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Draw on frame

Question:

Is it possible to draw on the frame of a form?

Answer:

Create a message handler for the Windows Message WM_NCPAINT message. The following example paints a 1 pixel red border around the frame of the form.

Example:

type

  TForm1 = class(TForm)

  private

  { Private declarations }

  procedure WMNCPaint(var Msg : TWMNCPaint); message WM_NCPAINT;

  public

  { Public declarations }

  end;

var

  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.WMNCPaint(var Msg: TWMNCPaint);

var

  dc : hDc;

  Pen : hPen;

  OldPen : hPen;

  OldBrush : hBrush;

begin

  inherited;

  dc := GetWindowDC(Handle);

  msg.Result := 1;

  Pen := CreatePen(PS_SOLID, 1, RGB(255, 0, 0));

  OldPen := SelectObject(dc, Pen);

  OldBrush := SelectObject(dc, GetStockObject(NULL_BRUSH));

  Rectangle(dc, 0,0, Form1.Width, Form1.Height);

  SelectObject(dc, OldBrush);

  SelectObject(dc, OldPen);

  DeleteObject(Pen);

  ReleaseDC(Handle, Canvas.Handle);

end;