{
* UDownloadMonitor.pas
*
* Manages download progress reporting for web service object.
*
* $Rev$
* $Date$
*
* ***** BEGIN LICENSE BLOCK *****
*
* Version: MPL 1.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
* the specific language governing rights and limitations under the License.
*
* The Original Code is UDownloadMonitor.pas
*
* The Initial Developer of the Original Code is Peter Johnson
* (http://www.delphidabbler.com/).
*
* Portions created by the Initial Developer are Copyright (C) 2006-2009 Peter
* Johnson. All Rights Reserved.
*
* Contributor(s)
* NONE
*
* ***** END LICENSE BLOCK *****
}
unit UDownloadMonitor;
interface
uses
// Indy
IdHTTP, IdComponent, IdGlobal;
// TWorkEvent and TWorkBeginEvent have different signatures between Indy v10.1.x
// and v10.2.x and later. The following is an attempt to decide which signature
// to use. Should this unit fail to compile, you can define INDY_WORKEVENT_INT64
// in the project options or on the compiler command line to override this
// code. Define INDY_WORKEVENT_INT64 to use a Int64 parameter and or define
// INDY_WORKEVENT_INT32 to use a 32 bit integer as the last paramter of both
// event handler types.
{$IF not Defined(INDY_WORKEVENT_INT64) and not Defined(INDY_WORKEVENT_INT64)}
{$IF gsIdVersion >= '10.2'}
{$DEFINE INDY_WORKEVENT_INT64}
{$UNDEF INDY_WORKEVENT_INT32}
{$ELSE}
{$UNDEF INDY_WORKEVENT_INT64}
{$DEFINE INDY_WORKEVENT_INT32}
{$IFEND}
{$IFEND}
{$IF Defined(INDY_WORKEVENT_INT32) and Defined(INDY_WORKEVENT_INT64)}
{$MESSAGE FATAL
'Can''t define both INDY_WORKEVENT_INT32 and INDY_WORKEVENT_INT32'}
{$IFEND}
type
{
TDownloadMonitorCallback:
Type of callback method called by TDownloadMonitor when download information
changes.
}
TDownloadMonitorCallback = procedure of object;
{
TDownloadMonitor:
Manages download progress reporting for web service object.
}
TDownloadMonitor = class(TObject)
private
fCallback: TDownloadMonitorCallback;
{Reference to method called to notify changes in download state}
fBytesExpected: Integer;
{Number of bytes expected in current download}
fBytesReceived: Integer;
{Number of bytes received to date in curent download}
procedure HTTPWorkHandler(Sender: TObject; AWorkMode: TWorkMode;
AWorkCount:
{$IFDEF INDY_WORKEVENT_INT64}Int64{$ENDIF}
{$IFDEF INDY_WORKEVENT_INT32}Integer{$ENDIF});
{Handles Indy HTTP client's OnWork event. We process only download events.
Upload events are ignored. Updates record of bytes received.
@param Sender [in] Not used.
@param AWorkMode [in] Whether download (read) or upload (write) event.
@param AWorkCount [in] Number of bytes received to date.
}
procedure HTTPWorkBeginHandler(Sender: TObject; AWorkMode: TWorkMode;
AWorkCountMax:
{$IFDEF INDY_WORKEVENT_INT64}Int64{$ENDIF}
{$IFDEF INDY_WORKEVENT_INT32}Integer{$ENDIF});
{Handles Indy HTTP client's OnWorkBegin event. We process only download
events. Upload events are ignored. Records number of expected bytes in
download.
@param Sender [in] Not used.
@param AWorkMode [in] Whether download (read) or upload (write) event.
@param AWorkCountMax [in] Number of bytes expected in download.
}
procedure HTTPWorkEndHandler(Sender: TObject; AWorkMode: TWorkMode);
{Handles Indy HTTP client's OnWorkEnd event. We process only download
events. Upload events are ignored. Finalises download.
@param Sender [in] Not used.
@param AWorkMode [in] Whether download (read) or upload (write) event.
}
procedure NotifyChange;
{Notifies change in download state by calling callback method.
}
procedure Init(const BytesExpected: Integer);
{Initialises new download.
@param BytesExpected [in] Number of bytes to be downloaded.
