Sample extension unit plug-in DLL

Artikel
12/15/2021

Important

The content and sample code in this topic is outdated and currently unsupported. It may not work with the current driver development toolchain.

This topic contains sample code for an Extension Unit plug-in DLL that exposes a COM API on top of a KS property set.

The sample defines a class called CExtension, which derives from CNodeControl. The implementation of the CNodeControl class is also provided later. CNodeControl derives from the Microsoft-supplied IKsNodeControl interface, which is defined in Vidcap.h.

Vidcap.ax uses IKsNodeControl to inform the plug-in of the extension node ID and provide it with an instance of IKsControl. Specifically, the plug-in receives this information through calls to CExtension::put_NodeId and CExtension::put_KsControl. You can find possible implementations of these methods later in this topic for the parent class CNodeControl.

Vidcap.h appears in the Summer 2004 DirectX SDK through the February 2005 DirectX SDK. When installing these packages, you must install the Extras to obtain Vidcap.h.

In Windows Vista and later releases, Vidcap.h is included as part of the Microsoft Windows SDK.

Include the following code in the class header file, arbitrarily named Xuproxy.h:

#include <ks.h>
#include <ksproxy.h>
#include <C:\Program Files\Microsoft DirectX 9.0 SDK (February 2005)\Extras\DirectShow\Include\vidcap.h>
#include <C:\Program Files\Microsoft DirectX 9.0 SDK (February 2005)\Extras\DirectShow\Include\ksmedia.h>

DEFINE_GUID(CLSID_ExtensionUnit, 0xzzzzzzzz, 0xzzzz, 0xzzzz, 0xzz, 0xzz, 0xzz, 0xzz, 0xzz, 0xzz, 0xzz, 0xzz);

class CNodeControl :
    public IKsNodeControl
{
public:
    STDMETHOD(put_NodeId) (DWORD dwNodeId);
    STDMETHOD(put_KsControl) (PVOID pKsControl);

    DWORD m_dwNodeId;
    CComPtr<IKsControl> m_pKsControl;
};

class CExtension :
   public IExtensionUnit,
   public CComObjectRootEx<CComObjectThreadModel>,
   public CComCoClass<CExtension, &CLSID_ExtensionUnit>,
   public CNodeControl
{
   public:

   CExtension();
   STDMETHOD(FinalConstruct)();

   BEGIN_COM_MAP(CExtension)
      COM_INTERFACE_ENTRY(IKsNodeControl)
      COM_INTERFACE_ENTRY(IExtensionUnit)
   END_COM_MAP()

   DECLARE_PROTECT_FINAL_CONSTRUCT()
   DECLARE_NO_REGISTRY()
   DECLARE_ONLY_AGGREGATABLE(CExtension)

   // IExtensionUnit
   public:
   STDMETHOD (get_Info)(
      ULONG ulSize,
      BYTE pInfo[]);
   STDMETHOD (get_InfoSize)(
      ULONG *pulSize);
   STDMETHOD (get_PropertySize)(
      ULONG PropertyId,
      ULONG *pulSize);
   STDMETHOD (get_Property)(
      ULONG PropertyId,
      ULONG ulSize,
      BYTE pValue[]);
   STDMETHOD (put_Property)(
      ULONG PropertyId,
      ULONG ulSize,
      BYTE pValue[]);
   STDMETHOD (get_PropertyRange)(
      ULONG PropertyId,
      ULONG ulSize,
      BYTE pMin[],
      BYTE pMax[],
      BYTE pSteppingDelta[],
      BYTE pDefault[]);
};

#define STATIC_PROPSETID_VIDCAP_EXTENSION_UNIT \
   0xXXXXXXXX,0xXXXX,0xXXXX,0xXX,0xXX,0xXX,0xXX,0xXX,0xXX,0xXX,0xXX
DEFINE_GUIDSTRUCT("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX", \
   PROPSETID_VIDCAP_EXTENSION_UNIT);
#define PROPSETID_VIDCAP_EXTENSION_UNIT \
   DEFINE_GUIDNAMED(PROPSETID_VIDCAP_EXTENSION_UNIT)

Implement the two virtual methods from IKsNodeControl in CNodeControl. These methods are then inherited by instances of the CExtension class.

The following code is in a source file arbitrarily named Xuproxy.cpp:

STDMETHODIMP
CNodeControl::put_NodeId(
   DWORD dwNodeId)
{
   m_dwNodeId = dwNodeId;
 return S_OK;
}

STDMETHODIMP
CNodeControl::put_KsControl(
   PVOID pKsControl)
{
   HRESULT hr = S_OK;
   IKsControl *pIKsControl;

 if (!pKsControl) return E_POINTER;
    pIKsControl = (IKsControl *) pKsControl;

    if (m_pKsControl) m_pKsControl.Release();
 hr = pIKsControl->QueryInterface(__uuidof(IKsControl),
       (void **) &m_pKsControl);

    return hr;
}

Also include implementations of CExtension's methods in the same Xuproxy.cpp file:

CExtension::CExtension()
{
    m_pKsControl = NULL;
}

STDMETHODIMP
CExtension::FinalConstruct()
{
    if (m_pOuterUnknown == NULL ) return E_FAIL;
    return S_OK;
}

