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我有两个任务：

a) 将数码相机与其他 MTP 设备区分开来，由 IPortableDeviceManager::GetDeviceList 获得；

b) 我想使用 Setup API 查找已连接的数码相机。我的想法是先获取所有 USB 设备：

SetupDiGetClassDevs( &GUID_DEVINTERFACE_USB_DEVICE, 0, 0, DIGCF_DEVICEINTERFACE | DIGCF_PRESENT);

但是在这样做之后，我已经没有想法了。具体来说，我不知道如何获取特定 USB 设备的 USB 接口描述符。我的意思是 USB 接口，而不是设置 API 中所谓的接口。

提前致谢。

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1 回答 1

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以下是使用 WPD 完成的方法（假设您已经打开了一个名为 wpdDev 的设备）：

    IPortableDeviceCapabilities* pCaps = 0;
    IPortableDevice* pWpdDev = wpdDev.getWpdDev();
    hr = pWpdDev->Capabilities(&pCaps);
    if (hr != S_OK || !pCaps)
    {
        Logger() << "Failed to obtain capabilities for device" << CString::fromUtf16(deviceId).toUtf8().getData();
        continue;
    }
    IPortableDevicePropVariantCollection* pCategories = 0;
    hr = pCaps->GetFunctionalCategories(&pCategories);
    if (hr != S_OK || !pCategories)
    {
        Logger() << "Failed to obtain functional categories for device" << CString::fromUtf16(deviceId).toUtf8().getData();
        continue;
    }
    DWORD numCategories = 0;
    hr = pCategories->GetCount(&numCategories);
    if (hr != S_OK || !numCategories)
    {
        Logger() << "Failed to obtain functional categories for device" << CString::fromUtf16(deviceId).toUtf8().getData();
        continue;
    }
    bool isCamera = wpdDev.vendor() == CANON_VENDOR_ID;
    //Просматриваем все категории и проверяем, может ли устройство выполнять функции камеры
    for (size_t idx = 0; idx < numCategories; ++idx)
    {
        PROPVARIANT pv = {0};
        PropVariantInit(&pv);
        hr = pCategories->GetAt(idx, &pv);
        if (hr == S_OK)
        // We have a functional category.  It is assumed that
        // functional categories are returned as VT_CLSID
        // VarTypes.
            if ((pv.puuid != NULL) && (pv.vt == VT_CLSID))
                if (IsEqualGUID(WPD_FUNCTIONAL_CATEGORY_STILL_IMAGE_CAPTURE, *(pv.puuid)))
                    isCamera = true;
        PropVariantClear(&pv);
    }
于 2011-09-08T12:53:00.773 回答