Add TIFF compression and corresponding tests

README.md

@@ -17,7 +17,7 @@ TIFF decoding and encoding library in pure Rust
 This table lists photometric interpretations and sample formats which are supported for encoding and decoding. The entries are `ColorType` variants for which sample bit depths are supported. Only samples where all bit depths are equal are currently supported. For example, `RGB(8)` means that the bit depth [8, 8, 8] is supported and will be interpreted as an 8 bit per channel RGB color type.
 
 | `PhotometricInterpretation` | UINT Format                             | IEEEFP Format             |
-|-|-|-|
+| --------------------------- | --------------------------------------- | ------------------------- |
 | `WhiteIsZero`               | Gray(8\|16\|32\|64)                     | Gray(32\|64)              |
 | `BlackIsZero`               | Gray(8\|16\|32\|64)                     | Gray(32\|64)              |
 | `RGB`                       | RGB(8\|16\|32\|64), RGBA(8\|16\|32\|64) | RGB(32\|64), RGBA(32\|64) |
@@ -30,10 +30,10 @@ This table lists photometric interpretations and sample formats which are suppor
 ### Compressions
 
 |          | Decoding | Encoding |
-|-|-|-|
+| -------- | -------- | -------- |
 | None     | ✓        | ✓        |
-| LZW | ✓ | |
-| Deflate | ✓ | |
+| LZW      | ✓        | ✓        |
+| Deflate  | ✓        | ✓        |
 | PackBits | ✓        |          |
 
 

benches/lzw.rs

@@ -33,7 +33,7 @@ fn main() {
                 def.data,
                 |b, input| b.iter(|| read_image(input)),
             );
-    };
+    }
 
     let mut c = Criterion::default().configure_from_args();
     let mut group = c.benchmark_group("tiff-lzw");

src/encoder/compression/deflate.rs

@@ -0,0 +1,108 @@
+use std::{
+    convert::TryInto,
+    io::{Seek, Write},
+};
+
+use flate2::{write::ZlibEncoder, Compression as FlateCompression};
+
+use crate::{
+    encoder::{
+        colortype::ColorType, compression::Compression, DirectoryEncoder, TiffKind, TiffValue,
+    },
+    tags::CompressionMethod,
+    TiffResult,
+};
+
+/// The Deflate algorithm used to compress image data in TIFF files.
+#[derive(Debug, Clone)]
+pub struct Deflate {
+    level: FlateCompression,
+    buffer: Vec<u8>,
+}
+
+/// The level of compression used by the Deflate algorithm.
+/// It allows trading compression ratio for compression speed.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+#[non_exhaustive]
+pub enum DeflateLevel {
+    /// The fastest possible compression mode.
+    Fast = 1,
+    /// The conserative choice between speed and ratio.
+    Balanced = 6,
+    /// The best compression available with Deflate.
+    Best = 9,
+}
+
+impl Default for DeflateLevel {
+    fn default() -> Self {
+        DeflateLevel::Balanced
+    }
+}
+
+impl Deflate {
+    /// Lets be greedy and allocate more bytes in advance. We will likely encode longer image strips.
+    const DEFAULT_BUFFER_SIZE: usize = 256;
+
+    /// Create a new deflate compr+essor with a specific level of compression.
+    pub fn with_level(level: DeflateLevel) -> Self {
+        Self {
+            buffer: Vec::with_capacity(Self::DEFAULT_BUFFER_SIZE),
+            level: FlateCompression::new(level as u32),
+        }
+    }
+}
+
+impl Default for Deflate {
+    fn default() -> Self {
+        Self::with_level(DeflateLevel::default())
+    }
+}
+
+impl Compression for Deflate {
+    const COMPRESSION_METHOD: CompressionMethod = CompressionMethod::Deflate;
+
+    fn write_to<'a, T: ColorType, K: TiffKind, W: 'a + Write + Seek>(
+        &mut self,
+        encoder: &mut DirectoryEncoder<'a, W, K>,
+        value: &[T::Inner],
+    ) -> TiffResult<(K::OffsetType, K::OffsetType)>
+    where
+        [T::Inner]: TiffValue,
+    {
+        let data = value.data();
+        {
+            let mut encoder = ZlibEncoder::new(&mut self.buffer, self.level);
+            encoder.write_all(&data)?;
+            encoder.finish()?;
+        }
+
+        let compressed_byte_count = self.buffer.len().try_into()?;
+        let offset = encoder
+            .write_data(self.buffer.as_slice())
+            .and_then(K::convert_offset)?;
+
+        // Clear the buffer for the next compression.
+        self.buffer.clear();
+
+        Ok((offset, compressed_byte_count))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::encoder::compression::tests::{compress, TEST_DATA};
+
+    #[test]
+    fn test_deflate() {
+        const EXPECTED_COMPRESSED_DATA: [u8; 64] = [
+            0x78, 0x9C, 0x15, 0xC7, 0xD1, 0x0D, 0x80, 0x20, 0x0C, 0x04, 0xD0, 0x55, 0x6E, 0x02,
+            0xA7, 0x71, 0x81, 0xA6, 0x41, 0xDA, 0x28, 0xD4, 0xF4, 0xD0, 0xF9, 0x81, 0xE4, 0xFD,
+            0xBC, 0xD3, 0x9C, 0x58, 0x04, 0x1C, 0xE9, 0xBD, 0xE2, 0x8A, 0x84, 0x5A, 0xD1, 0x7B,
+            0xE7, 0x97, 0xF4, 0xF8, 0x08, 0x8D, 0xF6, 0x66, 0x21, 0x3D, 0x3A, 0xE4, 0xA9, 0x91,
+            0x3E, 0xAC, 0xF1, 0x98, 0xB9, 0x70, 0x17, 0x13,
+        ];
+
+        let compressed_data = compress(TEST_DATA, super::Deflate::default());
+        assert_eq!(compressed_data, EXPECTED_COMPRESSED_DATA);
+    }
+}

