FourdgsChunkIndexEntry class

Opcode 0x08. One entry per chunk; together they are the seek index.

Constructors

FourdgsChunkIndexEntry({required double t0, required double t1, required int chunkOffset, required int chunkLength, required int gaussianCount, required List<FourdgsBandRange> bands, bool extended = false, int kind = 0, int deltaMode = 0, int referenceOffset = 0, int keyframeOffset = 0, int depth = 0, int liveCount = 0})
const

Properties

bands → List<FourdgsBandRange>
Each band is its own byte range, so a reader that has decided to evaluate fewer bands never transfers the ones it will not use.
final
chunkLength → int
final
chunkOffset → int
final
deltaMode → int
0 reference-to-keyframe, 1 reference-to-previous. Meaningful only when kind is 1.
final
depth → int
Delta chunks that must be composed to reach this one — the exact read cost, known from the index before anything is fetched.
final
extended → bool
True when this entry carries the keyframe-delta block below. False for every gaussian-birth file, whose entries stay byte-identical: the block is appended after the band array, so an entry with at least indexDeltaBlockBytes left after the bands carries it and one without simply does not.
final
gaussianCount → int
final
hashCode → int
The hash code for this object.
no setterinherited
keyframeOffset → int
The keyframe at the head of this group. Equals chunkOffset for a keyframe.
final
kind → int
0 keyframe (a Chunk record), 1 delta (a Delta Chunk record).
final
liveCount → int
Gaussians live over [t0, t1) after composition. gaussianCount cannot answer this for a delta entry — there it is the size of the delta, not of the population.
final
referenceOffset → int
The chunk this delta applies to. Strictly less than chunkOffset: references point backwards only, so the chain walk terminates, cycles are unrepresentable, and any complete prefix of a truncated file is a complete set of chains.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
t0 → double
final
t1 → double
final

Methods

covers(double t) → bool
The normative seek rule, per entry.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
overlaps(double a, double b) → bool
True when this chunk can hold a gaussian visible anywhere in [a, b).
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited

Static Methods

parse(Uint8List content, {int fileOffset = 0}) → FourdgsChunkIndexEntry
fileOffset is where content begins in the file, so that a refusal can name a byte someone can seek to. Defaulted rather than required because a caller holding a bare record — a test, a fuzzer — has no file to be relative to, and 0 is then the truth rather than a placeholder.