CoCreateInstance of IWICImagingFactory

问题

I am running Visual Studio 2012 on my Windows 7 machine.

When I run the SimpleDirect2dApplication found here : http://technet.microsoft.com/en-us/subscriptions/dd940321%28v=vs.85%29.aspx

    hr = CoCreateInstance(
    CLSID_WICImagingFactory,
    NULL,
    CLSCTX_INPROC_SERVER,
    IID_PPV_ARGS(&m_pWICFactory)
    );

the CoCreateInstance fails with a "Class Not Registered" and the ptr to the factory is 0.

Any help would be appreciated.

回答1:

According to an answer in a Microsoft's forum a breaking change in the Windows SDK 8.0 requires you to define _WIN32_WINNT to 0x0600 for backward compatibility with Windows Vista or to 0x0601 for backward compatibily with Windows 7.

回答2:

Here's the code I use to handle WIC creation for both WIC and WIC2 scenarios:

namespace
{
    bool g_WIC2 = false;

    BOOL WINAPI InitializeWICFactory(PINIT_ONCE, PVOID, PVOID *ifactory) noexcept
    {
    #if (_WIN32_WINNT >= _WIN32_WINNT_WIN8) || defined(_WIN7_PLATFORM_UPDATE)
        HRESULT hr = CoCreateInstance(
            CLSID_WICImagingFactory2,
            nullptr,
            CLSCTX_INPROC_SERVER,
            __uuidof(IWICImagingFactory2),
            ifactory
        );

        if (SUCCEEDED(hr))
        {
            // WIC2 is available on Windows 10, Windows 8.x, and Windows 7 SP1 with KB 2670838 installed
            g_WIC2 = true;
            return TRUE;
        }
        else
        {
            hr = CoCreateInstance(
                CLSID_WICImagingFactory1,
                nullptr,
                CLSCTX_INPROC_SERVER,
                __uuidof(IWICImagingFactory),
                ifactory
            );
            return SUCCEEDED(hr) ? TRUE : FALSE;
        }
    #else
        return SUCCEEDED(CoCreateInstance(
            CLSID_WICImagingFactory,
            nullptr,
            CLSCTX_INPROC_SERVER,
            __uuidof(IWICImagingFactory),
            ifactory)) ? TRUE : FALSE;
    #endif
    }
}

bool IsWIC2() noexcept
{
    return g_WIC2;
}

IWICImagingFactory* GetWIC() noexcept
{
    static INIT_ONCE s_initOnce = INIT_ONCE_STATIC_INIT;

    IWICImagingFactory* factory = nullptr;
    if (!InitOnceExecuteOnce(
        &s_initOnce,
        InitializeWICFactory,
        nullptr,
        reinterpret_cast<LPVOID*>(&factory)))
    {
        return nullptr;
    }
    return factory;
}

This handles creating the factory once from any thread. You use it by just calling:

auto pWIC = GetWIC();
if (!pWIC)
    // error

For those few cases where you care about WIC vs. WIC2, you use IsWIC2:

if (targetFormat && memcmp(&guidContainerFormat, &GUID_ContainerFormatBmp, sizeof(WICPixelFormatGUID)) == 0 && IsWIC2())
{
    // Opt-in to the WIC2 support for writing 32-bit Windows BMP files with an alpha channel
    PROPBAG2 option = {};
    option.pstrName = const_cast<wchar_t*>(L"EnableV5Header32bppBGRA");

    VARIANT varValue;
    varValue.vt = VT_BOOL;
    varValue.boolVal = VARIANT_TRUE;
    (void)props->Write(1, &option, &varValue);
}

I had use a C++11 lambda for this code in the past, but clang/LLVM doesn't like it so much.

回答3:

using this

#if defined(CLSID_WICImagingFactory)
#undef CLSID_WICImagingFactory
#endif

and then you may pass this

Refer: http://skia.googlecode.com/svn/trunk/src/ports/SkImageDecoder_WIC.cpp

来源：https://stackoverflow.com/questions/14799179/cocreateinstance-of-iwicimagingfactory

标签

c++

directx

direct2d