feat: Include Endianness as property of TIFF struct (#149)

Author: kylebarron

python/python/async_tiff/_tiff.pyi

@@ -1,11 +1,13 @@
 from typing import Protocol
-from ._tile import Tile
-from ._ifd import ImageFileDirectory
-from .store import ObjectStore
 
 # Fix exports
 from obspec._get import GetRangeAsync, GetRangesAsync
 
+from ._ifd import ImageFileDirectory
+from ._tile import Tile
+from .enums import Endianness
+from .store import ObjectStore
+
 class ObspecInput(GetRangeAsync, GetRangesAsync, Protocol):
     """Supported obspec input to reader."""
 
@@ -33,6 +35,10 @@ class TIFF:
         Returns:
             A TIFF instance.
         """
+
+    @property
+    def endianness(self) -> Endianness:
+        """The endianness of this TIFF file."""
     @property
     def ifds(self) -> list[ImageFileDirectory]:
         """Access the underlying IFDs of this TIFF.

python/python/async_tiff/enums.py

@@ -21,6 +21,11 @@ class CompressionMethod(IntEnum):
     PackBits = 0x8005
 
 
+class Endianness(IntEnum):
+    LittleEndian = 0
+    BigEndian = 1
+
+
 class PhotometricInterpretation(IntEnum):
     WhiteIsZero = 0
     BlackIsZero = 1

python/src/enums.rs

@@ -1,3 +1,4 @@
+use async_tiff::reader::Endianness;
 use async_tiff::tiff::tags::{
     CompressionMethod, PhotometricInterpretation, PlanarConfiguration, Predictor, ResolutionUnit,
     SampleFormat,
@@ -39,6 +40,30 @@ impl<'py> IntoPyObject<'py> for PyCompressionMethod {
     }
 }
 
+pub(crate) struct PyEndianness(Endianness);
+
+impl From<Endianness> for PyEndianness {
+    fn from(value: Endianness) -> Self {
+        Self(value)
+    }
+}
+
+impl<'py> IntoPyObject<'py> for PyEndianness {
+    type Target = PyAny;
+    type Output = Bound<'py, PyAny>;
+    type Error = PyErr;
+
+    fn into_pyobject(self, py: Python<'py>) -> Result<Self::Output, Self::Error> {
+        let enums_mod = py.import(intern!(py, "async_tiff.enums"))?;
+        let endianness_enum = enums_mod.getattr(intern!(py, "Endianness"))?;
+
+        match self.0 {
+            Endianness::LittleEndian => endianness_enum.getattr("LittleEndian"),
+            Endianness::BigEndian => endianness_enum.getattr("BigEndian"),
+        }
+    }
+}
+
 pub(crate) struct PyPhotometricInterpretation(PhotometricInterpretation);
 
 impl From<PhotometricInterpretation> for PyPhotometricInterpretation {
@@ -132,6 +157,7 @@ impl<'py> IntoPyObject<'py> for PySampleFormat {
         to_py_enum_variant(py, intern!(py, "SampleFormat"), self.0.to_u16())
     }
 }
+
 fn to_py_enum_variant<'py>(
     py: Python<'py>,
     enum_name: &Bound<'py, PyString>,

python/src/tiff.rs

@@ -9,6 +9,7 @@ use pyo3::prelude::*;
 use pyo3::types::PyType;
 use pyo3_async_runtimes::tokio::future_into_py;
 
+use crate::enums::PyEndianness;
 use crate::error::PyAsyncTiffResult;
 use crate::reader::StoreInput;
 use crate::tile::PyTile;
@@ -29,8 +30,7 @@ async fn open(
         .with_initial_size(prefetch)
         .with_multiplier(multiplier);
     let mut metadata_reader = TiffMetadataReader::try_open(&metadata_fetch).await?;
-    let ifds = metadata_reader.read_all_ifds(&metadata_fetch).await?;
-    let tiff = TIFF::new(ifds);
+    let tiff = metadata_reader.read(&metadata_fetch).await?;
     Ok(PyTIFF { tiff, reader })
 }
 
