/src/image/src/codecs/tiff.rs

Source
//! Decoding and Encoding of TIFF Images
//!
//! TIFF (Tagged Image File Format) is a versatile image format that supports
//! lossless and lossy compression.
//!
//! # Related Links
//! * <http://partners.adobe.com/public/developer/tiff/index.html> - The TIFF specification
use std::io::{BufRead, Seek, Write};

use tiff::decoder::ifd::Value;
use tiff::decoder::{Decoder, DecodingResult};
use tiff::tags::Tag;

use crate::color::{ColorType, ExtendedColorType};
use crate::error::{
    DecodingError, EncodingError, ImageError, ImageResult, LimitError, LimitErrorKind,
    ParameterError, ParameterErrorKind, UnsupportedError, UnsupportedErrorKind,
};
use crate::io::decoder::DecodedMetadataHint;
use crate::io::{DecodedImageAttributes, DecoderPreparedImage, FormatAttributes};
use crate::metadata::Orientation;
use crate::{utils, ImageDecoder, ImageEncoder, ImageFormat};

const TAG_XML_PACKET: Tag = Tag::Unknown(700);
const TAG_YCBCR_COEFFICIENTS: Tag = Tag::Unknown(529);
const TAG_YCBCR_SUBSAMPLING: Tag = Tag::Unknown(530);

/// Decoder for TIFF images.
pub struct TiffDecoder<R>
where
    R: BufRead + Seek,
{
    info: ImageState,
    /// The individual allocations attribute to parts of the decoder.
    limits: tiff::decoder::Limits,
    // We only use an Option here so we can call with_limits on the decoder without moving.
    inner: Option<Decoder<R>>,
    buffer: DecodingResult,
}

enum ImageState {
    Initial,
    At(ImageInfo),
    Consumed,
}

#[derive(Clone, Copy)]
struct ImageInfo {
    dimensions: (u32, u32),
    color_type: ColorType,
    original_color_type: ExtendedColorType,
    ycbcr_coefficients: [f32; 3],
}

impl<R> TiffDecoder<R>
where
    R: BufRead + Seek,
{
    /// Create a new `TiffDecoder`.
    pub fn new(r: R) -> Result<TiffDecoder<R>, ImageError> {
        let inner = Decoder::new(r).map_err(ImageError::from_tiff_decode)?;

        Ok(TiffDecoder {
            info: ImageState::Initial,
            limits: tiff::decoder::Limits::default(),
            inner: Some(inner),
            buffer: DecodingResult::U8(vec![]),
        })
    }

    fn peek_info(&mut self) -> ImageResult<ImageInfo> {
        let Some(reader) = &mut self.inner else {
            return Err(ImageError::Parameter(ParameterError::from_kind(
                ParameterErrorKind::FailedAlready,
            )));
        };

        // This image may have been consumed, we should advance.
        if let ImageState::Consumed = self.info {
            reader.next_image().map_err(ImageError::from_tiff_decode)?;
            self.info = ImageState::Initial;
        }

        if let ImageState::Initial = self.info {
            self.reset_info_from_current_image()?;
        }

        let ImageState::At(info) = self.info else {
            return Err(ImageError::Parameter(ParameterError::from_kind(
                ParameterErrorKind::FailedAlready,
            )));
        };

        Ok(info)
    }

    fn reset_info_from_current_image(&mut self) -> ImageResult<()> {
        use tiff::tags::SampleFormat::{Uint, IEEEFP};

        let Some(reader) = &mut self.inner else {
            return Err(ImageError::Parameter(ParameterError::from_kind(
                ParameterErrorKind::FailedAlready,
            )));
        };

        let dimensions = reader.dimensions().map_err(ImageError::from_tiff_decode)?;
        let tiff_color_type = reader.colortype().map_err(ImageError::from_tiff_decode)?;
        let sample_format = reader
            .image_buffer_layout()
            .map_err(ImageError::from_tiff_decode)?
            .sample_format;