}
procedure Update(const BytesReceived: Integer);
{Updates download statistics.
@param BytesReceived [in] Number of bytes received to date.
}
procedure Done;
{Finalises a download. Adjusts bytes received and calls callback.
}
public
constructor Create(const HTTP: TIdHTTP;
const Callback: TDownloadMonitorCallback);
{Class constructor. Sets up object to monitor downloads received by Indy
HTTP components.
@param HTTP [in] Reference to Indy HTTP component we use to intercept
download events. Must not be nil.
@param Callback [in] Method to call to notify of download updates. Must
not be nil.
}
property BytesReceived: Integer
read fBytesReceived;
{Total number of bytes received in current download}
property BytesExpected: Integer
read fBytesExpected;
{Total number of bytes expected in current download}
end;
implementation
{ TDownloadMonitor }
constructor TDownloadMonitor.Create(const HTTP: TIdHTTP;
const Callback: TDownloadMonitorCallback);
{Class constructor. Sets up object to monitor downloads received by Indy HTTP
components.
@param HTTP [in] Reference to Indy HTTP component we use to intercept
download events. Must not be nil.
@param Callback [in] Method to call to notify of download updates. Must not
be nil.
}
begin
Assert(Assigned(HTTP), ClassName + '.Create: HTTP is nil');
Assert(Assigned(Callback), ClassName + '.Create: Callback is nil');
inherited Create;
HTTP.OnWork := HTTPWorkHandler;
HTTP.OnWorkBegin := HTTPWorkBeginHandler;
HTTP.OnWorkEnd := HTTPWorkEndHandler;
fCallback := Callback;
end;
procedure TDownloadMonitor.Done;
{Finalises a download. Adjusts bytes received and calls callback.
}
begin
fBytesReceived := fBytesExpected;
NotifyChange;
end;
procedure TDownloadMonitor.HTTPWorkBeginHandler(Sender: TObject;
AWorkMode: TWorkMode;
AWorkCountMax:
{$IFDEF INDY_WORKEVENT_INT64}Int64{$ENDIF}
{$IFDEF INDY_WORKEVENT_INT32}Integer{$ENDIF});
{Handles Indy HTTP client's OnWorkBegin event. We process only download
events. Upload events are ignored. Records number of expected bytes in
download.
@param Sender [in] Not used.
@param AWorkMode [in] Whether download (read) or upload (write) event.
@param AWorkCountMax [in] Number of bytes expected in download.
}
begin
if AWorkMode = wmRead then
Init(AWorkCountMax)
end;
procedure TDownloadMonitor.HTTPWorkEndHandler(Sender: TObject;
AWorkMode: TWorkMode);
{Handles Indy HTTP client's OnWorkEnd event. We process only download events.
Upload events are ignored. Finalises download.
@param Sender [in] Not used.
@param AWorkMode [in] Whether download (read) or upload (write) event.
}
begin
if AWorkMode = wmRead then
Done;
end;
procedure TDownloadMonitor.HTTPWorkHandler(Sender: TObject;
AWorkMode: TWorkMode;
AWorkCount:
{$IFDEF INDY_WORKEVENT_INT64}Int64{$ENDIF}
{$IFDEF INDY_WORKEVENT_INT32}Integer{$ENDIF});
{Handles Indy HTTP client's OnWork event. We process only download events.
Upload events are ignored. Updates record of bytes received.
@param Sender [in] Not used.
@param AWorkMode [in] Whether download (read) or upload (write) event.
@param AWorkCount [in] Number of bytes received to date.
}
begin
if AWorkMode = wmRead then
Update(AWorkCount);
end;
procedure TDownloadMonitor.Init(const BytesExpected: Integer);
{Initialises new download.
@param BytesExpected [in] Number of bytes to be downloaded.
}
begin
fBytesExpected := BytesExpected;
fBytesReceived := 0;
NotifyChange;
end;
procedure TDownloadMonitor.NotifyChange;
{Notifies change in download state by calling callback method.
}
begin
fCallback;
end;
procedure TDownloadMonitor.Update(const BytesReceived: Integer);
{Updates download statistics.
@param BytesReceived [in] Number of bytes received to date.
}
begin
fBytesReceived := BytesReceived;
NotifyChange;
end;
end.