@@ -56,6 +56,11 @@ impl PyTIFF {
         Ok(cog_reader)
     }
 
+    #[getter]
+    fn endianness(&self) -> PyEndianness {
+        self.tiff.endianness().into()
+    }
+
     #[getter]
     fn ifds(&self) -> Vec<PyImageFileDirectory> {
         let ifds = self.tiff.ifds();

python/tests/test_cog.py

@@ -13,6 +13,8 @@ async def test_cog_s3():
     store = S3Store("sentinel-cogs", region="us-west-2", skip_signature=True)
     tiff = await TIFF.open(path=path, store=store)
 
+    assert tiff.endianness == enums.Endianness.LittleEndian
+
     ifds = tiff.ifds
     assert len(ifds) == 5
 

src/cog.rs

@@ -1,21 +1,28 @@
 use crate::ifd::ImageFileDirectory;
+use crate::reader::Endianness;
 
 /// A TIFF file.
 #[derive(Debug, Clone)]
 pub struct TIFF {
+    endianness: Endianness,
     ifds: Vec<ImageFileDirectory>,
 }
 
 impl TIFF {
     /// Create a new TIFF from existing IFDs.
-    pub fn new(ifds: Vec<ImageFileDirectory>) -> Self {
-        Self { ifds }
+    pub fn new(ifds: Vec<ImageFileDirectory>, endianness: Endianness) -> Self {
+        Self { ifds, endianness }
     }
 
     /// Access the underlying Image File Directories.
     pub fn ifds(&self) -> &[ImageFileDirectory] {
         &self.ifds
     }
+
+    /// Get the endianness of the TIFF file.
+    pub fn endianness(&self) -> Endianness {
+        self.endianness
+    }
 }
 
 #[cfg(test)]
@@ -41,7 +48,7 @@ mod test {
         let cached_reader = ReadaheadMetadataCache::new(reader.clone());
         let mut metadata_reader = TiffMetadataReader::try_open(&cached_reader).await.unwrap();
         let ifds = metadata_reader.read_all_ifds(&cached_reader).await.unwrap();
-        let tiff = TIFF::new(ifds);
+        let tiff = TIFF::new(ifds, metadata_reader.endianness());
 
         let ifd = &tiff.ifds[1];
         let tile = ifd.fetch_tile(0, 0, reader.as_ref()).await.unwrap();

src/metadata/reader.rs

@@ -9,7 +9,7 @@ use crate::metadata::MetadataFetch;
 use crate::reader::Endianness;
 use crate::tiff::tags::{Tag, Type};
 use crate::tiff::{TiffError, TiffFormatError, Value};
-use crate::ImageFileDirectory;
+use crate::{ImageFileDirectory, TIFF};
 
 /// Entry point to reading TIFF metadata.
 ///
@@ -135,6 +135,12 @@ impl TiffMetadataReader {
         }
         Ok(ifds)
     }
+
+    /// Read all IFDs from the file and return a complete TIFF structure.
+    pub async fn read<F: MetadataFetch>(&mut self, fetch: &F) -> AsyncTiffResult<TIFF> {
+        let ifds = self.read_all_ifds(fetch).await?;
+        Ok(TIFF::new(ifds, self.endianness))
+    }
 }
 
 /// Reads the [`ImageFileDirectory`] metadata.

tests/image_tiff/util.rs

@@ -14,6 +14,5 @@ pub(crate) async fn open_tiff(filename: &str) -> TIFF {
     let reader = Arc::new(ObjectReader::new(store.clone(), path.as_str().into()))
         as Arc<dyn AsyncFileReader>;
     let mut metadata_reader = TiffMetadataReader::try_open(&reader).await.unwrap();
-    let ifds = metadata_reader.read_all_ifds(&reader).await.unwrap();
-    TIFF::new(ifds)
+    metadata_reader.read(&reader).await.unwrap()
 }

tests/ome_tiff.rs

@@ -16,8 +16,7 @@ async fn open_remote_tiff(url: &str) -> TIFF {
     let reader = Arc::new(ObjectReader::new(Arc::new(store), path)) as Arc<dyn AsyncFileReader>;
     let cached_reader = ReadaheadMetadataCache::new(reader.clone());
     let mut metadata_reader = TiffMetadataReader::try_open(&cached_reader).await.unwrap();
-    let ifds = metadata_reader.read_all_ifds(&cached_reader).await.unwrap();
-    TIFF::new(ifds)
+    metadata_reader.read(&cached_reader).await.unwrap()
 }
 
 #[tokio::test]