Compressor
and Decompressor Installation and Removal
An
application can use compressors and decompressors that are already installed on
a system running the Microsoft Windows operating system. An application can
also install compressors and decompressors for general or special uses. Most
applications will not need to install or remove compressors or decompressors
because they are usually installed by a setup program. An application might,
however, install a compressor directly or install a function as a compressor.
An
application can install a compressor or decompressor (or a function used as a
compressor or decompressor) by using the ICInstall function. This function
creates an entry in the registry identifying the compressor or decompressor.
Your application or another application can search the registry to determine if
the system contains a compressor or decompressor suitable for its data. Use ICInstall
to install all compression and decompression drivers.
An
application can locate and open an installed compressor or decompressor by
using the ICLocate
and ICOpen
functions. When an application finishes using a compressor or decompressor, it
closes it by using the ICClose function.
An
application can remove the registry entry for an installed compressor or
decompressor by using the ICRemove function. This function removes the registry
entry of a compressor or decompressor that is not currently loaded in memory.
An
application can restrict the use of a compressor or decompressor by installing,
opening, closing, and removing it.
Alternatively,
to use a function internally as a compressor or decompressor without installing
it in the registry, an application can use the ICOpenFunction function. This function
requires the calling application to have the address of the function to be used
as a compressor or decompressor. When the application finishes using the
function, it must close it by using ICClose. Because the function was
not installed, the application does not need to remove the function from the
registry.
The internal
structure of a function used as a compressor or decompressor should be the same
as the DriverProc
entry-point function used by installable drivers. For more information about
the DriverProc entry-point function, see Installable Drivers.
Note An application
installing a function as a compressor or decompressor must remove the function
before the application is closed so other applications do not try to use the
function. When removing a function, the application must identify it with the
four-character code used to install it.