        let color_type = match (tiff_color_type, sample_format) {
            (tiff::ColorType::Gray(1), Uint) => ColorType::L8,
            (tiff::ColorType::Gray(8), Uint) => ColorType::L8,
            (tiff::ColorType::Gray(16), Uint) => ColorType::L16,
            (tiff::ColorType::Gray(32), IEEEFP) => ColorType::L32F,
            (tiff::ColorType::GrayA(8), Uint) => ColorType::La8,
            (tiff::ColorType::GrayA(16), Uint) => ColorType::La16,
            (tiff::ColorType::RGB(8), Uint) => ColorType::Rgb8,
            (tiff::ColorType::RGB(16), Uint) => ColorType::Rgb16,
            (tiff::ColorType::RGBA(8), Uint) => ColorType::Rgba8,
            (tiff::ColorType::RGBA(16), Uint) => ColorType::Rgba16,
            (tiff::ColorType::CMYK(8), Uint) => ColorType::Rgb8,
            (tiff::ColorType::CMYK(16), Uint) => ColorType::Rgb16,
            (tiff::ColorType::RGB(32), IEEEFP) => ColorType::Rgb32F,
            (tiff::ColorType::RGBA(32), IEEEFP) => ColorType::Rgba32F,
            (tiff::ColorType::YCbCr(8), Uint) => ColorType::Rgb8,
            _ => {
                return Err(ImageError::Unsupported(
                    UnsupportedError::from_format_and_kind(
                        ImageFormat::Tiff.into(),
                        UnsupportedErrorKind::GenericFeature(format!(
                            "Unsupported TIFF color {tiff_color_type:?} with sample format {sample_format:?}"
                        )),
                    ),
                ));
            }
        };

        let original_color_type = match (tiff_color_type, sample_format) {
            (tiff::ColorType::Gray(1), Uint) => ExtendedColorType::L1,
            (tiff::ColorType::CMYK(8), Uint) => ExtendedColorType::Cmyk8,
            (tiff::ColorType::CMYK(16), Uint) => ExtendedColorType::Cmyk16,
            (tiff::ColorType::YCbCr(8), Uint) => ExtendedColorType::YCbCr8,
            _ => color_type.into(),
        };

        let mut ycbcr_coefficients = [0.0; 3];
        if matches!(tiff_color_type, tiff::ColorType::YCbCr(8)) {
            check_ycbcr_subsampling(reader)?;
            ycbcr_coefficients = read_ycbcr_coefficients(reader)?;
        }

        self.info = ImageState::At(ImageInfo {
            dimensions,
            color_type,
            original_color_type,
            ycbcr_coefficients,
        });

        self.redistribute_limits();

        Ok(())
    }

    fn redistribute_limits(&mut self) {
        let ImageState::At(info) = &self.info else {
            return;
        };

        if self.inner.is_none() {
            return;
        }

        let max_alloc = (self.limits.decoding_buffer_size as u64)
            .saturating_add(self.limits.intermediate_buffer_size as u64);

        let max_intermediate_alloc = max_alloc.saturating_sub(info.total_bytes_buffer());
        let mut tiff_limits: tiff::decoder::Limits = Default::default();
        tiff_limits.decoding_buffer_size =
            usize::try_from(max_alloc - max_intermediate_alloc).unwrap_or(usize::MAX);
        tiff_limits.intermediate_buffer_size =
            usize::try_from(max_intermediate_alloc).unwrap_or(usize::MAX);
        tiff_limits.ifd_value_size = tiff_limits.intermediate_buffer_size;

        self.inner = Some(self.inner.take().unwrap().with_limits(tiff_limits));
    }

    /// Interleave planes in our `buffer` into `output`.
    fn interleave_planes(
        &mut self,
        info: ImageInfo,
        layout: tiff::decoder::BufferLayoutPreference,
        output: &mut [u8],
    ) -> ImageResult<()> {
        if info.original_color_type != info.color_type.into() {
            return Err(ImageError::Unsupported(
                UnsupportedError::from_format_and_kind(
                    ImageFormat::Tiff.into(),
                    UnsupportedErrorKind::GenericFeature(
                        "Planar TIFF with CMYK color type is not supported".to_string(),
                    ),
                ),
            ));
        }

