Dialog Based Initialization (Delphi 4.0)

The Color Conversion C API provides a color space dialog that can be used to initialize a conversion. To do a dialog based initialization follow the steps below:

1.	At the beginning of the Unit1 file, add LTDLLUNT, LTDLLTYP, and LTDLLDEF to the uses section.
2.	Use the following code to implement using the color space dialog for initializing:

function TForm1.ColorDlg_RGBToLAB({in}pSrcRGB, {out}pDstLAB: Pointer; {in}nWidth, {out}nHeight: Integer) : {ret}Integer; 
var 
ClrHandle : THandle; (* color handle *) 
ret: Integer; (* return value *) 
begin 
(* 
****************************************************************** 
* Simple conversion from RGB to CIELab using the LEAD color dialog * 
* Parameters : * 
* pSrcRGB : 24 bit RGB data, this is the input image data * 
* pDstLAB : 24 bit CIELab data, this is the output image data * 
* nWidth : Width of the image * 
* nHeight : Height of the image * 
* Returns SUCCESS when successful or an error code otherwise * 
****************************************************************** 
*) 
(* 
* when the dialog appears choose RGB to LAB conversion from 
* the Miscellaneous options 
*) 
ret := L_ClrDlg(DLG_LAB, (* CIELAb color dialog *) 
Handle, (* Handle to parent window *) 
@ClrHandle, (* I need a color handle *) 
nil (* no need for a CONVERSION_PARAMS data *) 
); 
(* do we have a valid handle *) 
if ret <> SUCCESS then 
   Result := ret 
else 
   begin 
(* do the conversion from RGB to CIELab *) 
ret := L_ClrConvert (ClrHandle, 
pSrcRGB, 
pDstLAB, 
nWidth, 
nHeight, 
0, 
0); 
if ret <> SUCCESS then 
   begin 
(* free before leaving *) 
L_ClrFree (ClrHandle); 
Result := ret; 
end 
else 
   begin 
(* do not forget to free every thing *) 
ret := L_ClrFree (ClrHandle); 
Result := ret; 
end; 
end; 
end;