System.ZLib.TCustomZStream.OnProgress
Delphi
property OnProgress: TNotifyEvent read FOnProgress write FOnProgress;
C++
__property System::Classes::TNotifyEvent OnProgress = {read=FOnProgress, write=FOnProgress};
Properties
| Type | Visibility | Source | Unit | Parent |
|---|---|---|---|---|
| event | protected | System.ZLib.pas System.ZLib.hpp |
System.ZLib | TCustomZStream |
Description
Occurs when reading or writing a large block of data in a single call.
Classes derived from TCustomZStream can use the OnProgress event to perform an action during a long read or write operation.
For example, the TCompressionStream class calls the OnProgress event handler, after the stream's output buffer has been filled and subsequently written. Similarly, the TDecompressionStream class calls the OnProgress event handler when its input buffer has been filled and is ready to be decompressed. You can use the OnProgress event to update a user interface control, such as a progress indicator. You can use the Position property, inherited from TStream, to determine the number of raw (uncompressed) bytes written to the output stream so far.