src/encoder/compression/lzw.rs

@@ -0,0 +1,79 @@
+use std::{
+    convert::TryInto,
+    io::{Seek, Write},
+};
+
+use weezl::encode::Encoder as LZWEncoder;
+
+use crate::{
+    encoder::{
+        colortype::ColorType, compression::Compression, DirectoryEncoder, TiffKind, TiffValue,
+    },
+    tags::CompressionMethod,
+    TiffResult,
+};
+
+/// The LZW algorithm used to compress image data in TIFF files.
+#[derive(Debug, Clone)]
+pub struct Lzw {
+    buffer: Vec<u8>,
+}
+
+impl Default for Lzw {
+    fn default() -> Self {
+        // Lets be greedy and allocate more bytes in advance. We will likely encode longer image strips.
+        const DEFAULT_BUFFER_SIZE: usize = 256;
+        Self {
+            buffer: Vec::with_capacity(DEFAULT_BUFFER_SIZE),
+        }
+    }
+}
+
+impl Compression for Lzw {
+    const COMPRESSION_METHOD: CompressionMethod = CompressionMethod::LZW;
+
+    fn write_to<'a, T: ColorType, K: TiffKind, W: 'a + Write + Seek>(
+        &mut self,
+        encoder: &mut DirectoryEncoder<'a, W, K>,
+        value: &[T::Inner],
+    ) -> TiffResult<(K::OffsetType, K::OffsetType)>
+    where
+        [T::Inner]: TiffValue,
+    {
+        let bytes = value.data();
+        let compressed_byte_count = {
+            let mut encoder = LZWEncoder::with_tiff_size_switch(weezl::BitOrder::Msb, 8);
+            let result = encoder.into_vec(&mut self.buffer).encode_all(&bytes);
+            result.status.map(|_| result.consumed_out)
+        }?
+        .try_into()?;
+
+        let offset = encoder
+            .write_data(self.buffer.as_slice())
+            .and_then(K::convert_offset)?;
+
+        // Clear the buffer for the next compression.
+        self.buffer.clear();
+
+        Ok((offset, compressed_byte_count))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::encoder::compression::tests::{compress, TEST_DATA};
+
+    #[test]
+    fn test_lzw() {
+        const EXPECTED_COMPRESSED_DATA: [u8; 63] = [
+            0x80, 0x15, 0x0D, 0x06, 0x93, 0x98, 0x82, 0x08, 0x20, 0x30, 0x88, 0x0E, 0x67, 0x43,
+            0x91, 0xA4, 0xDC, 0x67, 0x10, 0x19, 0x8D, 0xE7, 0x21, 0x01, 0x8C, 0xD0, 0x65, 0x31,
+            0x9A, 0xE1, 0xD1, 0x03, 0xB1, 0x86, 0x1A, 0x6F, 0x3A, 0xC1, 0x4C, 0x66, 0xF3, 0x69,
+            0xC0, 0xE4, 0x65, 0x39, 0x9C, 0xCD, 0x26, 0xF3, 0x74, 0x20, 0xD8, 0x67, 0x89, 0x9A,
+            0x4E, 0x86, 0x83, 0x69, 0xCC, 0x5D, 0x01,
+        ];
+
+        let compressed_data = compress(TEST_DATA, super::Lzw::default());
+        assert_eq!(compressed_data, EXPECTED_COMPRESSED_DATA);
+    }
+}

