SetOptionalContentMembership

Content Streams and Optional Content Groups

Description

Atomically replaces the group list, compatibility policy and optional PDF 1.6 visibility expression of a membership dictionary

Syntax

Function TPDFlib.SetOptionalContentMembership(MembershipID: Integer; Const OptionalContentGroupIDs: Array Of Integer; Policy: TPDFlibOCMDPolicy; Const Expression: Array Of TPDFlibOCMDExpressionItem): Integer;

Parameters

MembershipID	A handle returned by `NewOptionalContentMembership`
OptionalContentGroupIDs	A non-empty group array retained as the compatibility fallback
Policy	The fallback `/P` policy
Expression	A flat prefix expression, or an empty array to remove `/VE`

Return values

0	The membership, groups or expression were invalid and the existing dictionary was not changed
1	The membership was updated

Expression format

The first item must be oekAnd, oekOr or oekNot

oekNot requires one operand, while oekAnd and oekOr require one or more operands

Each operator is followed by exactly OperandCount prefix operands; group items use OperandCount = 0

// And(GroupA, Not(GroupB))
Expression[0].Kind := oekAnd;
Expression[0].OperandCount := 2;
Expression[1].Kind := oekGroup;
Expression[1].OptionalContentGroupID := GroupA;
Expression[2].Kind := oekNot;
Expression[2].OperandCount := 1;
Expression[3].Kind := oekGroup;
Expression[3].OptionalContentGroupID := GroupB;

Remarks

Validation and expression construction are linear in the number of items and nesting is limited to 64 levels

When /VE is present the output version is at least PDF 1.6, while /OCGs and /P remain available to older readers