不再需要时需要调用 OH_NativeWindow_DestroyNativeWindow释放。 | | OH_NativeImage_AttachContext (OH_NativeImage \*image, uint32_t textureId) | 将OH_NativeImage实例附加到当前OpenGL ES上下文，且该OpenGL ES纹理会绑定到 GL_TEXTURE_EXTERNAL_OES，并通过OH_NativeImage进行更新。 | | OH_NativeImage_DetachContext (OH_NativeImage \*image) | 将OH_NativeImage实例从当前OpenGL ES上下文分离。 | | OH_NativeImage_UpdateSurfaceImage (OH_NativeImage \*image) | 通过OH_NativeImage获取最新帧更新相关联的OpenGL ES纹理。 | | OH_NativeImage_GetTimestamp (OH_NativeImage \*image) | 获取最近调用OH_NativeImage_UpdateSurfaceImage的纹理图像的相关时间戳。 | | OH_NativeImage_GetTransformMatrix (OH_NativeImage \*image, float matrix[16]) | 获取最近调用OH_NativeImage_UpdateSurfaceImage的纹理图像的变化矩阵。 | | OH_NativeImage_Destroy (OH_NativeImage \*\*image) | 销毁通过OH_NativeImage_Create创建的OH_NativeImage实例，销毁后该OH_NativeImage指针会被赋值为空。 | 详细的接口说明请参考[native_image](../reference/native-apis/_o_h___native_image.md)。 ## 开发步骤 以下步骤描述了在**OpenHarmony**中如何使用`NativeImage`提供的Native API接口，创建`OH_NativeImage`实例作为消费者端，将数据内容更新到OpenGL外部纹理上。 **头文件** ```c++ #include #include #include #include #include #include ``` 1. **初始化EGL环境**。 这里提供一份初始化EGL环境的代码示例 ```c++ #include #include using GetPlatformDisplayExt = PFNEGLGETPLATFORMDISPLAYEXTPROC; constexpr const char* EGL_EXT_PLATFORM_WAYLAND = "EGL_EXT_platform_wayland"; constexpr const char* EGL_KHR_PLATFORM_WAYLAND = "EGL_KHR_platform_wayland"; constexpr int32_t EGL_CONTEXT_CLIENT_VERSION_NUM = 2; constexpr char CHARACTER_WHITESPACE = ' '; constexpr const char* CHARACTER_STRING_WHITESPACE = " "; constexpr const char* EGL_GET_PLATFORM_DISPLAY_EXT = "eglGetPlatformDisplayEXT"; EGLContext eglContext_ = EGL_NO_CONTEXT; EGLDisplay eglDisplay_ = EGL_NO_DISPLAY; static inline EGLConfig config_; // 检查egl扩展 static bool CheckEglExtension(const char* extensions, const char* extension) { size_t extlen = strlen(extension); const char* end = extensions + strlen(extensions); while (extensions < end) { size_t n = 0; if (*extensions == CHARACTER_WHITESPACE) { extensions++; continue; } n = strcspn(extensions, CHARACTER_STRING_WHITESPACE); if (n == extlen && strncmp(extension, extensions, n) == 0) { return true; } extensions += n; } return false; } // 获取当前的显示设备 static EGLDisplay GetPlatformEglDisplay(EGLenum platform, void* native_display, const EGLint* attrib_list) { static GetPlatformDisplayExt eglGetPlatformDisplayExt = NULL; if (!eglGetPlatformDisplayExt) { const char* extensions = eglQueryString(EGL_NO_DISPLAY, EGL_EXTENSIONS); if (extensions && (CheckEglExtension(extensions, EGL_EXT_PLATFORM_WAYLAND) || CheckEglExtension(extensions, EGL_KHR_PLATFORM_WAYLAND))) { eglGetPlatformDisplayExt = (GetPlatformDisplayExt)eglGetProcAddress(EGL_GET_PLATFORM_DISPLAY_EXT); } } if (eglGetPlatformDisplayExt) { return eglGetPlatformDisplayExt(platform, native_display, attrib_list); } return eglGetDisplay((EGLNativeDisplayType)native_display); } static void InitEGLEnv() { // 获取当前的显示设备 eglDisplay_ = GetPlatformEglDisplay(EGL_PLATFORM_OHOS_KHR, EGL_DEFAULT_DISPLAY, NULL); if (eglDisplay_ == EGL_NO_DISPLAY) { std::cout << "Failed to create EGLDisplay gl errno : " << eglGetError() << std::endl; } EGLint major, minor; // 初始化EGLDisplay if (eglInitialize(eglDisplay_, &major, &minor) == EGL_FALSE) { std::cout << "Failed to initialize EGLDisplay" << std::endl; } // 绑定图形绘制的API为OpenGLES if (eglBindAPI(EGL_OPENGL_ES_API) == EGL_FALSE) { std::cout << "Failed to bind OpenGL ES API" << std::endl; } unsigned int ret; EGLint count; EGLint config_attribs[] = { EGL_SURFACE_TYPE, EGL_WINDOW_BIT, EGL_RED_SIZE, 8, EGL_GREEN_SIZE, 8, EGL_BLUE_SIZE, 8, EGL_ALPHA_SIZE, 8, EGL_RENDERABLE_TYPE, EGL_OPENGL_ES3_BIT, EGL_NONE }; // 获取一个有效的系统配置信息 ret = eglChooseConfig(eglDisplay_, config_attribs, &config_, 1, &count); if (!