`pdfAddOCGToAppEvent`

Subscribe an OCG to one or more application events

BOOL32 __stdcall pdfAddOCGToAppEvent(PPDF IPDF, uint32_t Handle, TOCAppEvent Events, TOCGUsageCategory Categories);

Delphi

function pdfAddOCGToAppEvent(const IPDF: PPDF; Handle: Cardinal; Events: TOCAppEvent; Categories: TOCGUsageCategory): LongBool; stdcall;

Purpose. Subscribe an OCG to one or more application events (view/print/export) — the registration step that pdfApplyAppEvent (Form Actions, JavaScript, Application Events, and Layer Object Association) later consults to decide which OCGs' visibility to update when a given event is simulated.

Description. Sets bits in the OCG's FOCGAppEvent bitmask (OR'd with Events) — this is the companion "add" call to the document-level pdfClearOCGAppEvent-style removal function (not itself part of this volume). Categories presumably selects which /Usage sub-dictionary categories (e.g. /View, /Print, /Export) the subscription targets, mirroring the standard PDF optional-content usage-application dictionary structure — this chapter did not trace Categories' exact per-bit effect beyond its being stored alongside Events.

Parameters.

Parameter	Description
`IPDF`	Document handle.
`Handle`	Target OCG handle.
`Events`	Bitmask of application events (view/print/export) to subscribe to.
`Categories`	Which `/Usage` category dictionaries the subscription covers.

Return value. True on success.

C# (P/Invoke)

wrappers/dotnet/LumasPdf.cs

[return: MarshalAs(UnmanagedType.Bool)]

Area

PDF/A & Conformance