Loading resources at design time?

Question

Is it possible to load a resource at design time? I am making a speed button component, and I want to automatically load a new image from the resource whenever the button size changes. It already works properly at run time, but at design time, after I set the resource name property, it does not show any icon. I can draw a default rectangle in place of the icon if it is not possible, but it would have been nice to display my icons at design time as well.

function TPngSpeedButton.LoadIcon(ResName: String): Boolean;
var hI: HICON;
    Ico: TIcon;
    ISize: Integer;
    Png: TPngImage;
begin
 Result:= False;
 if ResName = '' then Exit;
 ISize:= Height - 7 - Round(Height * 0.15);
 Png:= TPngImage.Create; Ico:= TIcon.Create;
 try
  if LoadIconWithScaleDown(HInstance, PChar(ResName), ISize, ISize, hI) = S_OK then begin
   Ico.Handle:= hI;
   ConvertToPng(Ico, Png);
   SetPngImage(Png);
   Result:= True;
  end;
 finally
  Png.Free; Ico.Free;
 end;
end;

Answer 1

You can not load icons at design-time from your application resource, since at that time the application executable doesn't even exist as you haven't compiled it yet.

Now, what you might be able to do is create a resource-based dynamic link library (resource DLL) which you compile separately. This way, you would be able to access the DLL resources even at design-time, similar to how the Delphi IDE is already accessing some system resources.

If you don't want to deal with additional DLLs, then put your icons into one or more ImageLists, since images from ImageLists are available both at run-time as well at design-time.