(ret && static_cast(count) >= 1)) { std::cout << "Failed to eglChooseConfig" << std::endl; } static const EGLint context_attribs[] = { EGL_CONTEXT_CLIENT_VERSION, EGL_CONTEXT_CLIENT_VERSION_NUM, EGL_NONE }; // 创建上下文 eglContext_ = eglCreateContext(eglDisplay_, config_, EGL_NO_CONTEXT, context_attribs); if (eglContext_ == EGL_NO_CONTEXT) { std::cout << "Failed to create egl context %{public}x, error:" << eglGetError() << std::endl; } // 关联上下文 eglMakeCurrent(eglDisplay_, EGL_NO_SURFACE, EGL_NO_SURFACE, eglContext_); // EGL环境初始化完成 std::cout << "Create EGL context successfully, version" << major << "." << minor << std::endl; } ``` 2. **创建OH_NativeImage实例**。 ```c++ // 创建 OpenGL 纹理 GLuint textureId; glGenTextures(1, &textureId); // 创建 NativeImage 实例，关联 OpenGL 纹理 OH_NativeImage* image = OH_NativeImage_Create(textureId, GL_TEXTURE_2D); ``` 3. **获取对应的数据生产者端NativeWindow**。 ```c++ // 获取生产者NativeWindow OHNativeWindow* nativeWindow = OH_NativeImage_AcquireNativeWindow(image); ``` 4. **将生产的内容写入NativeWindowBuffer**。 1. 从NativeWindow中获取NativeWindowBuffer ```c++ OHNativeWindowBuffer* buffer = nullptr; int fenceFd; // 通过 OH_NativeWindow_NativeWindowRequestBuffer 获取 OHNativeWindowBuffer 实例 OH_NativeWindow_NativeWindowRequestBuffer(nativeWindow, &buffer, &fenceFd); BufferHandle *handle = OH_NativeWindow_GetBufferHandleFromNative(buffer); int code = SET_BUFFER_GEOMETRY; int32_t width = 0x100; int32_t height = 0x100; ret = OH_NativeWindow_NativeWindowHandleOpt(nativeWindow, code, width, height); ``` 3. 将生产的内容写入NativeWindowBuffer ```c++ static uint32_t value = 0x00; value++; uint32_t *pixel = static_cast(handle->virAddr); for (uint32_t x = 0; x < width; x++) { for (uint32_t y = 0; y < height; y++) { *pixel++ = value; } } ``` 4. 将NativeWindowBuffer提交到NativeWindow ```c++ // 设置刷新区域，如果Region中的Rect为nullptr,或者rectNumber为0，则认为NativeWindowBuffer全部有内容更改。 Region region{nullptr, 0}; // 通过OH_NativeWindow_NativeWindowFlushBuffer 提交给消费者使用，例如：显示在屏幕上。 OH_NativeWindow_NativeWindowFlushBuffer(nativeWindow, buffer, fenceFd, region); ``` 5. 用完需要销毁NativeWindow ```c++ OH_NativeWindow_DestroyNativeWindow(nativeWindow); ``` 5. **更新内容到OpenGL纹理**。 ```c++ // 更新内容到OpenGL纹理。 int32_t ret = OH_NativeImage_UpdateSurfaceImage(image); if (ret != 0) { std::cout << "OH_NativeImage_UpdateSurfaceImage failed" << std::endl; } // 获取最近调用OH_NativeImage_UpdateSurfaceImage的纹理图像的时间戳和变化矩阵。 int64_t timeStamp = OH_NativeImage_GetTimestamp(image); float matrix[16]; ret = OH_NativeImage_GetTransformMatrix(image, matrix); if (ret != 0) { std::cout << "OH_NativeImage_GetTransformMatrix failed" << std::endl; } ``` 6. **解绑OpenGL纹理，绑定到新的外部纹理上**。 ```c++ // 将OH_NativeImage实例从当前OpenGL ES上下文分离 ret = OH_NativeImage_DetachContext(image); if (ret != 0) { std::cout << "OH_NativeImage_DetachContext failed" << std::endl; } // 将OH_NativeImage实例附加到当前OpenGL ES上下文, 且该OpenGL ES纹理会绑定到 GL_TEXTURE_EXTERNAL_OES, 并通过OH_NativeImage进行更新 GLuint textureId2; glGenTextures(1, &textureId2); ret = OH_NativeImage_AttachContext(image, textureId2); ``` 7. **OH_NativeImage实例使用完需要销毁掉**。 ```c++ // 销毁OH_NativeImage实例 OH_NativeImage_Destroy(&image); ```