我想实现一个包装 char* 缓冲区的 C++ WinRT IBuffer,因此我可以将它与接受 IBuffer^ 参数的 WinRT WriteAsync/ReadAsync 操作一起使用。
编辑 1(说明)
我想避免数据复制。
最佳答案
大部分复制自http://jeremiahmorrill.wordpress.com/2012/05/11/http-winrt-client-for-c/但适合直接包装我自己的 byte[]:
NativeBuffer.h:
#pragma once
#include <wrl.h>
#include <wrl/implements.h>
#include <windows.storage.streams.h>
#include <robuffer.h>
#include <vector>
// todo: namespace
class NativeBuffer :
public Microsoft::WRL::RuntimeClass<Microsoft::WRL::RuntimeClassFlags<Microsoft::WRL::RuntimeClassType::WinRtClassicComMix>,
ABI::Windows::Storage::Streams::IBuffer,
Windows::Storage::Streams::IBufferByteAccess>
{
public:
virtual ~NativeBuffer()
{
}
STDMETHODIMP RuntimeClassInitialize(byte *buffer, UINT totalSize)
{
m_length = totalSize;
m_buffer = buffer;
return S_OK;
}
STDMETHODIMP Buffer(byte **value)
{
*value = m_buffer;
return S_OK;
}
STDMETHODIMP get_Capacity(UINT32 *value)
{
*value = m_length;
return S_OK;
}
STDMETHODIMP get_Length(UINT32 *value)
{
*value = m_length;
return S_OK;
}
STDMETHODIMP put_Length(UINT32 value)
{
m_length = value;
return S_OK;
}
private:
UINT32 m_length;
byte *m_buffer;
};
创建 IBuffer:
Streams::IBuffer ^CreateNativeBuffer(LPVOID lpBuffer, DWORD nNumberOfBytes)
{
Microsoft::WRL::ComPtr<NativeBuffer> nativeBuffer;
Microsoft::WRL::Details::MakeAndInitialize<NativeBuffer>(&nativeBuffer, (byte *)lpBuffer, nNumberOfBytes);
auto iinspectable = (IInspectable *)reinterpret_cast<IInspectable *>(nativeBuffer.Get());
Streams::IBuffer ^buffer = reinterpret_cast<Streams::IBuffer ^>(iinspectable);
return buffer;
}
以及读取数据的调用(lpBuffer是byte[]):
Streams::IBuffer ^buffer = CreateNativeBuffer(lpBuffer, nNumberOfbytes);
create_task(randomAccessStream->ReadAsync(buffer, (unsigned int)nNumberOfBytesToRead, Streams::InputStreamOptions::None)).wait();
我不太确定 ComPtr 是否需要清理,因此欢迎任何有关内存管理的建议。
关于c++ - 如何在 C++ 中将 char* 缓冲区包装在 WinRT IBuffer 中,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/10520335/