Merlin’s Delphi Forge

Sometimes you want to create a fancy looking form from a bitmap, like WinAMP or K-J?fol. This part isn’t too hard. All you have to do is make a cool graphic, use the TImage component and set the form’s border style to bsNone. Well, all’s good until we want to move the form… Since there is no title bar there may be a problem with this:) Well, as you should already know Delphi can get over any problem. All we have to do is manually take care of the WM_NCHITTEST Windows message.

In this example a TImage component named imgTitle will act like the form’s title bar.

uses
  Messages;
...
  public
    procedure WMNCHitTest(var Message: TWMNCHitTest); message WM_NCHITTEST;
  end;
...
procedure TForm1.WMNCHitTest(var Message: TWMNCHitTest);
var
  P: TPoint;
begin
  inherited;
  P := ScreenToClient(SmallPointToPoint(Message.Pos));
  with imgTitle do
    if (P.X >= Left) and (P.X < Left + Width) and (P.Y >= Top) and (P.Y < Top + Height) then
      Message.Result := htCaption;
end;

Tags: api, behave, bitmap, border style, caption, code, Delphi, form, lt, manually, move, open source, position, screen, source, source code, tip, title bar, trick, winamp, window, windows, wm