        // This only works if we and `tiff` agree on the layout, including the color type, of
        // the sample matrix.
        //
        // TODO: triple buffer in the other case and fixup the planar layout independent of
        // sample type. Problem description follows:
        //
        // That will suck since we can't call `interleave_planes` with a `ColorType` argument,
        // Changing that parameter to `ExtendedColorType` is a can of worms, and exposing the
        // underlying generic function is an optimization killer (we may want to help LLVM
        // optimize this interleaving by SIMD). For LumaAlpha(1) colors we should do the bit
        // expansion at the same time as interleaving to avoid wasting the memory traversal but
        // expand-then-interleave is at least clear, albeit an extra buffer required. Meanwhile
        // for `Cmyk8`/`Cmyk16` our output is smaller than the tiff buffer (4 samples to 3, or
        // 5 to 4 if we had alpha) and not wanting multiple conversion function implementations
        // we should interleave-then-expand?
        //
        // The hard part of the solution will be managing complexity.
        let plane_stride = layout.plane_stride.map_or(0, |n| n.get());
        let bytes = self.buffer.as_buffer(0);

        let planes = bytes
            .as_bytes()
            .chunks_exact(plane_stride)
            .collect::<Vec<_>>();

        // Gracefully handle a mismatch of expectations. This should not occur in practice as we
        // check that all planes have been read (see note on `read_image_to_buffer` usage below).
        if planes.len() < usize::from(info.color_type.channel_count()) {
            return Err(ImageError::Decoding(DecodingError::new(
                ImageFormat::Tiff.into(),
                "Not enough planes read from TIFF image".to_string(),
            )));
        }

        utils::interleave_planes(
            output,
            info.color_type,
            &planes[..usize::from(info.color_type.channel_count())],
        );

        Ok(())
    }
}

impl ImageInfo {
    // The buffer can be larger for CMYK than the RGB output
    fn total_bytes_buffer(&self) -> u64 {
        let (width, height) = self.dimensions;
        let total_pixels = u64::from(width) * u64::from(height);

        let bytes_per_pixel = match self.original_color_type {
            ExtendedColorType::Cmyk8 => 4,
            ExtendedColorType::Cmyk16 => 8,
            _ => u64::from(self.color_type.bytes_per_pixel()),
        };

        total_pixels.saturating_mul(bytes_per_pixel)
    }
}

fn check_ycbcr_subsampling<R: BufRead + Seek>(decoder: &mut Decoder<R>) -> ImageResult<()> {
    let compression = decoder
        .find_tag(Tag::Compression)
        .map_err(ImageError::from_tiff_decode)?
        .and_then(|v| v.into_u16().ok());

    const COMPRESSION_MODERN_JPEG: u16 = 7;
    if compression == Some(COMPRESSION_MODERN_JPEG) {
        return Ok(());
    }

    let subsampling = decoder
        .find_tag(TAG_YCBCR_SUBSAMPLING)
        .map_err(ImageError::from_tiff_decode)?
        .map(|value| value.into_u16_vec())
        .transpose()
        .map_err(ImageError::from_tiff_decode)?;

    let subsampling = subsampling.as_deref().unwrap_or(&[2, 2]);

    if subsampling != [1, 1] {
        return Err(ImageError::Unsupported(
            UnsupportedError::from_format_and_kind(
                ImageFormat::Tiff.into(),
                UnsupportedErrorKind::GenericFeature(format!(
                "Subsampling {:?} is not supported. Only (1,1) is supported for non-JPEG YCbCr.",
                subsampling
            )),
            ),
        ));
    }

    Ok(())
}

fn read_ycbcr_coefficients<R: BufRead + Seek>(decoder: &mut Decoder<R>) -> ImageResult<[f32; 3]> {
    let value = decoder
        .find_tag(TAG_YCBCR_COEFFICIENTS)
        .map_err(ImageError::from_tiff_decode)?;

    const DEFAULT_YCBCR_COEFFICIENTS: [f32; 3] = [0.299, 0.587, 0.114];
    let Some(value) = value else {
        return Ok(DEFAULT_YCBCR_COEFFICIENTS);
    };

    let list = match value {
        Value::List(list) if list.len() == 3 => list,
        _ => {
            return Err(ImageError::Decoding(DecodingError::new(
                ImageFormat::Tiff.into(),
                "YCbCrCoefficients tag (529) must contain exactly 3 rational values".to_string(),
            )));
        }
    };

    let mut coefficients = [0.0f32; 3];
    for (i, value) in list.iter().enumerate() {
        match value {
            Value::Rational(num, denom) if *denom != 0 => {
                coefficients[i] = *num as f32 / *denom as f32
            }
            _ => {
                return Err(ImageError::Decoding(DecodingError::new(
                    ImageFormat::Tiff.into(),
                    "YCbCrCoefficients tag (529) contains an invalid rational value".to_string(),
                )));
            }
        }
    }

