Struct Codestream

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pub struct Codestream { /* private fields */ }

Expand description

The main codestream interface for encoding and decoding HTJ2K images.

Codestream is the public wrapper over the internal codec engine, mirroring the C++ ojph::codestream class (which uses a pImpl pattern).

§Examples

Lossless encode + decode round-trip (single-component 8-bit)

use openjph_core::codestream::Codestream;
use openjph_core::file::{MemOutfile, MemInfile};
use openjph_core::types::{Point, Size};

// Configure a minimal 8×8 grayscale image
let (w, h) = (8u32, 8u32);
let mut cs = Codestream::new();
cs.access_siz_mut().set_image_extent(Point::new(w, h));
cs.access_siz_mut().set_num_components(1);
cs.access_siz_mut().set_comp_info(0, Point::new(1, 1), 8, false);
cs.access_siz_mut().set_tile_size(Size::new(w, h));
cs.access_cod_mut().set_num_decomposition(0);
cs.access_cod_mut().set_reversible(true);
cs.access_cod_mut().set_color_transform(false);
cs.set_planar(0);

// Encode
let mut out = MemOutfile::new();
cs.write_headers(&mut out, &[]).unwrap();
let row = vec![42i32; w as usize];
for _ in 0..h { cs.exchange(&row, 0).unwrap(); }
cs.flush(&mut out).unwrap();

// Decode
let data = out.get_data().to_vec();
let mut inp = MemInfile::new(&data);
let mut dec = Codestream::new();
dec.read_headers(&mut inp).unwrap();
dec.create(&mut inp).unwrap();
for _ in 0..h {
    let line = dec.pull(0).unwrap();
    assert_eq!(line, row);
}

Implementations§

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impl Codestream

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pub fn new() -> Self

Creates a new codestream with default parameters.

All marker segments (SIZ, COD, QCD, NLT) are initialised to sensible defaults. You must at least set the image extent, number of components, and component info before encoding.

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pub fn restart(&mut self)

Resets the codestream so it can be reused for another encode/decode operation without reallocating.

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pub fn access_siz(&self) -> &ParamSiz

Returns a shared reference to the SIZ (image/tile size) parameters.

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pub fn access_siz_mut(&mut self) -> &mut ParamSiz

Returns a mutable reference to the SIZ parameters for configuration.

Use this before calling write_headers() to set image extent, tile size, number of components, and per-component info.

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pub fn access_cod(&self) -> &ParamCod

Returns a shared reference to the COD (coding style) parameters.

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pub fn access_cod_mut(&mut self) -> &mut ParamCod

Returns a mutable reference to the COD parameters for configuration.

Use this before calling write_headers() to set decomposition levels, reversibility, block sizes, and color transform.

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pub fn access_qcd(&self) -> &ParamQcd

Returns a shared reference to the QCD (quantization) parameters.

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pub fn access_qcd_mut(&mut self) -> &mut ParamQcd

Returns a mutable reference to the QCD parameters for configuration.

For lossy (irreversible) compression, use set_delta() to set the base quantization step size.

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pub fn access_nlt(&self) -> &ParamNlt

Returns a shared reference to the NLT (nonlinearity) parameters.

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pub fn access_nlt_mut(&mut self) -> &mut ParamNlt

Returns a mutable reference to the NLT parameters for configuration.

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pub fn enable_resilience(&mut self)

Enables resilient (error-tolerant) mode for decoding.

When enabled, the decoder attempts to recover from malformed tile-part headers rather than returning an error.

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pub fn set_planar(&mut self, planar: i32)

Sets the line exchange mode.

0 — interleaved (all components for each line exchanged together)
non-zero — planar (one component at a time)

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pub fn set_profile(&mut self, name: &str) -> Result<()>

Sets the codestream profile.

Accepted values: "IMF", "BROADCAST", "CINEMA2K", "CINEMA4K", etc.

§Errors

Returns OjphError::InvalidParam if name is not a recognised profile string.

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pub fn set_tilepart_divisions(&mut self, value: u32)

Sets tilepart division flags (bit-field).

Use 0x1 for resolution-based divisions and 0x2 for component-based divisions.

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pub fn request_tlm_marker(&mut self, needed: bool)

Requests that TLM (tile-part length) markers be written in the codestream header.

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pub fn restrict_input_resolution( &mut self, skipped_res_for_data: u32, skipped_res_for_recon: u32, )

Restricts the number of resolution levels used during decoding.

skipped_res_for_data controls how many resolution levels are skipped when reading tile data. skipped_res_for_recon controls how many are skipped for reconstruction.

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