src/encoder/compression/mod.rs

@@ -0,0 +1,58 @@
+use std::io::prelude::*;
+
+use crate::{
+    encoder::{ColorType, DirectoryEncoder, TiffKind, TiffValue},
+    error::TiffResult,
+    tags::CompressionMethod,
+};
+
+mod deflate;
+mod lzw;
+mod uncompressed;
+
+pub use self::deflate::{Deflate, DeflateLevel};
+pub use self::lzw::Lzw;
+pub use self::uncompressed::Uncompressed;
+
+/// An algorithm used for compression with associated optional buffers and/or configurations.
+pub trait Compression: Default {
+    /// The corresponding tag to the algorithm.
+    const COMPRESSION_METHOD: CompressionMethod;
+
+    /// Write the data of a specific color type to the given encoder and return the offset and byte count, respectively.
+    fn write_to<'a, T: ColorType, K: TiffKind, W: 'a + Write + Seek>(
+        &mut self,
+        encoder: &mut DirectoryEncoder<'a, W, K>,
+        value: &[T::Inner],
+    ) -> TiffResult<(K::OffsetType, K::OffsetType)>
+    where
+        [T::Inner]: TiffValue;
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::encoder::{colortype::Gray8, compression::Compression, TiffEncoder};
+    use std::io::Cursor;
+
+    pub const TEST_DATA: &'static [u8] =
+        b"This is a string for checking various compression algorithms.";
+
+    pub fn compress<C: Compression>(data: &[u8], compressor: C) -> Vec<u8> {
+        let mut buffer = Vec::new();
+
+        // Compress the data
+        {
+            let mut encoder = TiffEncoder::new(Cursor::new(&mut buffer)).unwrap();
+            let encoder = encoder
+                .new_image_with_compression::<Gray8, _>(data.len() as u32, 1, compressor)
+                .unwrap();
+            encoder.write_data(&data).unwrap();
+        }
+
+        // Remove the meta data written by the encoder
+        buffer.drain(..8);
+        buffer.drain(buffer.len() - 178..);
+
+        buffer
+    }
+}

src/encoder/compression/uncompressed.rs

@@ -0,0 +1,44 @@
+use std::{
+    convert::TryInto,
+    io::{Seek, Write},
+};
+
+use crate::{
+    encoder::{
+        colortype::ColorType, compression::Compression, DirectoryEncoder, TiffKind, TiffValue,
+    },
+    tags::CompressionMethod,
+    TiffResult,
+};
+
+/// The default algorithm which does not compress at all.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub struct Uncompressed;
+
+impl Compression for Uncompressed {
+    const COMPRESSION_METHOD: CompressionMethod = CompressionMethod::None;
+
+    fn write_to<'a, T: ColorType, K: TiffKind, W: 'a + Write + Seek>(
+        &mut self,
+        encoder: &mut DirectoryEncoder<'a, W, K>,
+        value: &[T::Inner],
+    ) -> TiffResult<(K::OffsetType, K::OffsetType)>
+    where
+        [T::Inner]: TiffValue,
+    {
+        let byte_count = value.len().try_into()?;
+        let offset = encoder.write_data(value).and_then(K::convert_offset)?;
+        Ok((offset, byte_count))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::encoder::compression::tests::{compress, TEST_DATA};
+
+    #[test]
+    fn test_no_compression() {
+        let compressed_data = compress(TEST_DATA, super::Uncompressed);
+        assert_eq!(TEST_DATA, compressed_data);
+    }
+}

src/encoder/mod.rs

@@ -12,14 +12,16 @@ use std::{
 
 use crate::{
     error::TiffResult,
-    tags::{self, ResolutionUnit, Tag},
+    tags::{ResolutionUnit, Tag},
 };
 
 pub mod colortype;
+pub mod compression;
 mod tiff_value;
 mod writer;
 
 use self::colortype::*;
+use self::compression::*;
 use self::writer::*;
 
