How do I extract the alternate color values of a separation color?

For Separation colors, the equivalents are retrieved by running the color value through the alternate color function using the PDApplyFunction() API.

float inVal[4], tintTrans[4];
...
/* If this element has a GState, retrieve the Color Information here: */
 if (PDEElementHasGState (pdeElement, &graphicState, (sizeof (PDEGraphicState)) ))
{
 if ( !strcmp ( ASAtomGetString(PDEColorSpaceGetName(graphicState.fillColorSpec.space)), N_SEPARATION) )

         {
         DURING
          /* Get the name of the custom color : */
         strcpy (separationColor, "");
         PDEColorSpaceGetCosObj (graphicState.fillColorSpec.space, &cosObj);
         /* Separation Color Space entry has four entries */
         arrayEntry = CosArrayGet(cosObj,0);
         /* First is the family name */
         printf("\nFamily Name = %s\n",ASAtomGetString( CosNameValue (arrayEntry)) );
         arrayEntry = CosArrayGet(cosObj,1);
         /* Second is the name parameter */
         printf("name parameter = %s\n",ASAtomGetString( CosNameValue (arrayEntry)) );
         arrayEntry = CosArrayGet(cosObj,2);
         /*Third is the alternateSpace (must be array or name object) */
         printf("alternateSpace = %s\n",ASAtomGetString( CosNameValue (arrayEntry)) );
         arrayEntry = CosArrayGet(cosObj,3);
          /*Fourth is the tintTransForm */
         InVal[0] = FixedToFloat(graphicState.fillColorSpec.value.color[0]);
         PDApplyFunction(arrayEntry, InVal, tintTrans);
         printf("TintTrans color0 = %f \n",tintTrans[0]);
         printf("TintTrans color1 = %f \n",tintTrans[1]);
         printf("TintTrans color2 = %f \n",tintTrans[2]);
         printf("TintTrans color3 = %f \n",tintTrans[3]);

         HANDLER
         printf ("Error. Can't retrieve colorObj.\n");
         handleError (ERRORCODE);
         END_HANDLER
         }

//#endif
foundGState = 1;
} /* end hasGState */

For ICC-based colors use the color values returned in an appropriate gray, RGB or CMYK space. ThePDEColorSpaceGetNumComps() API will return the number of color components in the ICC color space:

• DeviceGray, 1
• DeviceRGB, 3
• DeviceCMYK, 4

The PDEColorSpaceGetNumComps() API will always return “1” for Separation color spaces because there is only one component for a Separation color space (by definition).