HarmonyOS：NativeWindow 开发指导

场景介绍

NativeWindow是HarmonyOS本地平台化窗口，表明图形行列的出产者端。开发者能够经过NativeWindow接口进行请求和提交Buffer，配置Buffer特点信息。

针对NativeWindow，常见的开发场景如下：

●经过NativeWindow供给的NativeAPI接口请求图形Buffer，并将出产图形内容写入图形Buffer，终究提交Buffer到图形行列

●在适配EGL层的eglswapbuffer接口时，进行请求和提交Buffer

接口阐明

具体的接口阐明请参考native_window。

开发过程

以下过程描绘了在HarmonyOS中怎么运用NativeWindow供给的NativeAPI接口，请求图形Buffer，并将出产图形内容写入图形Buffer后，终究提交Buffer到图形行列。

增加动态链接库

CMakeLists.txt中增加以下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供给的接口中获取OHNativeWindow，下面供给一份代码示例。XComponent模块的具体运用方法请参考XComponent开发辅导。

a. 在xxx.ets中增加一个XComponent组件。

XComponent({id:'xcomponentId',type:'surface',libraryname:'entry'})
.width(360)
.height(360)

b. 在nativec 层获取NativeXComponent。

napi_valueexportInstance=nullptr;
//用来解分出被wrap了NativeXComponent指针的特点
napi_get_named_property(env,exports,OH_NATIVE_XCOMPONENT_OBJ,&exportInstance);
OH_NativeXComponent*nativeXComponent=nullptr;
//经过napi_unwrap接口，解分出NativeXComponent的实例指针
napi_unwrap(env,exportInstance,reinterpret_cast<void**>(&nativeXComponent));
//获取XComponentId
charidStr[OH_XCOMPONENT_ID_LEN_MAX 1]={};
uint64_tidSize=OH_XCOMPONENT_ID_LEN_MAX 1;
OH_NativeXComponent_GetXComponentId(nativeXComponent,idStr,&idSize);

c. 界说OH_NativeXComponent_Callback。

//界说回调函数
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);
    //...
}

//初始化OH_NativeXComponent_Callback
OH_NativeXComponent_Callbackcallback;
callback.OnSurfaceCreated=OnSurfaceCreatedCB;
callback.OnSurfaceChanged=OnSurfaceChangedCB;
callback.OnSurfaceDestroyed=OnSurfaceDestroyedCB;
callback.DispatchTouchEvent=DispatchTouchEventCB;

d. 将OH_NativeXComponent_Callback注册给NativeXComponent。

//注册回调函数
OH_NativeXComponent_RegisterCallback(nativeXComponent,&callback);

2. 设置OHNativeWindowBuffer的特点。运用OH_NativeWindow_NativeWindowHandleOpt设置OHNativeWindowBuffer的特点。

//设置OHNativeWindowBuffer的宽高
int32_tcode=SET_BUFFER_GEOMETRY;
int32_twidth=0x100;
int32_theight=0x100;
//这里的nativeWindow是从上一过程中的回调函数中获得的
int32_tret=OH_NativeWindow_NativeWindowHandleOpt(nativeWindow,code,width,height);

3. 从图形行列请求OHNativeWindowBuffer。

OHNativeWindowBuffer*buffer=nullptr;
intfenceFd;
//经过OH_NativeWindow_NativeWindowRequestBuffer获取OHNativeWindowBuffer实例
OH_NativeWindow_NativeWindowRequestBuffer(nativeWindow,&buffer,&fenceFd);
//经过OH_NativeWindow_GetBufferHandleFromNative获取buffer的handle
BufferHandle*bufferHandle=OH_NativeWindow_GetBufferHandleFromNative(buffer);

4. 内存映射mmap。

#include<sys/mman.h>
//运用体系接口mmap将bufferHandle对应的共享内存映射到用户空间，能够经过映射出来的虚拟地址向bufferHandle中写入图画数据
//bufferHandle->virAddr是bufferHandle在共享内存中的起始地址，bufferHandle->size是bufferHandle在共享内存中的内存占用大小
void*mappedAddr= mmap(bufferHandle->virAddr,bufferHandle->size,PROT_READ|PROT_WRITE,MAP_SHARED,bufferHandle->fd, 0);
if (mappedAddr==MAP_FAILED) {
    //mmapfailed
}

5. 将出产的内容写入OHNativeWindowBuffer。

static uint32_tvalue= 0x00;
value  ;
uint32_t *pixel= static_cast<uint32_t*>(mappedAddr); //运用mmap获取到的地址来访问内存
for (uint32_tx= 0;x<width;x  ) {
    for (uint32_ty= 0;y<height;y  ) {
        *pixel   =value;
    }
}

6. 提交OHNativeWindowBuffer到图形行列。

//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。
Regionregion{nullptr, 0};
//经过OH_NativeWindow_NativeWindowFlushBuffer提交给消费者运用，例如：显现在屏幕上。
OH_NativeWindow_NativeWindowFlushBuffer(nativeWindow,buffer,fenceFd,region);

7. 撤销内存映射munmap。

//内存运用完记得去掉内存映射
intresult=munmap(mappedAddr,bufferHandle->size);
if(result==-1){
//munmapfailed
}