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;