在析构函数中调用继承的IUnknown :: Release()

Question

为什么在析构函数中的IWICImagingFactory对象上调用继承的IUnknown :: Release()函数会导致在对象的虚函数表(__vfptr)中显示每个条目的"CXX0030:错误:无法计算表达式"？

这是参考我发布的早期问题,但我已经意识到问题只发生在析构函数中.虚拟功能表在我检查过的任何其他地方都有效.但是,一旦在析构函数中,所有条目都显示CXX0030错误,并且尝试调用继承的IUknown :: Release()失败.

编辑:这是一些代码来演示:

HRESULT DemoApp::CreateDeviceIndependentResources()
{
HRESULT hr;


hr = D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, &mpDirect2DFactory);


if (SUCCEEDED(hr))
{
    hr = CoCreateInstance(
        CLSID_WICImagingFactory,
        NULL,
        CLSCTX_INPROC_SERVER,
        IID_PPV_ARGS(&mpWICFactory)
        );
}

//CoCreateInstance returns S_OK.
//Other unrelated code here.
}

HRESULT DemoApp::CreateDeviceResources()
{
HRESULT hr;
//Other unrelated code here for creating device-dependant resources.
//mpBackgroundBitmap is a ID2D1Bitmap*.
    if(SUCCEEDED(hr))
    {
        hr = LoadBitmapFromFile(
            mpRenderTarget,
            mpWICFactory,
            L".\\background.png",
            0,
            0,
            &mpBackgroundBitmap);
    }
}


//The below LoadBitmapFromFile() code is taken directly from an MSDN sample.
//I didn't write it.

HRESULT DemoApp::LoadBitmapFromFile(
ID2D1RenderTarget *pRenderTarget,
IWICImagingFactory *pIWICFactory,
PCWSTR uri,
UINT destinationWidth,
UINT destinationHeight,
ID2D1Bitmap **ppBitmap
)
{
IWICBitmapDecoder *pDecoder = NULL;
IWICBitmapFrameDecode *pSource = NULL;
IWICStream *pStream = NULL;
IWICFormatConverter *pConverter = NULL;
IWICBitmapScaler *pScaler = NULL;

HRESULT hr = pIWICFactory->CreateDecoderFromFilename(
    uri,
    NULL,
    GENERIC_READ,
    WICDecodeMetadataCacheOnLoad,
    &pDecoder
    );

if (SUCCEEDED(hr))
{
    // Create the initial frame.
    hr = pDecoder->GetFrame(0, &pSource);
}
if (SUCCEEDED(hr))
{

    // Convert the image format to 32bppPBGRA
    // (DXGI_FORMAT_B8G8R8A8_UNORM + D2D1_ALPHA_MODE_PREMULTIPLIED).
    hr = pIWICFactory->CreateFormatConverter(&pConverter);

}


if (SUCCEEDED(hr))
{
    // If a new width or height was specified, create an
    // IWICBitmapScaler and use it to resize the image.
    if (destinationWidth != 0 || destinationHeight != 0)
    {
        UINT originalWidth, originalHeight;
        hr = pSource->GetSize(&originalWidth, &originalHeight);
        if (SUCCEEDED(hr))
        {
            if (destinationWidth == 0)
            {
                FLOAT scalar = static_cast<FLOAT>(destinationHeight) / static_cast<FLOAT>(originalHeight);
                destinationWidth = static_cast<UINT>(scalar * static_cast<FLOAT>(originalWidth));
            }
            else if (destinationHeight == 0)
            {
                FLOAT scalar = static_cast<FLOAT>(destinationWidth) / static_cast<FLOAT>(originalWidth);
                destinationHeight = static_cast<UINT>(scalar * static_cast<FLOAT>(originalHeight));
            }

            hr = pIWICFactory->CreateBitmapScaler(&pScaler);
            if (SUCCEEDED(hr))
            {
                hr = pScaler->Initialize(
                        pSource,
                        destinationWidth,
                        destinationHeight,
                        WICBitmapInterpolationModeCubic
                        );
            }
            if (SUCCEEDED(hr))
            {
                hr = pConverter->Initialize(
                    pScaler,
                    GUID_WICPixelFormat32bppPBGRA,
                    WICBitmapDitherTypeNone,
                    NULL,
                    0.f,
                    WICBitmapPaletteTypeMedianCut
                    );
            }
        }
    }
    else // Don't scale the image.
    { 
        hr = pConverter->Initialize(
            pSource,
            GUID_WICPixelFormat32bppPBGRA,
            WICBitmapDitherTypeNone,
            NULL,
            0.f,
            WICBitmapPaletteTypeMedianCut
            );
    }
}
if (SUCCEEDED(hr))
{

    // Create a Direct2D bitmap from the WIC bitmap.
    hr = pRenderTarget->CreateBitmapFromWicBitmap(
        pConverter,
        NULL,
        ppBitmap
        );
}

SafeRelease(&pDecoder);
SafeRelease(&pSource);
SafeRelease(&pStream);
SafeRelease(&pConverter);
SafeRelease(&pScaler);

return hr;
}

//Now I call SafeRelease() in my destructor and the virtual function table entires are showing the error.
DemoApp::~DemoApp()
{
SafeRelease(&mpDirect2DFactory);
SafeRelease(&mpWICFactory); //here is the problem apparently
SafeRelease(&mpDWriteFactory); 
SafeRelease(&mpRenderTarget);
SafeRelease(&mpBackgroundBitmap);

}

//SafeRelease is defined as:
template<class Interface>
inline void SafeRelease(Interface** ppInterfaceToRelease)
{
if(*ppInterfaceToRelease != NULL)
{
    (*ppInterfaceToRelease)->Release();
    (*ppInterfaceToRelease) = NULL;
        }

}

问题是当我在WICFactory对象上调用SafeRelease()时,我得到:DemoApp.exe中0x0024e135的第一次机会异常:0xC0000005:访问冲突读取位置0x6d5c28f0.DemoApp.exe中0x0024e135处的未处理异常:0xC0000005:访问冲突读取位置0x6d5c28f0.

Answer 1

我最近也在努力解决这个问题.问题在于创建和释放分别IWICImagingFactory依赖于CoInitialize/ CoUninitialize被调用之前和之后.在您的应用程序中,很可能在析构函数中释放CoUninitialize()之前调用它IWICImagingFactory,这会导致崩溃.请注意,这ID2D1RenderTarget似乎并没有受到影响,并且在CoUninitialize()调用后仍然可以释放.

删除呼叫CoUninitialize()从RunMessageLoop()或者是任何一个是,把它释放调用后在析构函数和碰撞吸能就会消失.