 /// Encoder for Tiff and BigTiff files.
@@ -98,11 +100,22 @@ impl<W: Write + Seek, K: TiffKind> TiffEncoder<W, K> {
         &mut self,
         width: u32,
         height: u32,
-    ) -> TiffResult<ImageEncoder<W, C, K>> {
+    ) -> TiffResult<ImageEncoder<W, C, K, Uncompressed>> {
         let encoder = DirectoryEncoder::new(&mut self.writer)?;
         ImageEncoder::new(encoder, width, height)
     }
 
+    /// Create an [`ImageEncoder`] to encode an image one slice at a time.
+    pub fn new_image_with_compression<C: ColorType, D: Compression>(
+        &mut self,
+        width: u32,
+        height: u32,
+        compression: D,
+    ) -> TiffResult<ImageEncoder<W, C, K, D>> {
+        let encoder = DirectoryEncoder::new(&mut self.writer)?;
+        ImageEncoder::with_compression(encoder, width, height, compression)
+    }
+
     /// Convenience function to write an entire image from memory.
     pub fn write_image<C: ColorType>(
         &mut self,
@@ -117,6 +130,23 @@ impl<W: Write + Seek, K: TiffKind> TiffEncoder<W, K> {
         let image: ImageEncoder<W, C, K> = ImageEncoder::new(encoder, width, height)?;
         image.write_data(data)
     }
+
+    /// Convenience function to write an entire image from memory with a given compression.
+    pub fn write_image_with_compression<C: ColorType, D: Compression>(
+        &mut self,
+        width: u32,
+        height: u32,
+        compression: D,
+        data: &[C::Inner],
+    ) -> TiffResult<()>
+    where
+        [C::Inner]: TiffValue,
+    {
+        let encoder = DirectoryEncoder::new(&mut self.writer)?;
+        let image: ImageEncoder<W, C, K, D> =
+            ImageEncoder::with_compression(encoder, width, height, compression)?;
+        image.write_data(data)
+    }
 }
 
 /// Low level interface to encode ifd directories.
@@ -277,7 +307,13 @@ impl<'a, W: Write + Seek, K: TiffKind> Drop for DirectoryEncoder<'a, W, K> {
 /// # }
 /// ```
 /// You can also call write_data function wich will encode by strip and finish
-pub struct ImageEncoder<'a, W: 'a + Write + Seek, C: ColorType, K: TiffKind> {
+pub struct ImageEncoder<
+    'a,
+    W: 'a + Write + Seek,
+    C: ColorType,
+    K: TiffKind,
+    D: Compression = Uncompressed,
+> {
     encoder: DirectoryEncoder<'a, W, K>,
     strip_idx: u64,
     strip_count: u64,
@@ -288,11 +324,26 @@ pub struct ImageEncoder<'a, W: 'a + Write + Seek, C: ColorType, K: TiffKind> {
     strip_offsets: Vec<K::OffsetType>,
     strip_byte_count: Vec<K::OffsetType>,
     dropped: bool,
+    compression: D,
     _phantom: ::std::marker::PhantomData<C>,
 }
 
-impl<'a, W: 'a + Write + Seek, T: ColorType, K: TiffKind> ImageEncoder<'a, W, T, K> {
-    fn new(mut encoder: DirectoryEncoder<'a, W, K>, width: u32, height: u32) -> TiffResult<Self> {
+impl<'a, W: 'a + Write + Seek, T: ColorType, K: TiffKind, D: Compression>
+    ImageEncoder<'a, W, T, K, D>
+{
+    fn new(encoder: DirectoryEncoder<'a, W, K>, width: u32, height: u32) -> TiffResult<Self>
+    where
+        D: Default,
+    {
+        Self::with_compression(encoder, width, height, D::default())
+    }
+
+    fn with_compression(
+        mut encoder: DirectoryEncoder<'a, W, K>,
+        width: u32,
+        height: u32,
+        compression: D,
+    ) -> TiffResult<Self> {
         let row_samples = u64::from(width) * u64::try_from(<T>::BITS_PER_SAMPLE.len())?;
         let row_bytes = row_samples * u64::from(<T::Inner>::BYTE_LEN);
 
