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KSPROPERTY_ITEM structure

Drivers use the KSPROPERTY_ITEM structure to describe how they support a property in a property set.

Syntax


typedef struct {
  ULONG                   PropertyId;
  union {
    PFNKSHANDLER GetPropertyHandler;
    BOOLEAN      GetSupported;
  };
  ULONG                   MinProperty;
  ULONG                   MinData;
  union {
    PFNKSHANDLER SetPropertyHandler;
    BOOLEAN      SetSupported;
  };
  const KSPROPERTY_VALUES *Values;
  ULONG                   RelationsCount;
  const KSPROPERTY        *Relations;
  PFNKSHANDLER            SupportHandler;
  ULONG                   SerializedSize;
} KSPROPERTY_ITEM, *PKSPROPERTY_ITEM;

Members

PropertyId

Specifies the ID of the property being described.

GetPropertyHandler

Pointer to a minidriver-supplied KStrGetPropertyHandler. If NULL, the property cannot be read. This member is used only by drivers that use the AVStream or Stream class interfaces.

GetSupported

Set to TRUE if this property supports get requests, FALSE if it does not. (The class driver fulfills the request through the SRB_GET_DEVICE_PROPERTY or SRB_GET_STREAM_PROPERTY requests.) This member is used only by minidrivers running under stream class.

MinProperty

Specifies the minimum buffer length to hold the property identifier. This must be at least sizeof(KSPROPERTY).

MinData

Specifies the minimum buffer length to hold the data read from or written to this property.

SetPropertyHandler

Pointer to a minidriver-supplied KStrSetPropertyHandler. If NULL, the property cannot be set. This member is used only by drivers that use the AVStream or Stream class interfaces.

SetSupported

Set to TRUE if this property supports set requests, FALSE if it does not. (The class driver fulfills the request through the SRB_SET_DEVICE_PROPERTY or SRB_SET_STREAM_PROPERTY requests.)

Values

Pointer to a structure of type KSPROPERTY_VALUES. Specifies the acceptable and/or default values for the property. These are the same as the values reported by a driver in response to an IOCTL_KS_PROPERTY request with the KSPROPERTY_TYPE_BASICSUPPORT and KSPROPERTY_TYPE_DEFAULTVALUES flags set.

RelationsCount

Specifies the number of entries in the array pointed to by the Relations member.

Relations

Points to an array of KSPROPERTY structures representing properties related to this one. Two properties are considered related if changing one property may affect the value of the other property. The Flags member of each entry is unused.

SupportHandler

Provide this member only if implementing your own format for raw serialization or raw unserialization. Basic support queries, range queries, and relations queries are automatically handled by AVStream, which returns the relevant values from other members of this KSPROPERTY_ITEM structure.

SerializedSize

Specifies the size of the property when serialized in a KSPROPERTY_TYPE_SERIALIZESET request. This should be zero if the property cannot be serialized. See KSPROPERTY for more information.

Remarks

Stream class minidrivers use KSPROPERTY_ITEM to describe to the client how to fulfill property requests on each property within a set. Handling for the property set as a whole is specified in the KSPROPERTY_SET structure, which contains pointers to arrays of KSPROPERTY_ITEM structures.

The stream class driver handles property requests on behalf of the minidriver. When the stream class driver requires more information from the minidriver, it passes an SRB_XXX request to one of the minidriver's StrMiniReceiveXXXRequest routines. The stream class driver handles the different request types as listed in the following table.

Property request flags valueResponse

KSPROPERTY_TYPE_GET

If GetSupported is TRUE, the stream class driver submits an SRB_GET_DEVICE_PROPERTY or SRB_GET_STREAM_PROPERTY request to the appropriate minidriver StrMiniReceiveXXXRequest routine.

KSPROPERTY_TYPE_SET

If SetSupported is TRUE, the stream class driver submits an SRB_SET_DEVICE_PROPERTY or SRB_SET_STREAM_PROPERTY request to the appropriate minidriver StrMiniReceiveXXXRequest routine.

KSPROPERTY_TYPE_BASICSUPPORT

The stream class driver uses KSPROPERTY_ITEM to obtain the information necessary to fulfill this request. For example, to specify the data type and permitted ranges of the property data, they each use the Values member of this structure.

KSPROPERTY_TYPE_SETSUPPORT

The stream class driver completes the property request IRP as STATUS_SUCCESS only if the driver supplies an entry for the property set within its KSPROPERTY_SET structure.

KSPROPERTY_TYPE_DEFAULTVALUES

The stream class driver uses the Values member of this structure to determine the default values for the property data.

KSPROPERTY_TYPE_RELATIONS

The stream class driver uses the Relations member to determine what properties are related to this property.

 

If the client specifies KSPROPERTY_TYPE_DEFAULTVALUES, the driver uses the data buffer to return a description of its value type, including possibly its allowed range and default value. This flag is similar in result to KSPROPERTY_TYPE_BASICSUPPORT, except that any values returned are those that have been marked with KSPROPERTY_MEMBER_FLAG_DEFAULT in the Flags member of the structure KSPROPERTY_MEMBERSHEADER.

For more information, see KS Properties.

Requirements

Header

Ks.h (include Ks.h)

See also

KSPROPERTY
KSPROPERTY_SET
SRB_GET_DEVICE_PROPERTY
SRB_GET_STREAM_PROPERTY
SRB_SET_DEVICE_PROPERTY
SRB_SET_STREAM_PROPERTY
KSPROPERTY_VALUES

 

 

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