    Ok(coefficients)
}

impl ImageError {
    fn from_tiff_decode(err: tiff::TiffError) -> ImageError {
        match err {
            tiff::TiffError::IoError(err) => ImageError::IoError(err),
            err @ (tiff::TiffError::FormatError(_)
            | tiff::TiffError::IntSizeError
            | tiff::TiffError::UsageError(_)) => {
                ImageError::Decoding(DecodingError::new(ImageFormat::Tiff.into(), err))
            }
            tiff::TiffError::UnsupportedError(desc) => {
                ImageError::Unsupported(UnsupportedError::from_format_and_kind(
                    ImageFormat::Tiff.into(),
                    UnsupportedErrorKind::GenericFeature(desc.to_string()),
                ))
            }
            tiff::TiffError::LimitsExceeded => {
                ImageError::Limits(LimitError::from_kind(LimitErrorKind::InsufficientMemory))
            }
        }
    }

    fn from_tiff_encode(err: tiff::TiffError) -> ImageError {
        match err {
            tiff::TiffError::IoError(err) => ImageError::IoError(err),
            err @ (tiff::TiffError::FormatError(_)
            | tiff::TiffError::IntSizeError
            | tiff::TiffError::UsageError(_)) => {
                ImageError::Encoding(EncodingError::new(ImageFormat::Tiff.into(), err))
            }
            tiff::TiffError::UnsupportedError(desc) => {
                ImageError::Unsupported(UnsupportedError::from_format_and_kind(
                    ImageFormat::Tiff.into(),
                    UnsupportedErrorKind::GenericFeature(desc.to_string()),
                ))
            }
            tiff::TiffError::LimitsExceeded => {
                ImageError::Limits(LimitError::from_kind(LimitErrorKind::InsufficientMemory))
            }
        }
    }
}

impl<R: BufRead + Seek> ImageDecoder for TiffDecoder<R> {
    fn format_attributes(&self) -> FormatAttributes {
        FormatAttributes {
            // is any sort of iTXT chunk.
            xmp: DecodedMetadataHint::PerImage,
            icc: DecodedMetadataHint::PerImage,
            exif: DecodedMetadataHint::PerImage,
            // not provided above.
            iptc: DecodedMetadataHint::Unsupported,
            supports_sequence: true,
            ..FormatAttributes::default()
        }
    }

    fn prepare_image(&mut self) -> ImageResult<DecoderPreparedImage> {
        let info = self.peek_info()?;
        let (width, height) = info.dimensions;

        Ok(DecoderPreparedImage::new(width, height, info.color_type))
    }

    fn icc_profile(&mut self) -> ImageResult<Option<Vec<u8>>> {
        if let Some(decoder) = &mut self.inner {
            Ok(decoder.get_tag_u8_vec(Tag::IccProfile).ok())
        } else {
            Ok(None)
        }
    }

    fn xmp_metadata(&mut self) -> ImageResult<Option<Vec<u8>>> {
        let Some(decoder) = &mut self.inner else {
            return Ok(None);
        };

        let value = match decoder.get_tag(TAG_XML_PACKET) {
            Ok(value) => value,
            Err(tiff::TiffError::FormatError(tiff::TiffFormatError::RequiredTagNotFound(_))) => {
                return Ok(None);
            }
            Err(err) => return Err(ImageError::from_tiff_decode(err)),
        };
        value
            .into_u8_vec()
            .map(Some)
            .map_err(ImageError::from_tiff_decode)
    }

    fn set_limits(&mut self, limits: crate::Limits) -> ImageResult<()> {
        limits.check_support(&crate::LimitSupport::default())?;

        let reserved = match self.info {
            ImageState::At(info) => info,
            // Construct a dummy info that did not consume any memory.
            _ => ImageInfo {
                dimensions: (0, 0),
                color_type: ColorType::L8,
                original_color_type: ExtendedColorType::L8,
                ycbcr_coefficients: [0.0; 3],
            },
        };

        let (width, height) = reserved.dimensions;
        limits.check_dimensions(width, height)?;

        let max_alloc = limits
            .max_alloc
            .and_then(|n| usize::try_from(n).ok())
            .unwrap_or(usize::MAX);

        self.limits.decoding_buffer_size = max_alloc;
        self.limits.intermediate_buffer_size = 0;
        self.redistribute_limits();

