Verifying Support of Query Types
The DirectX 9.0 runtime must verify which query types that a driver supports before any asynchronous query operations can be performed. To verify the number of query types that the driver supports, the runtime sends a GetDriverInfo2 request using the D3DGDI2_TYPE_GETD3DQUERYCOUNT value. If the driver does not support any query types, it returns zero in the dwNumQueries member of the DD_GETD3DQUERYCOUNTDATA structure for this request.
To receive information about each supported query type, the runtime sends a GetDriverInfo2 request using the D3DGDI2_TYPE_GETD3DQUERY value for each type. The driver then returns information about the query type in a DD_GETD3DQUERYDATA structure. For more information about GetDriverInfo2, see Supporting GetDriverInfo2.