Delphi Tips

SemiTransparent Window

Here is a example how you can make your forms/dialogs make semi transparent, the value of TR_BLEND decides the activety of blending your forms or dialogs.

By value 254  is no blending, by value zero it is almost invisible. 254 should be the maximum value to use and 0 the minimum. It was tested on Windows XP only. It can give great effect on your program when you work with images. Hope its usefull.

{some constants & global variables}
CONST TRBLEND_DEFAULT     = 254;
VAR   TR_BLEND  : INTEGER = TRBLEND_DEFAULT;
      RGB_RED   : INTEGER = 0;
      RGB_GREEN : INTEGER = 0;
      RGB_BLUE  : INTEGER = 0;

{Transparent Code for forms, XP /2000}
const
  BLEND_COLOR     = $00000001;
  BLEND_ALPHA     = $00000002;

{the procedure for blending dialogs/forms}
procedure DMBlend(Handle : THandle; Blend,
                   rgbred,rgbgreen,rgbblue:Integer);
var
   ExtStyle : LongInt;
begin
  ExtStyle := GetWindowLong(Handle, GWL_EXSTYLE);
  SetWindowLong(Handle, GWL_EXSTYLE, ExtStyle or
                                        WS_EX_LAYERED);
  SetLayeredWindowAttributes(Handle,
               RGB(rgbred,rgbgreen,rgbblue),
               TR_BLEND, BLEND_ALPHA or BLEND_COLOR);
end;

{calling the procedure}
DMBlend(form.Handle,TR_BLEND,
                           RGB_RED,RGB_GREEN,RGB_BLUE);

 

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