@@ -304,7 +355,7 @@ impl<'a, W: 'a + Write + Seek, T: ColorType, K: TiffKind> ImageEncoder<'a, W, T,
 
         encoder.write_tag(Tag::ImageWidth, width)?;
         encoder.write_tag(Tag::ImageLength, height)?;
-        encoder.write_tag(Tag::Compression, tags::CompressionMethod::None.to_u16())?;
+        encoder.write_tag(Tag::Compression, D::COMPRESSION_METHOD.to_u16())?;
 
         encoder.write_tag(Tag::BitsPerSample, <T>::BITS_PER_SAMPLE)?;
         let sample_format: Vec<_> = <T>::SAMPLE_FORMAT.iter().map(|s| s.to_u16()).collect();
@@ -332,6 +383,7 @@ impl<'a, W: 'a + Write + Seek, T: ColorType, K: TiffKind> ImageEncoder<'a, W, T,
             strip_offsets: Vec::new(),
             strip_byte_count: Vec::new(),
             dropped: false,
+            compression,
             _phantom: ::std::marker::PhantomData,
         })
     }
@@ -354,7 +406,6 @@ impl<'a, W: 'a + Write + Seek, T: ColorType, K: TiffKind> ImageEncoder<'a, W, T,
     where
         [T::Inner]: TiffValue,
     {
-        // TODO: Compression
         let samples = self.next_strip_sample_count();
         if u64::try_from(value.len())? != samples {
             return Err(io::Error::new(
@@ -364,9 +415,12 @@ impl<'a, W: 'a + Write + Seek, T: ColorType, K: TiffKind> ImageEncoder<'a, W, T,
             .into());
         }
 
-        let offset = self.encoder.write_data(value)?;
-        self.strip_offsets.push(K::convert_offset(offset)?);
-        self.strip_byte_count.push(value.bytes().try_into()?);
+        // Write the (possible compressed) data to the encoder.
+        let (offset, byte_count) = self
+            .compression
+            .write_to::<T, K, W>(&mut self.encoder, value)?;
+        self.strip_offsets.push(offset);
+        self.strip_byte_count.push(byte_count);
 
         self.strip_idx += 1;
         Ok(())
@@ -475,7 +529,9 @@ impl<'a, W: 'a + Write + Seek, T: ColorType, K: TiffKind> ImageEncoder<'a, W, T,
     }
 }
 
-impl<'a, W: Write + Seek, C: ColorType, K: TiffKind> Drop for ImageEncoder<'a, W, C, K> {
+impl<'a, W: Write + Seek, C: ColorType, K: TiffKind, D: Compression> Drop
+    for ImageEncoder<'a, W, C, K, D>
+{
     fn drop(&mut self) {
         if !self.dropped {
             let _ = self.finish_internal();

src/encoder/tiff_value.rs

@@ -1,4 +1,4 @@
-use std::io::Write;
+use std::{borrow::Cow, io::Write};
 
 use crate::{bytecast, tags::Type, TiffError, TiffFormatError, TiffResult};
 
@@ -12,7 +12,18 @@ pub trait TiffValue {
     fn bytes(&self) -> usize {
         self.count() * usize::from(Self::BYTE_LEN)
     }
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()>;
+
+    /// Access this value as an contiguous sequence of bytes.
+    /// If their is no trivial representation, allocate it on the heap.
+    fn data(&self) -> Cow<[u8]>;
+
+    /// Write this value to a TiffWriter.
+    /// While the default implementation will work in all cases, it may require unnecessary allocations.
+    /// The written bytes of any custom implementation MUST be the same as yielded by `self.data()`.
+    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
+        writer.write_bytes(&self.data())?;
+        Ok(())
+    }
 }
 
 impl TiffValue for [u8] {
@@ -23,9 +34,8 @@ impl TiffValue for [u8] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        writer.write_bytes(self)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(self)
     }
 }
 
@@ -37,10 +47,8 @@ impl TiffValue for [i8] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::i8_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::i8_as_ne_bytes(self))
     }
 }
 
@@ -52,10 +60,8 @@ impl TiffValue for [u16] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::u16_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::u16_as_ne_bytes(self))
     }
 }
 
@@ -67,10 +73,8 @@ impl TiffValue for [i16] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::i16_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::i16_as_ne_bytes(self))
     }
 }
 
@@ -82,10 +86,8 @@ impl TiffValue for [u32] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::u32_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::u32_as_ne_bytes(self))
     }
 }
 
@@ -97,10 +99,8 @@ impl TiffValue for [i32] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::i32_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::i32_as_ne_bytes(self))
     }
 }
 
