tiff/encoder/compression/
deflate.rs

1use crate::encoder::compression::*;
2use flate2::{write::ZlibEncoder, Compression as FlateCompression};
3
4/// The Deflate algorithm used to compress image data in TIFF files.
5#[derive(Debug, Clone, Copy)]
6pub struct Deflate {
7    level: FlateCompression,
8}
9
10/// The level of compression used by the Deflate algorithm.
11/// It allows trading compression ratio for compression speed.
12#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
13#[non_exhaustive]
14#[derive(Default)]
15pub enum DeflateLevel {
16    /// The fastest possible compression mode.
17    Fast = 1,
18    /// The conserative choice between speed and ratio.
19    #[default]
20    Balanced = 6,
21    /// The best compression available with Deflate.
22    Best = 9,
23}
24
25impl Deflate {
26    /// Create a new deflate compressor with a specific level of compression.
27    pub fn with_level(level: DeflateLevel) -> Self {
28        Self {
29            level: FlateCompression::new(level as u32),
30        }
31    }
32}
33
34impl Default for Deflate {
35    fn default() -> Self {
36        Self::with_level(DeflateLevel::default())
37    }
38}
39
40impl Compression for Deflate {
41    const COMPRESSION_METHOD: CompressionMethod = CompressionMethod::Deflate;
42
43    fn get_algorithm(&self) -> Compressor {
44        Compressor::Deflate(*self)
45    }
46}
47
48impl CompressionAlgorithm for Deflate {
49    fn write_to<W: Write>(&mut self, writer: &mut W, bytes: &[u8]) -> Result<u64, io::Error> {
50        let mut encoder = ZlibEncoder::new(writer, self.level);
51        encoder.write_all(bytes)?;
52        encoder.try_finish()?;
53        Ok(encoder.total_out())
54    }
55}
56
57#[cfg(test)]
58mod tests {
59    use super::*;
60    use crate::encoder::compression::tests::TEST_DATA;
61    use std::io::Cursor;
62
63    #[test]
64    fn test_deflate() {
65        const EXPECTED_COMPRESSED_DATA: [u8; 64] = [
66            0x78, 0x9C, 0x15, 0xC7, 0xD1, 0x0D, 0x80, 0x20, 0x0C, 0x04, 0xD0, 0x55, 0x6E, 0x02,
67            0xA7, 0x71, 0x81, 0xA6, 0x41, 0xDA, 0x28, 0xD4, 0xF4, 0xD0, 0xF9, 0x81, 0xE4, 0xFD,
68            0xBC, 0xD3, 0x9C, 0x58, 0x04, 0x1C, 0xE9, 0xBD, 0xE2, 0x8A, 0x84, 0x5A, 0xD1, 0x7B,
69            0xE7, 0x97, 0xF4, 0xF8, 0x08, 0x8D, 0xF6, 0x66, 0x21, 0x3D, 0x3A, 0xE4, 0xA9, 0x91,
70            0x3E, 0xAC, 0xF1, 0x98, 0xB9, 0x70, 0x17, 0x13,
71        ];
72
73        let mut compressed_data = Vec::<u8>::new();
74        let mut writer = Cursor::new(&mut compressed_data);
75        Deflate::default().write_to(&mut writer, TEST_DATA).unwrap();
76        assert_eq!(EXPECTED_COMPRESSED_DATA, compressed_data.as_slice());
77    }
78}
tiff/encoder/compression/deflate.rs

tiff/encoder/compression/
deflate.rs
