InfoTip Interfaces
InfoTip handlers implement two interfaces:
IPersistFile
and IQueryInfo
. We
have discussed IPersistFile
several times already,
most notably in Chapter 5, so we will jump
straight into IQueryInfo
. Let’s examine the
interface definition, which is shown in Example 10.1.
Table 10.1 gives a brief description of each of the
methods.
Example 10-1. IQueryInfo
//------------------------------------------------------ // IQueryInfo //------------------------------------------------------ [ uuid(00021500-0000-0000-C000-000000000046), helpstring("IQueryInfo Interface"), odl ] interface IQueryInfo : IUnknown { HRESULT GetInfoTip([in] DWORD dwFlags, [in,out] LPWSTRVB *ppwszTip); HRESULT GetInfoFlags([in,out] DWORD *pdwFlags); }
Table 10-1. IQueryInfo
IQueryInfo
is a very basic interface that contains
two methods: GetInfoTip
and
GetInfoFlags
. GetInfoFlags
is
not currently used by the shell, so it will not be discussed. That
leaves GetInfoTip
.
GetInfoTip
GetInfoTip
is called by the shell to request an InfoTip string from the handler.
Its syntax is:
HRESULT GetInfoTip( DWORD dwFlags, LPWSTR *ppwszTip );
with the following parameters:
-
dwFlags
[in]
This parameter is not used currently by the shell.-
ppwszTip
[in,
out]
The address of a wide-character ...
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