STDMETHODIMP
CExtension::get_InfoSize(
    ULONG *pulSize)
{
    HRESULT hr = S_OK;
    ULONG ulBytesReturned;
    KSP_NODE ExtensionProp;

    if (!pulSize) return E_POINTER;

    ExtensionProp.Property.Set = PROPSETID_VIDCAP_EXTENSION_UNIT;
    ExtensionProp.Property.Id = KSPROPERTY_EXTENSION_UNIT_INFO;
    ExtensionProp.Property.Flags = KSPROPERTY_TYPE_GET |
                                   KSPROPERTY_TYPE_TOPOLOGY;
    ExtensionProp.NodeId = m_dwNodeId;

 hr = m_pKsControl->KsProperty(
        (PKSPROPERTY) &ExtensionProp,
        sizeof(ExtensionProp),
        NULL,
        0,
        &ulBytesReturned);

    if (hr == HRESULT_FROM_WIN32(ERROR_MORE_DATA))
    {
        *pulSize = ulBytesReturned;
        hr = S_OK;
    }

 return hr;
}


STDMETHODIMP
CExtension::get_Info(
    ULONG ulSize,
    BYTE pInfo[])
{
    HRESULT hr = S_OK;
    KSP_NODE ExtensionProp;
    ULONG ulBytesReturned;

    ExtensionProp.Property.Set = PROPSETID_VIDCAP_EXTENSION_UNIT;
    ExtensionProp.Property.Id = KSPROPERTY_EXTENSION_UNIT_INFO;
    ExtensionProp.Property.Flags = KSPROPERTY_TYPE_GET |
                                   KSPROPERTY_TYPE_TOPOLOGY;
    ExtensionProp.NodeId = m_dwNodeId;

    hr = m_pKsControl->KsProperty(
        (PKSPROPERTY) &ExtensionProp,
 sizeof(ExtensionProp),
        (PVOID) pInfo,
        ulSize,
        &ulBytesReturned);

 return hr;
}


STDMETHODIMP
CExtension::get_PropertySize(
    ULONG PropertyId,
    ULONG *pulSize)
{
    HRESULT hr = S_OK;
    ULONG ulBytesReturned;
    KSP_NODE ExtensionProp;

 if (!pulSize) return E_POINTER;

    ExtensionProp.Property.Set = PROPSETID_VIDCAP_EXTENSION_UNIT;
    ExtensionProp.Property.Id = PropertyId;
    ExtensionProp.Property.Flags = KSPROPERTY_TYPE_GET |
                                   KSPROPERTY_TYPE_TOPOLOGY;
    ExtensionProp.NodeId = m_dwNodeId;

    hr = m_pKsControl->KsProperty(
        (PKSPROPERTY) &ExtensionProp,
 sizeof(ExtensionProp),
        NULL,
        0,
        &ulBytesReturned);

 if (hr == HRESULT_FROM_WIN32(ERROR_MORE_DATA))
    {
        *pulSize = ulBytesReturned;
        hr = S_OK;
    }

 return hr;
}

STDMETHODIMP
CExtension::get_Property(
    ULONG PropertyId,
    ULONG ulSize,
    BYTE pValue[])
{
    HRESULT hr = S_OK;
    KSP_NODE ExtensionProp;
    ULONG ulBytesReturned;

    ExtensionProp.Property.Set = PROPSETID_VIDCAP_EXTENSION_UNIT;
    ExtensionProp.Property.Id = PropertyId;
    ExtensionProp.Property.Flags = KSPROPERTY_TYPE_GET |
                                   KSPROPERTY_TYPE_TOPOLOGY;
    ExtensionProp.NodeId = m_dwNodeId;

    hr = m_pKsControl->KsProperty(
        (PKSPROPERTY) &ExtensionProp,
 sizeof(ExtensionProp),
        (PVOID) pValue,
        ulSize,
        &ulBytesReturned);

    return hr;
}

STDMETHODIMP
CExtension::put_Property(
    ULONG PropertyId,
    ULONG ulSize,
    BYTE pValue[])
{
    HRESULT hr = S_OK;
    KSP_NODE ExtensionProp;
    ULONG ulBytesReturned;

    ExtensionProp.Property.Set = PROPSETID_VIDCAP_EXTENSION_UNIT;
    ExtensionProp.Property.Id = PropertyId;
    ExtensionProp.Property.Flags = KSPROPERTY_TYPE_SET |
                                   KSPROPERTY_TYPE_TOPOLOGY;
    ExtensionProp.NodeId = m_dwNodeId;

    hr = m_pKsControl->KsProperty(
        (PKSPROPERTY) &ExtensionProp,
 sizeof(ExtensionProp),
        (PVOID) pValue,
        ulSize,
        &ulBytesReturned);

    return hr;
}

STDMETHODIMP
CExtension::get_PropertyRange(
    ULONG PropertyId,
    ULONG ulSize,
    BYTE pMin[  ],
    BYTE pMax[  ],
    BYTE pSteppingDelta[  ],
    BYTE pDefault[  ])
{
    // IHV may add code here, current stub just returns S_OK
    HRESULT hr = S_OK;
    return hr;
}

CExtension::CExtension()
{
    m_pKsControl = NULL;
}

STDMETHODIMP
CExtension::FinalConstruct()
{
    if (m_pOuterUnknown == NULL) return E_FAIL;
    return S_OK;
}

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Sample extension unit plug-in DLL

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