@@ -112,10 +112,8 @@ impl TiffValue for [u64] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::u64_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::u64_as_ne_bytes(self))
     }
 }
 
@@ -127,10 +125,8 @@ impl TiffValue for [i64] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::i64_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::i64_as_ne_bytes(self))
     }
 }
 
@@ -142,11 +138,9 @@ impl TiffValue for [f32] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        // We write using nativeedian so this sould be safe
-        let slice = bytecast::f32_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        // We write using native endian so this should be safe
+        Cow::Borrowed(bytecast::f32_as_ne_bytes(self))
     }
 }
 
@@ -158,75 +152,9 @@ impl TiffValue for [f64] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        // We write using nativeedian so this sould be safe
-        let slice = bytecast::f64_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
-    }
-}
-
-impl TiffValue for [Ifd] {
-    const BYTE_LEN: u8 = 4;
-    const FIELD_TYPE: Type = Type::IFD;
-
-    fn count(&self) -> usize {
-        self.len()
-    }
-
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        for x in self {
-            x.write(writer)?;
-        }
-        Ok(())
-    }
-}
-
-impl TiffValue for [Ifd8] {
-    const BYTE_LEN: u8 = 8;
-    const FIELD_TYPE: Type = Type::IFD8;
-
-    fn count(&self) -> usize {
-        self.len()
-    }
-
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        for x in self {
-            x.write(writer)?;
-        }
-        Ok(())
-    }
-}
-
-impl TiffValue for [Rational] {
-    const BYTE_LEN: u8 = 8;
-    const FIELD_TYPE: Type = Type::RATIONAL;
-
-    fn count(&self) -> usize {
-        self.len()
-    }
-
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        for x in self {
-            x.write(writer)?;
-        }
-        Ok(())
-    }
-}
-
-impl TiffValue for [SRational] {
-    const BYTE_LEN: u8 = 8;
-    const FIELD_TYPE: Type = Type::SRATIONAL;
-
-    fn count(&self) -> usize {
-        self.len()
-    }
-
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        for x in self {
-            x.write(writer)?;
-        }
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        // We write using native endian so this should be safe
+        Cow::Borrowed(bytecast::f64_as_ne_bytes(self))
     }
 }
 
@@ -242,6 +170,10 @@ impl TiffValue for u8 {
         writer.write_u8(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(vec![*self])
+    }
 }
 
 impl TiffValue for i8 {
@@ -256,6 +188,10 @@ impl TiffValue for i8 {
         writer.write_i8(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for u16 {
@@ -270,6 +206,10 @@ impl TiffValue for u16 {
         writer.write_u16(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for i16 {
@@ -284,6 +224,10 @@ impl TiffValue for i16 {
         writer.write_i16(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for u32 {
@@ -298,6 +242,10 @@ impl TiffValue for u32 {
         writer.write_u32(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for i32 {
@@ -312,6 +260,10 @@ impl TiffValue for i32 {
         writer.write_i32(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for u64 {
@@ -326,6 +278,10 @@ impl TiffValue for u64 {
         writer.write_u64(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for i64 {
@@ -340,6 +296,10 @@ impl TiffValue for i64 {
         writer.write_i64(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for f32 {
@@ -354,6 +314,10 @@ impl TiffValue for f32 {
         writer.write_f32(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for f64 {
@@ -368,6 +332,10 @@ impl TiffValue for f64 {
         writer.write_f64(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for Ifd {
@@ -382,6 +350,13 @@ impl TiffValue for Ifd {
         writer.write_u32(self.0)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned({
+            let dword: [u8; 4] = self.0.to_ne_bytes();
+            dword.to_vec()
+        })
+    }
 }
 
 impl TiffValue for Ifd8 {
@@ -396,6 +371,13 @@ impl TiffValue for Ifd8 {
         writer.write_u64(self.0)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned({
+            let qword: [u8; 8] = self.0.to_ne_bytes();
+            qword.to_vec()
+        })
+    }
 }
 
 impl TiffValue for Rational {
@@ -411,6 +393,14 @@ impl TiffValue for Rational {
         writer.write_u32(self.d)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned({
+            let first_dword: [u8; 4] = self.n.to_ne_bytes();
+            let second_dword: [u8; 4] = self.d.to_ne_bytes();
+            [first_dword, second_dword].concat()
+        })
+    }
 }
 
