Add TIFF compression and corresponding tests

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);
+    }
+}