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Expose Decoder::seek_to_directory

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A. Molzer committed 2026-03-04 08:59:41 +01:00
1 parent 4ff88e658d
commit cf8f96568e
1 file changed
+62 -40
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src/decoder/mod.rs
+62 -40
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@@ -827,7 +827,14 @@ impl<R: Read + Seek> Decoder<R> {
current_ifd_pointer: None,
directory: Directory::empty(),
seen_ifds: cycles::IfdCycles::new(),
image: Image {
image: Self::no_image(),
};
decoder.next_image()?;
Ok(decoder)
}
fn no_image() -> Image {
Image {
width: 0,
height: 0,
bits_per_sample: 1,
@@ -847,10 +854,7 @@ impl<R: Read + Seek> Decoder<R> {
chunk_bytes: Vec::new(),
chroma_subsampling: (2, 2),
decompression_to_host_endian: false,
},
};
decoder.next_image()?;
Ok(decoder)
}
}
pub fn with_limits(mut self, limits: Limits) -> Decoder<R> {
@@ -859,11 +863,11 @@ impl<R: Read + Seek> Decoder<R> {
}
pub fn dimensions(&mut self) -> TiffResult<(u32, u32)> {
Ok((self.image().width, self.image().height))
Ok((self.image.width, self.image.height))
}
pub fn colortype(&mut self) -> TiffResult<ColorType> {
self.image().colortype()
self.image.colortype()
}
/// The offset of the directory representing the current image.
@@ -871,12 +875,21 @@ impl<R: Read + Seek> Decoder<R> {
self.current_ifd_pointer
}
fn image(&self) -> &Image {
&self.image
/// Loads the IFD at the specified index in the list, if one exists
pub fn seek_to_directory(&mut self, ifd_index: usize) -> TiffResult<()> {
self.seek_to_ifd(ifd_index)
}
/// Loads the IFD at the specified index in the list, if one exists
///
/// The directory is then decoded as an image.
pub fn seek_to_image(&mut self, ifd_index: usize) -> TiffResult<()> {
self.seek_to_ifd(ifd_index)?;
self.image = Image::from_reader(&mut self.value_reader, &self.directory)?;
Ok(())
}
fn seek_to_ifd(&mut self, ifd_index: usize) -> TiffResult<()> {
// Check whether we have seen this IFD before, if so then the index will be less than the
// length of the list of ifd offsets If the index is within the list of ifds then we can
// load the selected image/IFD. Otherwise we iterate the chain until the selected index.
@@ -906,7 +919,6 @@ impl<R: Read + Seek> Decoder<R> {
}
// Reaching this point implies `self.directory` represents the selected ifd.
self.image = Image::from_reader(&mut self.value_reader, &self.directory)?;
Ok(())
}
@@ -934,7 +946,17 @@ impl<R: Read + Seek> Decoder<R> {
Ok(())
}
/// Reads the next IFD.
///
/// If there is no further image in the TIFF file a format error is returned.
/// To determine whether there are more images call `TIFFDecoder::more_images` instead.
pub fn next_directory(&mut self) -> TiffResult<()> {
self.image = Self::no_image();
self.read_next_ifd_pointer()
}
/// Reads in the next image.
///
/// If there is no further image in the TIFF file a format error is returned.
/// To determine whether there are more images call `TIFFDecoder::more_images` instead.
