unit Unit2;

interface

uses
dbgmsgs,
  Winapi.Windows, SyncObjs,
  System.Classes, Vcl.Graphics;

type
  TImageRenderer = class(TThread)
  private
    fBmp: TBitmap;
    fOnPaint: TNotifyEvent;
    procedure PaintBmp;
  protected
    procedure Execute; override;
  public
    constructor Create;
    destructor Destroy; override;
    property OnPaint: TNotifyEvent read fOnPaint write fOnPaint;
  end;

implementation

uses
  Unit1;

{ ImageRenderer }

constructor TImageRenderer.Create;
begin
  inherited Create;
  fBmp := TBitmap.Create;
  fBmp.SetSize(100, 100);
  fBmp.PixelFormat := pf24Bit;
end;

destructor TImageRenderer.Destroy;
begin
  fBmp.Free;
  inherited;
end;

procedure TImageRenderer.Execute;
var
  ix: Integer;
  iy: Integer;
begin
  while Not Terminated do
  begin
    fBmp.Canvas.Lock;
    for ix := 0 to 99 do
    begin
      for iy := 0 to 99 do
      begin
        fBmp.Canvas.Pixels[ix,iy] := RGB(Random(256),Random(256),Random(256));
      end;
      Sleep(5);
    end;
    fBmp.Canvas.UnLock;
    Synchronize(PaintBmp);
  end;
end;


procedure TImageRenderer.PaintBmp;
begin
  if assigned(fOnPaint) then
  begin
    fOnPaint(fBmp);
  end;
end;



end.


// Formularseite
unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Unit2, Vcl.StdCtrls, Vcl.ExtCtrls;

type
  TForm1 = class(TForm)
    Image1: TImage;
    Button1: TButton;
    Label1: TLabel;
    ICntLbl: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    fRT: TImageRenderer;
    procedure IRTerminate(Sender: TObject);
    procedure IRPaint(Sender: TObject);
  public
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
  if Not Assigned(fRT) then
  begin
    Image1.Picture.Bitmap.SetSize(200,200);
    Image1.Picture.Bitmap.Canvas.Brush.Color := RGB(Random(256),Random(256),Random(256));
    Image1.Picture.Bitmap.Canvas.FillRect(Rect(0,0,200,200));

    fRT := TImageRenderer.Create;
    fRT.OnTerminate := IRTerminate;
    fRT.FreeOnTerminate := TRUE;
    fRT.OnPaint := IRPaint;
    Button1.Caption := 'Stop';
  end
  else
  begin
    fRT.Terminate;
    Button1.Caption := 'Go';
  end;
end;

procedure TForm1.IRTerminate(Sender: TObject);
begin
  fRT := NIL;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  if Assigned(fRT) then
    fRT.Terminate;
end;

procedure TForm1.IRPaint(Sender: TObject);
Var
  iBmp: TBitmap;
begin
  iBmp := Sender As TBitmap;
  Image1.Picture.Bitmap.Canvas.Draw(10,10, iBmp);
  //--------------------------------------------
  ICntLbl.Tag := ICntLbl.Tag + 1;
  ICntLbl.Caption := IntToStr(ICntLbl.Tag);
end;

end.