hitform.pas

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unit HitForm;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  Buttons;

type
  TForm2 = class(TForm)
    procedure FormResize(Sender: TObject);
    procedure FormPaint(Sender: TObject);
  private
    MoveRect, TransRect: TRect;
  public
    procedure WmNcHitTest (var Msg: TWmNcHitTest);
      message wm_NcHitTest;
  end;

var
  Form2: TForm2;

implementation

{$R *.DFM}

procedure TForm2.WmNcHitTest(var Msg: TWmNcHitTest);
var
  Pt: TPoint;
begin
  Pt := Point (Msg.XPos, Msg.YPos);
  Pt := ScreenToClient (Pt);
  if PtInRect (MoveRect, pt) then
    Msg.Result := htCaption
  else if PtInRect (TransRect, pt) then
    Msg.Result := htTransparent
  else
    inherited;
end;

procedure TForm2.FormResize(Sender: TObject);
begin
  MoveRect := Rect (20, 20,
    ClientWidth - 20, ClientHeight div 2 - 10);
  TransRect := Rect (20, ClientHeight div 2 + 10,
    ClientWidth - 20, ClientHeight - 20);
  Invalidate;
end;

procedure TForm2.FormPaint(Sender: TObject);
begin
  // draw the rectangles
  Canvas.Brush.Color:= Font.Color;
  Canvas.FrameRect (MoveRect);
  Canvas.FrameRect (TransRect);
  // draw the text
  Canvas.Brush.Color:= Color;
  DrawText (Canvas.Handle, 'Move', 4, MoveRect,
    dt_Center or dt_VCenter or dt_SingleLine);
  DrawText (Canvas.Handle, 'Transparent', 11, TransRect,
    dt_Center or dt_VCenter or dt_SingleLine);
end;

end.