PropVariantToInt16 function (propvarutil.h)

Extracts an Int16 property value of a PROPVARIANT structure.

Syntax

PSSTDAPI PropVariantToInt16(
  [in]  REFPROPVARIANT propvarIn,
  [out] SHORT          *piRet
);

Parameters

[in] propvarIn

Type: REFPROPVARIANT

Reference to a source PROPVARIANT structure.

[out] piRet

Type: SHORT*

When this function returns, contains the extracted property value if one exists; otherwise, 0.

Return value

Type: HRESULT

If this function succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

This helper function is used in places where the calling application expects a PROPVARIANT to hold an Int16 value. For instance, an application obtaining values from a property store can use this to safely extract the Int16 value for Int16 properties.

If the source PROPVARIANT has type VT_I2, this helper function extracts the Int16 value. Otherwise, it attempts to convert the value in the PROPVARIANT structure into an Int16. If a conversion is not possible, PropVariantToInt16 will return a failure code and set piRet to 0. See PropVariantChangeType for a list of possible conversions. Of note, VT_EMPTY is successfully converted to 0.

Examples

The following example, to be included as part of a larger program, demonstrates how to use PropVariantToInt16 to access an Int16 value in a PROPVARIANT.

// IPropertyStore *ppropstore;

// Assume variable ppropstore is initialized and valid

PROPVARIANT propvar = {0};

HRESULT hr = ppropstore->GetValue(PKEY_Image_ResolutionUnit, &propvar);

if (SUCCEEDED(hr))

{

     // PKEY_Image_ResolutionUnit is expected to produce a VT_I2 or VT_EMPTY value.

     // PropVariantToInt16 will convert VT_EMPTY to 0.

     INT16 iUnit;

     hr = PropVariantToInt16(propvar, & iUnit);

     if (SUCCEEDED(hr))

     {

             // iUnit is now valid

     }

     else

     {

             // iUnit is always 0

     }

     PropVariantClear(&propvar);

}

Requirements