 impl TiffValue for SRational {
@@ -426,6 +416,14 @@ impl TiffValue for SRational {
         writer.write_i32(self.d)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned({
+            let first_dword: [u8; 4] = self.n.to_ne_bytes();
+            let second_dword: [u8; 4] = self.d.to_ne_bytes();
+            [first_dword, second_dword].concat()
+        })
+    }
 }
 
 impl TiffValue for str {
@@ -445,6 +443,17 @@ impl TiffValue for str {
             Err(TiffError::FormatError(TiffFormatError::InvalidTag))
         }
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned({
+            if self.is_ascii() && !self.bytes().any(|b| b == 0) {
+                let bytes: &[u8] = self.as_bytes();
+                [bytes, &[0]].concat()
+            } else {
+                vec![]
+            }
+        })
+    }
 }
 
 impl<'a, T: TiffValue + ?Sized> TiffValue for &'a T {
@@ -458,7 +467,44 @@ impl<'a, T: TiffValue + ?Sized> TiffValue for &'a T {
     fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
         (*self).write(writer)
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        T::data(self)
     }
+}
+
+macro_rules! impl_tiff_value_for_contiguous_sequence {
+    ($inner_type:ty; $bytes:expr; $field_type:expr) => {
+        impl $crate::encoder::TiffValue for [$inner_type] {
+            const BYTE_LEN: u8 = $bytes;
+            const FIELD_TYPE: Type = $field_type;
+
+            fn count(&self) -> usize {
+                self.len()
+            }
+
+            fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
+                for x in self {
+                    x.write(writer)?;
+                }
+                Ok(())
+            }
+
+            fn data(&self) -> Cow<[u8]> {
+                let mut buf: Vec<u8> = Vec::with_capacity(Self::BYTE_LEN as usize * self.len());
+                for x in self {
+                    buf.extend_from_slice(&x.data());
+                }
+                Cow::Owned(buf)
+            }
+        }
+    };
+}
+
+impl_tiff_value_for_contiguous_sequence!(Ifd; 4; Type::IFD);
+impl_tiff_value_for_contiguous_sequence!(Ifd8; 8; Type::IFD8);
+impl_tiff_value_for_contiguous_sequence!(Rational; 8; Type::RATIONAL);
+impl_tiff_value_for_contiguous_sequence!(SRational; 8; Type::SRATIONAL);
 
 /// Type to represent tiff values of type `IFD`
 #[derive(Clone)]

src/error.rs

@@ -10,6 +10,8 @@ use crate::tags::{
 };
 use crate::ColorType;
 
+use crate::weezl::LzwError;
+
 /// Tiff error kinds.
 #[derive(Debug)]
 pub enum TiffError {
@@ -31,6 +33,9 @@ pub enum TiffError {
 
     /// The image does not support the requested operation
     UsageError(UsageError),
+
+    /// An error has occurred during data compression
+    CompressionError,
 }
 
 /// The image is not formatted properly.
@@ -228,6 +233,7 @@ impl fmt::Display for TiffError {
             TiffError::LimitsExceeded => write!(fmt, "The Decoder limits are exceeded"),
             TiffError::IntSizeError => write!(fmt, "Platform or format size limits exceeded"),
             TiffError::UsageError(ref e) => write!(fmt, "Usage error: {}", e),
+            TiffError::CompressionError => write!(fmt, "Compression failed"),
         }
     }
 }
@@ -241,6 +247,7 @@ impl Error for TiffError {
             TiffError::LimitsExceeded => "Decoder limits exceeded",
             TiffError::IntSizeError => "Platform or format size limits exceeded",
             TiffError::UsageError(..) => "Invalid usage",
+            TiffError::CompressionError => "Compression failed",
         }
     }
 
@@ -288,5 +295,11 @@ impl From<std::num::TryFromIntError> for TiffError {
     }
 }
 
