The Write method causes the data in the supplied buffer to be written the output stream. Buffer contains the raw (uncompressed) data to be written, and Count contains the number of bytes to write. 

The TZCompressionStream object caches data internally; data is flushed to the output stream when the cache becomes full, and when the object is destroyed (if pending data remains in the cache). 

After data is written to the output stream, the OnProgress event is called. This gives you an opportunity to update a user interface control such as a progress indicator.  

The result of the Write method is the number of bytes transferred from the buffer 

Read 

Seek 

Write