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Delphi - stream synchronization with the frame

Good afternoon :-), I have one shot. This frame I am dynamically created by the main form.

Basic form:

Interface := TInterface.Create(self); with handlingInterface do begin Parent := Form1; Left := 0; Top := 35; Width := 570; Height := 250; end;

In the frame, I have Thread. I call this stream from the frame. Why can I synchronize Thread with the frame? There is no one:

 var Form1: TForm1;

I call Thread inside the frame , and I want to change the position of the ProgressBar in the frame . I do not know why I can access the ProgressBar in the Synchronize Thread method.

If a form were included in Thread and ProgressBar - Synchronize Access - Form1.ProgressBar ...

But I have Thread and ProgressBar in Frame .

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2 answers

You can give a link to your progress bar in a stream.

Stream class example.

 unit Unit6; interface uses Classes, ComCtrls; type TProgressBarThread = class(TThread) private { Private declarations } FProgressBar: TProgressBar; procedure MoveProgress; protected procedure Execute; override; public procedure SetProgressBar(ProgressBar: TProgressBar); end; implementation { ProgressBarThread } procedure TProgressBarThread.Execute; begin { Place thread code here } Synchronize(MoveProgress); end; procedure TProgressBarThread.MoveProgress; begin FProgressBar.StepIt; end; procedure TProgressBarThread.SetProgressBar(ProgressBar: TProgressBar); begin FProgressBar := ProgressBar; end; end.

Use it as

 var PBT: TProgressBarThread; begin PBT := TProgressBarThread.Create(True); PBT.FreeOnTerminate := True; PBT.SetProgressBar(ProgressBar1); PBT.Start; // PBT.Resume; end;
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If the only thing you are trying to do is update the progress bar from the stream, there is a lower weight option. Instead, I would rather use PostMessage. You do not want your thread to know too much about the details of the frame.

When you create a stream, give it a handle to your frame so that it knows where to send the message. Ask the frame to listen to the Windows message, which includes the progress position, and update the progress bar.

Here is a very simple example that increases the execution step from 0 to 100 with a short sleep between each increment:

 unit Unit2; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls, ComCtrls; const WM_PROGRESS_MESSAGE = WM_USER + 99; type TProgressThread = class(TThread) private FWindowHandle: HWND; protected procedure Execute; override; public property WindowHandle: HWND read FWindowHandle write FWindowHandle; end; TFrame2 = class(TFrame) ProgressBar1: TProgressBar; Button1: TButton; procedure Button1Click(Sender: TObject); private procedure OnProgressMessage(var Msg: TMessage); message WM_PROGRESS_MESSAGE; public end; implementation {$R *.dfm} { TFrame2 } procedure TFrame2.Button1Click(Sender: TObject); var lThread: TProgressThread; begin lThread := TProgressThread.Create(True); lThread.FreeOnTerminate := True; lThread.WindowHandle := Self.Handle; lThread.Start; end; procedure TFrame2.OnProgressMessage(var Msg: TMessage); begin ProgressBar1.Position := Msg.WParam; end; { TProgressThread } procedure TProgressThread.Execute; var lProgressCount: Integer; begin inherited; for lProgressCount := 0 to 100 do begin PostMessage(FWindowHandle, WM_PROGRESS_MESSAGE, lProgressCount, 0); Sleep(15); end; end; end.
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