        Ok(())
    }

    fn read_image(&mut self, buf: &mut [u8]) -> ImageResult<DecodedImageAttributes> {
        let info = self.peek_info()?;
        let layout = self.prepare_image()?;

        let original_color_type = Some(info.original_color_type);
        assert_eq!(u64::try_from(buf.len()), Ok(layout.total_bytes()));

        let Some(reader) = &mut self.inner else {
            return Err(ImageError::Parameter(ParameterError::from_kind(
                ParameterErrorKind::FailedAlready,
            )));
        };

        let layout = reader
            .read_image_to_buffer(&mut self.buffer)
            .map_err(ImageError::from_tiff_decode)?;

        // Check if we have all of the planes. Otherwise we ran into the allocation limit.
        if self.buffer.as_buffer(0).as_bytes().len() < layout.complete_len {
            return Err(ImageError::Limits(LimitError::from_kind(
                LimitErrorKind::InsufficientMemory,
            )));
        }

        if layout.planes > 1 {
            // Note that we do not support planar layouts if we have to do conversion. Yet. See a
            // more detailed comment in the implementation.
            self.interleave_planes(info, layout, buf)?;
            return Ok(DecodedImageAttributes::default());
        }

        match &self.buffer {
            DecodingResult::U8(v) if info.original_color_type == ExtendedColorType::Cmyk8 => {
                let buf = buf.as_chunks_mut::<3>().0;
                for (cmyk, rgb) in v.as_chunks::<4>().0.iter().zip(buf) {
                    *rgb = cmyk_to_rgb(cmyk);
                }
            }
            DecodingResult::U16(v) if info.original_color_type == ExtendedColorType::Cmyk16 => {
                let buf = buf.as_chunks_mut::<6>().0;
                for (cmyk, rgb) in v.as_chunks::<4>().0.iter().zip(buf) {
                    *rgb = bytemuck::cast(cmyk_to_rgb16(cmyk));
                }
            }
            DecodingResult::U8(v) if info.original_color_type == ExtendedColorType::L1 => {
                let width = info.dimensions.0;
                let row_bytes = width.div_ceil(8);

                for (in_row, out_row) in v
                    .chunks_exact(row_bytes as usize)
                    .zip(buf.chunks_exact_mut(width as usize))
                {
                    out_row.copy_from_slice(&utils::expand_bits(1, width, in_row));
                }
            }
            DecodingResult::U8(v) if info.original_color_type == ExtendedColorType::YCbCr8 => {
                let [lr, lg, lb] = info.ycbcr_coefficients;
                let ycbcr = v.as_chunks::<3>().0;
                let out = buf.as_chunks_mut::<3>().0;

                ycbcr_to_rgb8(ycbcr, lr, lg, lb, out);
            }
            DecodingResult::U8(v) => {
                buf.copy_from_slice(v);
            }
            DecodingResult::U16(v) => {
                buf.copy_from_slice(bytemuck::cast_slice(v));
            }
            DecodingResult::U32(v) => {
                buf.copy_from_slice(bytemuck::cast_slice(v));
            }
            DecodingResult::U64(v) => {
                buf.copy_from_slice(bytemuck::cast_slice(v));
            }
            DecodingResult::I8(v) => {
                buf.copy_from_slice(bytemuck::cast_slice(v));
            }
            DecodingResult::I16(v) => {
                buf.copy_from_slice(bytemuck::cast_slice(v));
            }
            DecodingResult::I32(v) => {
                buf.copy_from_slice(bytemuck::cast_slice(v));
            }
            DecodingResult::I64(v) => {
                buf.copy_from_slice(bytemuck::cast_slice(v));
            }
            DecodingResult::F32(v) => {
                buf.copy_from_slice(bytemuck::cast_slice(v));
            }
            DecodingResult::F64(v) => {
                buf.copy_from_slice(bytemuck::cast_slice(v));
            }
            DecodingResult::F16(_) => unreachable!(),
        }

        let orientation = reader
            .find_tag(Tag::Orientation)
            .map_err(ImageError::from_tiff_decode)?
            .and_then(|v| Orientation::from_exif(v.into_u16().ok()?.min(255) as u8));

