Just draw a rectangle and a circle, then give them different colors. Choose AI menu "Object | Blend | Make", before this step you could set "Specified steps" to an integer in "Blend Options...", now you get a series of blended arts. Using Direct Select Tool you can select the rectangle or circle you drawed at first.
My question is, how to write code to know if the art object you selected is one part of the blended series? I looked into the document but cannot find a proper API to get the infomation in AIArtSuite. (for CS5 & CS6)
Cound anyone help me, thanks in advance.
I found that by this way,
sArt->GetArtType(artHandle, &artType);
if (artType == kPluginArt) // blend object
...
A blend object's type is recognized as kPluginArt. But I'm not sure if other art will be of this type.