pub fn next_image(&mut self) -> TiffResult<()> {
@@ -1094,10 +1116,10 @@ impl<R: Read + Seek> Decoder<R> {
}
fn check_chunk_type(&self, expected: ChunkType) -> TiffResult<()> {
if expected != self.image().chunk_type {
if expected != self.image.chunk_type {
return Err(TiffError::UsageError(UsageError::InvalidChunkType(
expected,
self.image().chunk_type,
self.image.chunk_type,
)));
}
@@ -1106,27 +1128,27 @@ impl<R: Read + Seek> Decoder<R> {
/// The chunk type (Strips / Tiles) of the image
pub fn get_chunk_type(&self) -> ChunkType {
self.image().chunk_type
self.image.chunk_type
}
/// Number of strips in image
pub fn strip_count(&mut self) -> TiffResult<u32> {
self.check_chunk_type(ChunkType::Strip)?;
let rows_per_strip = self.image().strip_decoder.as_ref().unwrap().rows_per_strip;
let rows_per_strip = self.image.strip_decoder.as_ref().unwrap().rows_per_strip;
if rows_per_strip == 0 {
return Ok(0);
}
// rows_per_strip - 1 can never fail since we know it's at least 1
let height = match self.image().height.checked_add(rows_per_strip - 1) {
let height = match self.image.height.checked_add(rows_per_strip - 1) {
Some(h) => h,
None => return Err(TiffError::IntSizeError),
};
let strips = match self.image().planar_config {
let strips = match self.image.planar_config {
PlanarConfiguration::Chunky => height / rows_per_strip,
PlanarConfiguration::Planar => height / rows_per_strip * self.image().samples as u32,
PlanarConfiguration::Planar => height / rows_per_strip * self.image.samples as u32,
};
Ok(strips)
@@ -1135,7 +1157,7 @@ impl<R: Read + Seek> Decoder<R> {
/// Number of tiles in image
pub fn tile_count(&mut self) -> TiffResult<u32> {
self.check_chunk_type(ChunkType::Tile)?;
Ok(u32::try_from(self.image().chunk_offsets.len())?)
Ok(u32::try_from(self.image.chunk_offsets.len())?)
}
fn read_chunk_to_bytes(
@@ -1164,8 +1186,8 @@ impl<R: Read + Seek> Decoder<R> {
&mut self,
chunk_index: u32,
) -> TiffResult<BufferLayoutPreference> {
let data_dims = self.image().chunk_data_dimensions(chunk_index)?;
let readout = self.image().readout_for_size(data_dims.0, data_dims.1)?;
let data_dims = self.image.chunk_data_dimensions(chunk_index)?;
let readout = self.image.readout_for_size(data_dims.0, data_dims.1)?;
let extent = readout.result_extent_for_planes(0..1)?;
let sample_type = extent.sample_type();
@@ -1180,7 +1202,7 @@ impl<R: Read + Seek> Decoder<R> {
planes: 1,
plane_stride,
complete_len: layout.size(),
sample_format: self.image().sample_format,
sample_format: self.image.sample_format,
sample_type: Some(sample_type),
})
}
@@ -1197,15 +1219,15 @@ impl<R: Read + Seek> Decoder<R> {
&mut self,
code_unit: TiffCodingUnit,
) -> TiffResult<BufferLayoutPreference> {
match self.image().planar_config {
match self.image.planar_config {
PlanarConfiguration::Chunky => return self.image_chunk_buffer_layout(code_unit.0),
PlanarConfiguration::Planar => {}
}
let (width, height) = self.image().chunk_data_dimensions(code_unit.0)?;
let (width, height) = self.image.chunk_data_dimensions(code_unit.0)?;
let layout = self
.image()
.image
.readout_for_size(width, height)?
.to_plane_layout()?;
@@ -1223,9 +1245,9 @@ impl<R: Read + Seek> Decoder<R> {
///
/// Note that for planar images each chunk contains only one sample of the underlying data.
pub fn read_chunk(&mut self, chunk_index: u32) -> TiffResult<DecodingResult> {
let (width, height) = self.image().chunk_data_dimensions(chunk_index)?;
let (width, height) = self.image.chunk_data_dimensions(chunk_index)?;
let readout = self.image().readout_for_size(width, height)?;
let readout = self.image.readout_for_size(width, height)?;
let mut result = readout
.result_extent_for_planes(0..1)?
@@ -1244,9 +1266,9 @@ impl<R: Read + Seek> Decoder<R> {
///
/// Note that for planar images each chunk contains only one sample of the underlying data.
