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前面的一篇博文中总结了开发Windows Thumbnail Handler的一些经验。在公司实际项目中，需要同时针对图片和视频实现缩略图。同时还要在图片和视频文件的顶部加上LOGO。像如下这样的：
/**
* Decode the Base64-encoded string to get logo resources.
*/
HRESULT RecipeThumbnailProvider::GetLogoFromString(LPCWSTR encodedString, UINT* width, UINT* height, PBYTE* rawPixels)
{
IStream* pImageStream = NULL;
HRESULT hr = E_FAIL;
DWORD dwDecodedImageSize = 0;
DWORD dwSkipChars = 0;
DWORD dwActualFormat = 0;
if (CryptStringToBinary(encodedString, NULL, CRYPT_STRING_BASE64, NULL, &dwDecodedImageSize, &dwSkipChars, &dwActualFormat))
{
BYTE* pbDecodedImage = static_cast<BYTE*>(LocalAlloc(LPTR, dwDecodedImageSize));
if (pbDecodedImage)
{
if (CryptStringToBinary(encodedString, lstrlen(encodedString), CRYPT_STRING_BASE64, pbDecodedImage, &dwDecodedImageSize, &dwSkipChars, &dwActualFormat))
{
pImageStream = SHCreateMemStream(pbDecodedImage, dwDecodedImageSize);
if (pImageStream != NULL)
{
IWICImagingFactory* pImageFactory;
hr = CoCreateInstance(CLSID_WICImagingFactory, NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pImageFactory));
LOGINFO(L"CoCreateIntance() returns 0x%x", hr);
if (SUCCEEDED(hr))
{
IWICBitmapDecoder* pDecoder;
hr = pImageFactory->CreateDecoderFromStream(pImageStream, &GUID_VendorMicrosoft, WICDecodeMetadataCacheOnDemand, &pDecoder);
if (SUCCEEDED(hr))
{
IWICBitmapFrameDecode* pBitmapFrameDecode;
hr = pDecoder->GetFrame(0, &pBitmapFrameDecode);
if (SUCCEEDED(hr))
{
IWICBitmapSource* pBitmapSourceConverted = NULL;
WICPixelFormatGUID guidPixelFormatSource;
hr = pBitmapFrameDecode->GetPixelFormat(&guidPixelFormatSource);
if (SUCCEEDED(hr) && (guidPixelFormatSource != GUID_WICPixelFormat24bppBGR))
{
IWICFormatConverter* pFormatConverter;
hr = pImageFactory->CreateFormatConverter(&pFormatConverter);
if (SUCCEEDED(hr))
{
hr = pFormatConverter->Initialize(pBitmapFrameDecode, GUID_WICPixelFormat24bppBGR, WICBitmapDitherTypeNone, NULL, 0, WICBitmapPaletteTypeCustom);
if (SUCCEEDED(hr))
{
hr = pFormatConverter->QueryInterface(&pBitmapSourceConverted);
}
pFormatConverter->Release();
}
}
else
{
hr = pBitmapFrameDecode->QueryInterface(&pBitmapSourceConverted);
}
if (SUCCEEDED(hr))
{
hr = pBitmapSourceConverted->GetSize(width, height);
if (SUCCEEDED(hr))
{
WICRect rect = { 0, 0, *width, *height };
*rawPixels = static_cast<BYTE*>(LocalAlloc(LPTR, (*width)*(*height)*3));
hr = pBitmapSourceConverted->CopyPixels(&rect, (*width) * 3, (*width)*(*height) * 3, *rawPixels);
}
else
{
*width = 0;
*height = 0;
*rawPixels = NULL;
}
pBitmapSourceConverted->Release();
}
pBitmapFrameDecode->Release();
}
pDecoder->Release();
}
pImageFactory->Release();
}
pImageStream->Release();
}
}
}
LocalFree(pbDecodedImage);
}
return hr;
}
当我注册好COM组件开始使用时，在本机上测试简直完美。满以为就这么搞定了，然而并么有。在另外一台Win7机器上测试时，缩略图中并没有出现想象中的LOGO。一看日志文件，发现一直在报：CoCreateInstance()调用返回0x80040154。于是下面的代码都没执行，LOGO资源自然没有加载成功了。那么CoCreateInstance()为啥会返回0x80040154呢？这个代码又意味着什么嗯？从网上的搜索结果来看，0x80040154是表示"Class Not Registered"。也就是说COM类并没有注册，在注册表\HKEY_CLASSES_ROOT\CLSID\下面也就没有类ID了。我们程序中使用了WIC组件来解码图片，那么难道是WIC组件类没有注册吗？
CoCreateInstance调用返回代码0x80040154的一种解决方法
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原文地址：http://www.cnblogs.com/csuftzzk/p/cocreateinstance_failed_0x80040154.html