        // Indicate to advance.
        self.info = ImageState::Consumed;

        Ok(DecodedImageAttributes {
            orientation,
            original_color_type,
            ..DecodedImageAttributes::default()
        })
    }

    fn exif_metadata(&mut self) -> ImageResult<Option<Vec<u8>>> {
        Ok(None)
    }

    fn iptc_metadata(&mut self) -> ImageResult<Option<Vec<u8>>> {
        Ok(None)
    }

    fn more_images(&self) -> crate::io::SequenceControl {
        self.inner
            .as_ref()
            .and_then(|reader| {
                reader
                    .more_images()
                    .then_some(crate::io::SequenceControl::MaybeMore)
            })
            .unwrap_or(crate::io::SequenceControl::None)
    }
}

/// Encoder for tiff images
pub struct TiffEncoder<W> {
    w: W,
    icc: Option<Vec<u8>>,
    xmp: Option<Vec<u8>>,
}

fn ycbcr_to_rgb8(ycbcr: &[[u8; 3]], lr: f32, lg: f32, lb: f32, out: &mut [[u8; 3]]) {
    let coeff_r = 2.0 * (1.0 - lr);
    let coeff_b = 2.0 * (1.0 - lb);
    let inv_lg = 1.0 / lg;

    for (src, dst) in ycbcr.iter().zip(out.iter_mut()) {
        let y = f32::from(src[0]);
        let cb = f32::from(src[1]) - 128.0;
        let cr = f32::from(src[2]) - 128.0;

        let r = y + cr * coeff_r;
        let b = y + cb * coeff_b;
        let g = (y - lr * r - lb * b) * inv_lg;

        dst[0] = (r + 0.5) as u8;
        dst[1] = (g + 0.5) as u8;
        dst[2] = (b + 0.5) as u8;
    }
}

fn cmyk_to_rgb(cmyk: &[u8; 4]) -> [u8; 3] {
    let c = cmyk[0] as u32;
    let m = cmyk[1] as u32;
    let y = cmyk[2] as u32;
    let k = cmyk[3] as u32;

    let k_inv = 255 - k;
    [
        (((255 - c) * k_inv) / 255) as u8,
        (((255 - m) * k_inv) / 255) as u8,
        (((255 - y) * k_inv) / 255) as u8,
    ]
}

fn cmyk_to_rgb16(cmyk: &[u16; 4]) -> [u16; 3] {
    let c = cmyk[0] as u64;
    let m = cmyk[1] as u64;
    let y = cmyk[2] as u64;
    let k = cmyk[3] as u64;

    let k_inv = 65535 - k;
    [
        (((65535 - c) * k_inv) / 65535) as u16,
        (((65535 - m) * k_inv) / 65535) as u16,
        (((65535 - y) * k_inv) / 65535) as u16,
    ]
}

/// Convert a slice of sample bytes to its semantic type, being a `Pod`.
fn u8_slice_as_pod<P: bytemuck::Pod>(buf: &[u8]) -> ImageResult<std::borrow::Cow<'_, [P]>> {
    bytemuck::try_cast_slice(buf)
        .map(std::borrow::Cow::Borrowed)
        .or_else(|err| {
            match err {
                bytemuck::PodCastError::TargetAlignmentGreaterAndInputNotAligned => {
                    // If the buffer is not aligned for a native slice, copy the buffer into a Vec,
                    // aligning it in the process. This is only done if the element count can be
                    // represented exactly.
                    let vec = bytemuck::allocation::pod_collect_to_vec(buf);
                    Ok(std::borrow::Cow::Owned(vec))
                }
                /* only expecting: bytemuck::PodCastError::OutputSliceWouldHaveSlop */
                _ => {
                    // `bytemuck::PodCastError` of bytemuck-1.2.0 does not implement `Error` and
                    // `Display` trait.
                    // See <https://github.com/Lokathor/bytemuck/issues/22>.
                    Err(ImageError::Parameter(ParameterError::from_kind(
                        ParameterErrorKind::Generic(format!(
                            "Casting samples to their representation failed: {err:?}",
                        )),
                    )))
                }
            }
        })
}

impl<W: Write + Seek> TiffEncoder<W> {
    /// Create a new encoder that writes its output to `w`
    pub fn new(w: W) -> TiffEncoder<W> {
        TiffEncoder {
            w,
            icc: None,
            xmp: None,
        }
    }

