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evmsg.pas
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evmsg.pas
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unit EvMsg;
{$mode objfpc}{$H+}
interface
uses
Classes, SysUtils;
type
TMessageGenerator = class;
{ IMessageReceiver }
{ Interface for an object, that has to receive messages from a
TMessageGenerator instance }
IMessageReceiver = interface
procedure GenerateEvents; {is called by a TMessageGenerator instance to
send a message to an object with this Interface, calls, for example,
the method DispatchMessage or DispatchMessageStr of that object}
property MessageGenerator: TMessageGenerator;
end;
{ TMessageGenerator }
TMessageGenerator = class(TThread)
private
NewReceiver, DestroyedReceiver: IMessageReceiver;
function GetReceiverList: TList;
private
FReceiverList: TList;
function GetReceiverCount: Integer;
function GetReceivers(I: Integer): IMessageReceiver;
property ReceiverList: TList read GetReceiverList;
protected
procedure Execute; override;
property Receivers[I: Integer]: IMessageReceiver read GetReceivers;
public
function AddReceiver(AReceiver: IMessageReceiver): Boolean;
function RemoveReceiver(AReceiver: IMessageReceiver): Boolean;
destructor Destroy; override;
property ReceiverCount: Integer read GetReceiverCount;
end;
implementation
{ TMessageGenerator }
function TMessageGenerator.GetReceiverList: TList;
begin
if not Assigned(FReceiverList) then FReceiverList := TList.Create;
Result := FReceiverList
end;
function TMessageGenerator.GetReceiverCount: Integer;
begin
if Assigned(FReceiverList) then Result := FReceiverList.Count
else Result := 0
end;
function TMessageGenerator.GetReceivers(I: Integer): IMessageReceiver;
begin
Result := IMessageReceiver(ReceiverList[I])
end;
procedure TMessageGenerator.Execute;
var
I: Integer;
begin
while not Terminated do begin
if Suspended then Continue;
if NewReceiver <> nil then begin
ReceiverList.Add(NewReceiver);
NewReceiver := nil
end;
if DestroyedReceiver <> nil then begin
ReceiverList.Remove(DestroyedReceiver);
DestroyedReceiver := nil;
end;
I := 0;
while I < ReceiverCount do begin
if Suspended then Continue;
if Terminated then Exit;
Synchronize(@Receivers[I].GenerateEvents);
Inc(I)
end;
end;
end;
function TMessageGenerator.AddReceiver(AReceiver: IMessageReceiver): Boolean;
begin
if Suspended then begin
if ReceiverList.IndexOf(AReceiver) = -1 then ReceiverList.Add(AReceiver);
Result := True
end
else
if NewReceiver = nil then begin
NewReceiver := AReceiver;
Result := True
end
else Result := False
end;
function TMessageGenerator.RemoveReceiver(AReceiver: IMessageReceiver): Boolean;
begin
if Suspended then begin
ReceiverList.Remove(AReceiver);
Result := True
end
else
if DestroyedReceiver = nil then begin
DestroyedReceiver := AReceiver;
Result := True
end
else Result := False;
end;
destructor TMessageGenerator.Destroy;
begin
Terminate;
FReceiverList.Free;
inherited Destroy;
end;
end.