70 lines
2.2 KiB
Rust
70 lines
2.2 KiB
Rust
use crate::encoder::compression::*;
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use flate2::{write::ZlibEncoder, Compression as FlateCompression};
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/// The Deflate algorithm used to compress image data in TIFF files.
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#[derive(Debug, Clone, Copy)]
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pub struct Deflate {
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level: FlateCompression,
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}
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impl Deflate {
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/// Create a new deflate compressor with a specific level of compression.
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///
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/// The valid levels are 1 through 9 inclusive. The default level is 6.
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///
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/// - `1` stands for light but fast compression
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/// - `6` is the recommended balanced default
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/// - `9` is maximum compression ratio at the cost of slow encoding
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pub fn with_level(level: u8) -> Self {
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Self {
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level: FlateCompression::new(level as u32),
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}
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}
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}
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impl Default for Deflate {
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fn default() -> Self {
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Self::with_level(6)
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}
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}
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impl Compression for Deflate {
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const COMPRESSION_METHOD: CompressionMethod = CompressionMethod::Deflate;
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fn get_algorithm(&self) -> Compressor {
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Compressor::Deflate(*self)
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}
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}
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impl CompressionAlgorithm for Deflate {
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fn write_to<W: Write>(&mut self, writer: &mut W, bytes: &[u8]) -> Result<u64, io::Error> {
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let mut encoder = ZlibEncoder::new(writer, self.level);
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encoder.write_all(bytes)?;
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encoder.try_finish()?;
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Ok(encoder.total_out())
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use crate::encoder::compression::tests::TEST_DATA;
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use std::io::Cursor;
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#[test]
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fn test_deflate() {
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const EXPECTED_COMPRESSED_DATA: [u8; 64] = [
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0x78, 0x9C, 0x15, 0xC7, 0xD1, 0x0D, 0x80, 0x20, 0x0C, 0x04, 0xD0, 0x55, 0x6E, 0x02,
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0xA7, 0x71, 0x81, 0xA6, 0x41, 0xDA, 0x28, 0xD4, 0xF4, 0xD0, 0xF9, 0x81, 0xE4, 0xFD,
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0xBC, 0xD3, 0x9C, 0x58, 0x04, 0x1C, 0xE9, 0xBD, 0xE2, 0x8A, 0x84, 0x5A, 0xD1, 0x7B,
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0xE7, 0x97, 0xF4, 0xF8, 0x08, 0x8D, 0xF6, 0x66, 0x21, 0x3D, 0x3A, 0xE4, 0xA9, 0x91,
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0x3E, 0xAC, 0xF1, 0x98, 0xB9, 0x70, 0x17, 0x13,
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];
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let mut compressed_data = Vec::<u8>::new();
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let mut writer = Cursor::new(&mut compressed_data);
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Deflate::default().write_to(&mut writer, TEST_DATA).unwrap();
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assert_eq!(EXPECTED_COMPRESSED_DATA, compressed_data.as_slice());
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}
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}
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