Crate j2k_metal 

Apple Metal GPU adapters for Rust JPEG 2000 / HTJ2K decode and encode paths.

This crate wraps the CPU/native J2K implementation with optional Metal-resident decode surfaces, batch decode sessions, and lossless encode helpers on macOS. Non-macOS builds keep the same API surface and return Error::MetalUnavailable for explicit Metal-only requests.

Structs

Codec

J2K codec marker used by J2K’s generic decode traits.

J2kContext

Reusable JPEG 2000 decode context and cache state.

J2kDecoder

JPEG 2000 decoder that can return host or Metal-resident surfaces.

J2kScratchPool

Caller-owned reusable scratch for j2k.

MetalBackendSession

Placeholder Metal session for non-macOS builds.

MetalEncodeStageAccelerator

Encode-stage accelerator for JPEG 2000 Metal work.

MetalEncodedJ2k

Placeholder Metal codestream type for non-macOS builds.

MetalLosslessBufferEncodeBatchOutcome

Resident Metal lossless J2K/HTJ2K tile batch output and batch-level metrics.

MetalLosslessBufferEncodeOutcome

Metal lossless encode report for buffer-backed codestream output.

MetalLosslessEncodeBatchRequest

Batched lossless encode request over Metal-resident tiles.

MetalLosslessEncodeBatchStats

Resolved resident Metal lossless J2K/HTJ2K tile batch encode metrics.

MetalLosslessEncodeConfig

Tuning knobs for resident Metal lossless J2K/HTJ2K tile batch encode.

MetalLosslessEncodeOutcome

Lossless Metal encode output with host codestream bytes and timings.

MetalLosslessEncodeResidency

Residency decisions used by a lossless Metal encode.

MetalLosslessEncodeStageStats

Optional resident Metal encode stage timings.

MetalLosslessEncodeTile

Placeholder lossless encode tile type for non-macOS builds.

MetalSession

Shared batching session used by J2K Metal submit APIs.

MetalTileBatch

Convenience wrapper for submitting a group of J2K/HTJ2K tiles to one decoder session.

SubmittedJ2kLosslessMetalBufferEncodeBatch

Placeholder submitted Metal-buffer encode for non-macOS builds.

SubmittedJ2kLosslessMetalEncodeBatch

Placeholder submitted multi-tile encode for non-macOS builds.

Surface

Decoded J2K image surface returned by the Metal backend.

Enums

Error

Errors returned by the Metal J2K backend.

MetalEncodeInputStaging

How tile samples reach the encoder’s padded staging layout.

SurfaceResidency

Where a decoded J2K surface is currently resident.

Functions

encode_lossless_batch_with_report

Return Error::MetalUnavailable for reported batch encode on non-macOS.

submit_lossless_batch

Return Error::MetalUnavailable for submitted host-byte batch encode on non-macOS.

submit_lossless_batch_to_metal

Return Error::MetalUnavailable for submitted Metal-buffer batch encode on non-macOS.

validate_lossless_roundtrip_on_metal

Return Error::MetalUnavailable for Metal roundtrip validation on non-macOS.

validate_lossless_roundtrip_on_metal_with_session

Return Error::MetalUnavailable for session validation on non-macOS.