+impl From<LzwError> for TiffError {
+    fn from(_err: LzwError) -> TiffError {
+        TiffError::CompressionError
+    }
+}
+
 /// Result of an image decoding/encoding process
 pub type TiffResult<T> = Result<T, TiffError>;

tests/encode_images_with_compression.rs

@@ -0,0 +1,137 @@
+extern crate tiff;
+
+use std::io::Cursor;
+use tiff::{
+    decoder::{Decoder, DecodingResult},
+    encoder::{colortype, compression::*, TiffEncoder},
+    tags::Tag,
+};
+
+trait TestImage {
+    const WIDTH: u32;
+    const HEIGHT: u32;
+    type PixelType;
+
+    fn generate() -> Vec<Self::PixelType>;
+}
+
+struct TestImageColor;
+impl TestImage for TestImageColor {
+    const WIDTH: u32 = 1;
+    const HEIGHT: u32 = 7;
+    type PixelType = u16;
+
+    fn generate() -> Vec<Self::PixelType> {
+        let mut data: Vec<u16> = Vec::with_capacity((Self::WIDTH * Self::HEIGHT) as usize * 3);
+        for x in 0..Self::WIDTH {
+            for y in 0..Self::HEIGHT {
+                let val = (x + y) % Self::PixelType::MAX as u32;
+                data.extend(std::iter::repeat(val as Self::PixelType).take(3));
+            }
+        }
+        assert_eq!(data.len() as u32, Self::WIDTH * Self::HEIGHT * 3);
+        data
+    }
+}
+
+struct TestImageGrayscale;
+impl TestImage for TestImageGrayscale {
+    const WIDTH: u32 = 21;
+    const HEIGHT: u32 = 10;
+    type PixelType = u8;
+
+    fn generate() -> Vec<Self::PixelType> {
+        let mut data: Vec<u8> = Vec::with_capacity((Self::WIDTH * Self::HEIGHT) as usize);
+        for x in 0..Self::WIDTH {
+            for y in 0..Self::HEIGHT {
+                let val = (x + y) % Self::PixelType::MAX as u32;
+                data.push(val as Self::PixelType);
+            }
+        }
+        assert_eq!(data.len() as u32, Self::WIDTH * Self::HEIGHT);
+        data
+    }
+}
+
+fn encode_decode_with_compression<C: Compression + Clone>(compression: C) {
+    let mut data = Cursor::new(Vec::new());
+
+    let image_data_rgb = TestImageColor::generate();
+    let image_data_gray = TestImageGrayscale::generate();
+
+    // Encode tiff with compression
+    {
+        // Create a multipage image with 2 images
+        let mut encoder = TiffEncoder::new(&mut data).unwrap();
+
+        // Write first colored image
+        let image_rgb = encoder
+            .new_image_with_compression::<colortype::RGB16, C>(
+                TestImageColor::WIDTH,
+                TestImageColor::HEIGHT,
+                compression.clone(),
+            )
+            .unwrap();
+        image_rgb.write_data(&image_data_rgb).unwrap();
+
+        // Write second grayscale image
+        let image_gray = encoder
+            .new_image_with_compression::<colortype::Gray8, C>(
+                TestImageGrayscale::WIDTH,
+                TestImageGrayscale::HEIGHT,
+                compression,
+            )
+            .unwrap();
+        image_gray.write_data(&image_data_gray).unwrap();
+    }
+
+    // Decode tiff
+    data.set_position(0);
+    {
+        let mut decoder = Decoder::new(data).unwrap();
+
+        // Check the RGB image
+        assert_eq!(
+            decoder
+                .get_tag(Tag::ImageWidth)
+                .unwrap()
+                .into_u32()
+                .unwrap(),
+            TestImageColor::WIDTH
+        );
+        assert_eq!(
+            match decoder.read_image() {
+                Ok(DecodingResult::U16(image_data)) => image_data,
+                unexpected => panic!("Descoding RGB failed: {:?}", unexpected),
+            },
+            image_data_rgb
+        );
+
+        // Check the grayscale image
+        decoder.next_image().unwrap();
+        assert_eq!(
+            match decoder.read_image() {
+                Ok(DecodingResult::U8(image_data)) => image_data,
+                unexpected => panic!("Decoding grayscale failed: {:?}", unexpected),
+            },
+            image_data_gray
+        );
+    }
+}
+
+#[test]
+fn encode_decode_without_compression() {
+    encode_decode_with_compression(Uncompressed);
+}
+
+#[test]
+fn encode_decode_with_lzw() {
+    encode_decode_with_compression(Lzw::default());
+}
+
+#[test]
+fn encode_decode_with_deflate() {
+    encode_decode_with_compression(Deflate::with_level(DeflateLevel::Fast));
+    encode_decode_with_compression(Deflate::with_level(DeflateLevel::Balanced));
+    encode_decode_with_compression(Deflate::with_level(DeflateLevel::Best));
+}