pub fn read_chunk_bytes(&mut self, chunk_index: u32, buffer: &mut [u8]) -> TiffResult<()> {
let (width, height) = self.image().chunk_data_dimensions(chunk_index)?;
let (width, height) = self.image.chunk_data_dimensions(chunk_index)?;
let layout = self.image().readout_for_size(width, height)?;
let layout = self.image.readout_for_size(width, height)?;
layout.assert_min_layout(buffer)?;
self.read_chunk_to_bytes(buffer, chunk_index, &layout)?;
@@ -1267,9 +1289,9 @@ impl<R: Read + Seek> Decoder<R> {
chunk_index: u32,
output_width: usize,
) -> TiffResult<()> {
let (width, height) = self.image().chunk_data_dimensions(chunk_index)?;
let (width, height) = self.image.chunk_data_dimensions(chunk_index)?;
let mut layout = self.image().readout_for_size(width, height)?;
let mut layout = self.image.readout_for_size(width, height)?;
layout.set_row_stride(output_width)?;
let extent = layout.result_extent_for_planes(0..1)?;
@@ -1299,8 +1321,8 @@ impl<R: Read + Seek> Decoder<R> {
slice: TiffCodingUnit,
buffer: &mut [u8],
) -> TiffResult<()> {
let (width, height) = self.image().chunk_data_dimensions(slice.0)?;
let readout = self.image().readout_for_size(width, height)?;
let (width, height) = self.image.chunk_data_dimensions(slice.0)?;
let readout = self.image.readout_for_size(width, height)?;
let ref layout @ image::PlaneLayout {
ref plane_offsets,
@@ -1322,7 +1344,7 @@ impl<R: Read + Seek> Decoder<R> {
for (idx, &plane_offset) in plane_offsets[..used_plane_offsets].iter().enumerate() {
let chunk = slice.0 + idx as u32 * readout.chunks_per_plane;
self.goto_offset_u64(self.image().chunk_offsets[chunk as usize])?;
self.goto_offset_u64(self.image.chunk_offsets[chunk as usize])?;
self.image.expand_chunk(
&mut self.value_reader,
@@ -1338,13 +1360,13 @@ impl<R: Read + Seek> Decoder<R> {
/// Returns the default chunk size for the current image. Any given chunk in the image is at most as large as
/// the value returned here. For the size of the data (chunk minus padding), use `chunk_data_dimensions`.
pub fn chunk_dimensions(&self) -> (u32, u32) {
self.image().chunk_dimensions().unwrap()
self.image.chunk_dimensions().unwrap()
}
/// Returns the size of the data in the chunk with the specified index. This is the default size of the chunk,
/// minus any padding.
pub fn chunk_data_dimensions(&self, chunk_index: u32) -> (u32, u32) {
self.image()
self.image
.chunk_data_dimensions(chunk_index)
.expect("invalid chunk_index")
}
@@ -1363,7 +1385,7 @@ impl<R: Read + Seek> Decoder<R> {
/// indicate the layout needed to read the first data plane. This will be fixed in a future
/// major version of `tiff`.
pub fn image_buffer_layout(&mut self) -> TiffResult<BufferLayoutPreference> {
let layout = self.image().readout_for_image()?.to_plane_layout()?;
let layout = self.image.readout_for_image()?.to_plane_layout()?;
Ok(BufferLayoutPreference::from_planes(&layout))
}
@@ -1387,7 +1409,7 @@ impl<R: Read + Seek> Decoder<R> {
/// replaced, to ensure that existing code will not run into unexpectedly large allocations
/// that will error on limits instead.
pub fn read_image(&mut self) -> TiffResult<DecodingResult> {
let readout = self.image().readout_for_image()?;
let readout = self.image.readout_for_image()?;
let mut result = readout
.result_extent_for_planes(0..1)?
@@ -1448,7 +1470,7 @@ impl<R: Read + Seek> Decoder<R> {
&mut self,
result: &mut DecodingResult,
) -> TiffResult<BufferLayoutPreference> {
let readout = self.image().readout_for_image()?;
let readout = self.image.readout_for_image()?;
let planes = readout.to_plane_layout()?;
let num_planes = if planes.total_bytes <= self.value_reader.limits.decoding_buffer_size {
@@ -1479,7 +1501,7 @@ impl<R: Read + Seek> Decoder<R> {
/// Returns an error if the buffer fits less than one plane. In particular, for non-planar
/// images returns an error if the buffer does not fit the required size.
pub fn read_image_bytes(&mut self, buffer: &mut [u8]) -> TiffResult<()> {
let readout = self.image().readout_for_image()?;
let readout = self.image.readout_for_image()?;
let ref layout @ image::PlaneLayout {
ref plane_offsets,
@@ -1503,7 +1525,7 @@ impl<R: Read + Seek> Decoder<R> {
for (idx, &plane_offset) in plane_offsets[..used_plane_offsets].iter().enumerate() {
let chunk = chunk + idx as u32 * readout.chunks_per_plane;
self.goto_offset_u64(self.image().chunk_offsets[chunk as usize])?;
self.goto_offset_u64(self.image.chunk_offsets[chunk as usize])?;
self.image.expand_chunk(
&mut self.value_reader,