使用DirectX捕获屏幕

问题描述

我知道如何使用GDI捕获屏幕，但是它很慢（它几乎不捕获10 fps）

I know how to use GDI to capture screen, however it is very slow (it barely captures 10 fps)

我读过DirectX提供最好的速度。但在我开始学习DirectX之前，我想测试一个示例，看看它是否真的那么快。

I have read that DirectX offers the best speed. But before I start learning DirectX I wanted to test a sample to see if it is really that fast.

我发现这个（Windows中包含的成像库已有很长时间了）保存图像（因此，需要安装需要安装旧DirectX SDK的着名的D3DXSaveSurfaceToFile）：

To compile this, you will also need WIC (an imaging library included with Windows for quite a time now) to save an image (so you don't need the famous D3DXSaveSurfaceToFile that require old DirectX SDKs to be installed):

  HRESULT SavePixelsToFile32bppPBGRA(UINT width, UINT height, UINT stride, LPBYTE pixels, LPWSTR filePath, const GUID &format)
  {
    if (!filePath || !pixels)
      return E_INVALIDARG;

    HRESULT hr = S_OK;
    IWICImagingFactory *factory = nullptr;
    IWICBitmapEncoder *encoder = nullptr;
    IWICBitmapFrameEncode *frame = nullptr;
    IWICStream *stream = nullptr;
    GUID pf = GUID_WICPixelFormat32bppPBGRA;
    BOOL coInit = CoInitialize(nullptr);

    HRCHECK(CoCreateInstance(CLSID_WICImagingFactory, nullptr, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&factory)));
    HRCHECK(factory->CreateStream(&stream));
    HRCHECK(stream->InitializeFromFilename(filePath, GENERIC_WRITE));
    HRCHECK(factory->CreateEncoder(format, nullptr, &encoder));
    HRCHECK(encoder->Initialize(stream, WICBitmapEncoderNoCache));
    HRCHECK(encoder->CreateNewFrame(&frame, nullptr)); // we don't use options here
    HRCHECK(frame->Initialize(nullptr)); // we dont' use any options here
    HRCHECK(frame->SetSize(width, height));
    HRCHECK(frame->SetPixelFormat(&pf));
    HRCHECK(frame->WritePixels(height, stride, stride * height, pixels));
    HRCHECK(frame->Commit());
    HRCHECK(encoder->Commit());

  cleanup:
    RELEASE(stream);
    RELEASE(frame);
    RELEASE(encoder);
    RELEASE(factory);
    if (coInit) CoUninitialize();
    return hr;
  }

我使用的一些宏：

  #define WIDEN2(x) L ## x
  #define WIDEN(x) WIDEN2(x)
  #define __WFILE__ WIDEN(__FILE__)
  #define HRCHECK(__expr) {hr=(__expr);if(FAILED(hr)){wprintf(L"FAILURE 0x%08X (%i)\n\tline: %u file: '%s'\n\texpr: '" WIDEN(#__expr) L"'\n",hr, hr, __LINE__,__WFILE__);goto cleanup;}}
  #define RELEASE(__p) {if(__p!=nullptr){__p->Release();__p=nullptr;}}

：对于Windows 8+客户端，应该删除所有这些（WIC除外）以支持。

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