Knowing Onclick Event fired - delphi

Question

I use a server client component, and when a file is being received in the TransferFile event of this component, I use an alert message component. So I want, if the user clicks on the alert message, the program to continue executing code in the TransferFile event to accept the file transfer in case the button is clicked, or to exit the procedure when not.
pls see bellow code:
procedure TfrmReadFile.ServerReceiveEvent(Sender: TObject;
Client: TSimpleTCPClient; Event: TTOOCSEvent);
begin
if (Event is TTOOCSEventFileTransfert) then
begin
Alert.Show;
if Alert.OnAlertClick then
begin
with (Event as TTOOCSEventFileTransfert) do
if (dlgSaveFile.Execute) then
with TMemoryStream.Create do
try
Write(Content[1], Length(Content));
SaveToFile(dlgSaveFile.FileName);
finally
Free;
end;
end;
end;
end;
but "if Alert.OnAlertClick then" is wrong
procedure TfrmReadFile.AlertAlertClick(Sender: TObject);
begin
end;
Please help me for these codes.
the AlertMessage is one of the TMS component and it hasn't ShowModal but it has Alert.Show Procedure that I use. and I want to pause the executing code untill the alert show time is finish and if user not click on alert executing the code aborted and no file saved.

Answer 1

From your code it's obvious that by the time you get to show the Alert, the file transfer already occurred: it's only a matter of "Do I save to file" or "Do I discard the content I already received". I'm inferring this information from your use of the TMemoryStream.Write() - that function takes a buffer as a parameter, so I assume the Content[1] gives your the buffer. This also means the Content is allready populated with the data you need. Too late to NOT transfer it, it's already in memory, all you can do is save it to disk or discard it.
I also have no idea how TMS's Alert works, but I'm going to assume only one Alert can be shown at any given time, and I'm going to assume you dropped your Alert on a component (ie: There's only one Alert in the whole program).
You should first alter the code for your "received event" to immediately move the content to a TMemoryStream. Also make sure you don't get into trouble with recursive re-entrance. Add a private field to your form, call it FLastContentReceived: TMemoryStream; Now alter your code to look like this:
procedure TfrmReadFile.ServerReceiveEvent(Sender: TObject;
Client: TSimpleTCPClient; Event: TTOOCSEvent);
begin
if (Event is TTOOCSEventFileTransfert) then
begin
// Re-entry before we managed to handle the previous received file?
if Assigned(FLastContentReceived) then
raise Exception.Create('Recursive re-entry not supported.');
// No re-entry, let's save the content we received so we can save it to file
// if the user clicks the Alert button.
FLastContentReceived := TMemoryStream.Create;
// I don't know what Content is, but you've got that in your code so I
// assume this will work:
FLastContentReceived.Write(Content[1], Length(Content);
// Show the alert; If the OnAlertClick event fires we'll have the received file content
// in the FLastContentRecevied and we'll use that to save the file.
Alert.Show;
end;
end;
You're trying to do an if on Alert.OnAlertClick - so I assume there's an event in your Alert component that's called OnAlertClick. Write this in it's event handler:
procedure TfrmReadFile.AlertAlertClick(Sender: TObject);
begin
if not Assigned(FLastContentReceived) then raise Exception.Create('Bug');
try
if dlgSaveFile.Execute then
FLastContentReceived.SaveToFile(dlgSaveFile.FileName);
finally FreeAndNil(FLastContentReceived);
end;
end;
You'd also need a way to discard the FLastContentReceived if the form is closed before the Alert button gets clicked OR there's a time-out (the Alert goes away without the user clicking it). The first job (getting rid of FLastContentReceived) when the form is closed is simle: add this to your form's OnDestroy:
FLastContentRecevid;Free;
Handling the timeout might a bit more difficult. If the Alert has an event that's called when the alert times out and the Balloon goes away without being clicked then use that event handler to do this:
FreeAndNil(FLastContentRecevid);
If it offers no such thing you could set up a TTimer for an interval equal to the timeout of the alert (or slightly longer to be safe), enable it before showing the alert and do this from it's OnTimer:
procedure TFrmReadFile.Timer1Timer(Sender: TObject);
begin
Timer1.Enabled := False;
FreeAndNil(FLastContentRecevid);
end;