function PageUsesOverprint: Boolean;
| Result | Boolean. True when the page turns overprint on for stroking or filling, False when it never does. |
Overprint decides whether an ink prints over what is already there or knocks it out. A page that relies on it looks the same on screen but different on press, so prepress checks call this before deciding whether an overprint preview is needed
The answer covers the whole current page, not one object
Native overprint detection is a capability of the loaded PDFium module; when it is missing the call raises EPdfError instead of returning False, so the two cases stay distinguishable