harmony 鸿蒙NativeWindow开发指导

  • 2022-08-09
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NativeWindow开发指导

场景介绍

NativeWindow是本地平台化窗口,表示图形队列的生产者端。开发者可以通过NativeWindow接口进行申请和提交Buffer,配置Buffer属性信息。 针对NativeWindow,常见的开发场景如下:

  • 通过NativeWindow提供的Native API接口申请图形Buffer,并将生产图形内容写入图形Buffer,最终提交Buffer到图形队列
  • 在适配EGL层的eglswapbuffer接口时,进行申请和提交Buffer

接口说明

接口名 描述
OH_NativeWindow_NativeWindowRequestBuffer (OHNativeWindow *window, OHNativeWindowBuffer **buffer, int *fenceFd) 通过OHNativeWindow对象申请一块OHNativeWindowBuffer,用以内容生产。
OH_NativeWindow_NativeWindowFlushBuffer (OHNativeWindow *window, OHNativeWindowBuffer *buffer, int fenceFd, Region region) 通过OHNativeWindow将生产好内容的OHNativeWindowBuffer放回到Buffer队列中,用以内容消费。
OH_NativeWindow_NativeWindowHandleOpt (OHNativeWindow *window, int code,…) 设置/获取OHNativeWindow的属性,包括设置/获取宽高、内容格式等。

详细的接口说明请参考native_window

开发步骤

以下步骤描述了如何使用NativeWindow提供的Native API接口,申请图形Buffer,并将生产图形内容写入图形Buffer后,最终提交Buffer到图形队列。

添加动态链接库

CMakeLists.txt中添加以下lib。

libace_ndk.z.so
libnative_window.so

头文件

#include <ace/xcomponent/native_interface_xcomponent.h>
#include <native_window/external_window.h>
  1. 获取OHNativeWindow实例

    可在OH_NativeXComponent_Callback提供的接口中获取OHNativeWindow,下面提供一份代码示例。XComponent模块的具体使用方法请参考XComponent开发指导

    1. 在xxx.ets中添加一个XComponent组件。 ts XComponent({ id: 'xcomponentId', type: 'surface', libraryname: 'entry'}) .width(360) .height(360)
    2. 在 native c++ 层获取 NativeXComponent。 c++ napi_value exportInstance = nullptr; // 用来解析出被wrap了NativeXComponent指针的属性 napi_get_named_property(env, exports, OH_NATIVE_XCOMPONENT_OBJ, &exportInstance); OH_NativeXComponent *nativeXComponent = nullptr; // 通过napi_unwrap接口,解析出NativeXComponent的实例指针 napi_unwrap(env, exportInstance, reinterpret_cast<void**>(&nativeXComponent)); // 获取XComponentId char idStr[OH_XCOMPONENT_ID_LEN_MAX + 1] = {}; uint64_t idSize = OH_XCOMPONENT_ID_LEN_MAX + 1; OH_NativeXComponent_GetXComponentId(nativeXComponent, idStr, &idSize);
    3. 定义 OH_NativeXComponent_Callback。 c++ // 定义回调函数 void OnSurfaceCreatedCB(OH_NativeXComponent* component, void* window) { // 可获取 OHNativeWindow 实例 OHNativeWindow* nativeWindow = static_cast<OHNativeWindow*>(window); // ... } void OnSurfaceChangedCB(OH_NativeXComponent* component, void* window) { // 可获取 OHNativeWindow 实例 OHNativeWindow* nativeWindow = static_cast<OHNativeWindow*>(window); // ... } void OnSurfaceDestroyedCB(OH_NativeXComponent* component, void* window) { // 可获取 OHNativeWindow 实例 OHNativeWindow* nativeWindow = static_cast<OHNativeWindow*>(window); // ... } void DispatchTouchEventCB(OH_NativeXComponent* component, void* window) { // 可获取 OHNativeWindow 实例 OHNativeWindow* nativeWindow = static_cast<OHNativeWindow*>(window); // ... } c++ // 初始化 OH_NativeXComponent_Callback OH_NativeXComponent_Callback callback; callback.OnSurfaceCreated = OnSurfaceCreatedCB; callback.OnSurfaceChanged = OnSurfaceChangedCB; callback.OnSurfaceDestroyed = OnSurfaceDestroyedCB; callback.DispatchTouchEvent = DispatchTouchEventCB;
    4. 将 OH_NativeXComponent_Callback 注册给 NativeXComponent。 c++ // 注册回调函数 OH_NativeXComponent_RegisterCallback(nativeXComponent, &callback);
  2. 设置OHNativeWindowBuffer的属性。使用OH_NativeWindow_NativeWindowHandleOpt设置OHNativeWindowBuffer的属性。

    // 设置 OHNativeWindowBuffer 的宽高
    int32_t code = SET_BUFFER_GEOMETRY;
    int32_t width = 0x100;
    int32_t height = 0x100;
    // 这里的nativeWindow是从上一步骤中的回调函数中获得的
    int32_t ret = OH_NativeWindow_NativeWindowHandleOpt(nativeWindow, code, width, height);
    
  3. 从图形队列申请OHNativeWindowBuffer

    OHNativeWindowBuffer* buffer = nullptr;
    int fenceFd;
    // 通过 OH_NativeWindow_NativeWindowRequestBuffer 获取 OHNativeWindowBuffer 实例
    OH_NativeWindow_NativeWindowRequestBuffer(nativeWindow, &buffer, &fenceFd);
    // 通过 OH_NativeWindow_GetBufferHandleFromNative 获取 buffer 的 handle
    BufferHandle* bufferHandle = OH_NativeWindow_GetBufferHandleFromNative(buffer);
    
  4. 内存映射mmap

    #include <sys/mman.h>
    
    
    // 使用系统mmap接口拿到bufferHandle的内存虚拟地址
    void* mappedAddr = mmap(bufferHandle->virAddr, bufferHandle->size, PROT_READ|PROT_WRITE, MAP_SHARED, bufferHandle->fd, 0);
    if (mappedAddr == MAP_FAILED) {
        // mmap failed
    }
    
  5. 将生产的内容写入OHNativeWindowBuffer

    static uint32_t value = 0x00;
    value++;
    uint32_t *pixel = static_cast<uint32_t *>(mappedAddr); // 使用mmap获取到的地址来访问内存
    for (uint32_t x = 0; x < width; x++) {
        for (uint32_t y = 0;  y < height; y++) {
            *pixel++ = value;
        }
    }
    
  6. 提交OHNativeWindowBuffer到图形队列

    // 设置刷新区域,如果Region中的Rect为nullptr,或者rectNumber为0,则认为OHNativeWindowBuffer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);
    
  7. 取消内存映射munmap

    // 内存使用完记得去掉内存映射
    int result = munmap(mappedAddr, bufferHandle->size);
    if (result == -1) {
        // munmap failed
    }
    

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