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exr 0.7.3

Read and write OpenEXR files without any unsafe code
Documentation 
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// see https://github.com/openexr/openexr/blob/master/OpenEXR/IlmImf/ImfCompressor.cpp


//! compresses 16 scan lines at once or
//! compresses 1 single scan line at once

use super::*;
use super::optimize_bytes::*;

use std::io::{self, Read};
use libflate::zlib::{Encoder, Decoder};
use crate::error::Result;

// scanline decompression routine, see https://github.com/openexr/openexr/blob/master/OpenEXR/IlmImf/ImfScanLineInputFile.cpp
// 1. Uncompress the data, if necessary (If the line is uncompressed, it's in XDR format, regardless of the compressor's output format.)
// 3. Convert one scan line's worth of pixel data back from the machine-independent representation
// 4. Fill the frame buffer with pixel data, respective to sampling and whatnot


pub fn decompress_bytes(data: Bytes<'_>, expected_byte_size: usize) -> Result<ByteVec> {
    let mut decompressed = Vec::with_capacity(expected_byte_size);

    {
        let mut decompressor = Decoder::new(data)?;
        decompressor.read_to_end(&mut decompressed)?;
    };

    differences_to_samples(&mut decompressed);
    interleave_byte_blocks(&mut decompressed);
    Ok(decompressed)
}

pub fn compress_bytes(packed: Bytes<'_>) -> Result<ByteVec> {
    let mut packed = Vec::from(packed); // TODO no alloc
    separate_bytes_fragments(&mut packed);
    samples_to_differences(&mut packed);

    {
        let mut compressor = Encoder::new(Vec::with_capacity(packed.len()))?;
        io::copy(&mut packed.as_slice(), &mut compressor)?;
        Ok(compressor.finish().into_result()?)
    }
}