IFilter interface (filter.h)
Note
Indexing Service is no longer supported as of Windows XP and is unavailable for use as of Windows 8. Instead, use Windows Search for client side search and Microsoft Search Server Express for server side search.
Scans documents for text and properties (also called attributes). It extracts chunks of text from these documents, filtering out embedded formatting and retaining information about the position of the text. It also extracts chunks of values, which are properties of an entire document or of well-defined parts of a document. IFilter provides the foundation for building higher-level applications such as document indexers and application-independent viewers.
For introductory information about how the IFilter interface works with documents and document properties, see Properties of Documents. For a synopsis and an example of how the IFilter interface processes a document, see Property Filtering and Property Indexing.
Inheritance
The IFilter interface inherits from the IUnknown interface. IFilter also has these types of members:
Methods
The IFilter interface has these methods.
| IFilter::BindRegion Retrieves an interface representing the specified portion of object. Currently reserved for future use. |
| IFilter::GetChunk Positions the filter at the beginning of the next chunk, or at the first chunk if this is the first call to the GetChunk method, and returns a description of the current chunk. |
| IFilter::GetText Retrieves text (text-type properties) from the current chunk, which must have a CHUNKSTATE enumeration value of CHUNK_TEXT. |
| IFilter::GetValue Retrieves a value (internal value-type property) from a chunk, which must have a CHUNKSTATE enumeration value of CHUNK_VALUE. |
| IFilter::Init Initializes a filtering session. |
Remarks
IFilter components for Indexing Service run in the Local Security context and should be written to manage buffers and to stack correctly. All string copies must have explicit checks to guard against buffer overruns. You should always verify the allocated size of the buffer and test the size of the data against the size of the buffer.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Target Platform | Windows |
| Header | filter.h |