    /// Private wrapper function to encode the image with a generic color type. This is used to reduce code duplication in the public `write_image` function.
    fn write_tiff<C: tiff::encoder::colortype::ColorType<Inner: bytemuck::Pod>>(
        self,
        width: u32,
        height: u32,
        data: &[u8],
    ) -> ImageResult<()>
    where
        [C::Inner]: tiff::encoder::TiffValue,
    {
        let mut encoder =
            tiff::encoder::TiffEncoder::new(self.w).map_err(ImageError::from_tiff_encode)?;
        let data = u8_slice_as_pod::<C::Inner>(data)?;
        let mut img_encoder = encoder
            .new_image::<C>(width, height)
            .map_err(ImageError::from_tiff_encode)?;
        if self.icc.is_some() || self.xmp.is_some() {
            let ifd_encoder = img_encoder.encoder();
            if let Some(icc_profile) = self.icc {
                ifd_encoder
                    .write_tag(Tag::IccProfile, icc_profile.as_slice())
                    .map_err(ImageError::from_tiff_encode)?;
            }
            if let Some(xmp) = self.xmp {
                ifd_encoder
                    .write_tag(TAG_XML_PACKET, xmp.as_slice())
                    .map_err(ImageError::from_tiff_encode)?;
            }
        }
        img_encoder
            .write_data(&data)
            .map_err(ImageError::from_tiff_encode)
    }
}

impl<W: Write + Seek> ImageEncoder for TiffEncoder<W> {
    /// Encodes the image `image` that has dimensions `width` and `height` and `ColorType` `c`.
    ///
    /// 16-bit types assume the buffer is native endian.
    ///
    /// # Panics
    ///
    /// Panics if the buffer does not hold exactly the number of bytes required for the given
    /// `width`, `height`, and `color_type`, accounting for rows padded to whole bytes for
    /// sub-byte color types: `height * ((width * color_type.bits_per_pixel() as u32 + 7) / 8)`.
    #[track_caller]
    fn write_image(
        self,
        buf: &[u8],
        width: u32,
        height: u32,
        color_type: ExtendedColorType,
    ) -> ImageResult<()> {
        use tiff::encoder::colortype::{
            Gray16, Gray32Float, Gray8, RGB32Float, RGBA32Float, RGB16, RGB8, RGBA16, RGBA8,
        };
        let expected_buffer_len = color_type.buffer_size(width, height);
        assert_eq!(
            expected_buffer_len,
            buf.len() as u64,
            "Invalid buffer length: expected {expected_buffer_len} got {} for {width}x{height} image",
            buf.len(),
        );
        match color_type {
            ExtendedColorType::L8 => self.write_tiff::<Gray8>(width, height, buf),
            ExtendedColorType::Rgb8 => self.write_tiff::<RGB8>(width, height, buf),
            ExtendedColorType::Rgba8 => self.write_tiff::<RGBA8>(width, height, buf),
            ExtendedColorType::L16 => self.write_tiff::<Gray16>(width, height, buf),
            ExtendedColorType::Rgb16 => self.write_tiff::<RGB16>(width, height, buf),
            ExtendedColorType::Rgba16 => self.write_tiff::<RGBA16>(width, height, buf),
            ExtendedColorType::L32F => self.write_tiff::<Gray32Float>(width, height, buf),
            ExtendedColorType::Rgb32F => self.write_tiff::<RGB32Float>(width, height, buf),
            ExtendedColorType::Rgba32F => self.write_tiff::<RGBA32Float>(width, height, buf),
            _ => Err(ImageError::Unsupported(
                UnsupportedError::from_format_and_kind(
                    ImageFormat::Tiff.into(),
                    UnsupportedErrorKind::Color(color_type),
                ),
            )),
        }
    }

    fn set_icc_profile(&mut self, icc_profile: Vec<u8>) -> Result<(), UnsupportedError> {
        self.icc = Some(icc_profile);
        Ok(())
    }

    fn set_xmp_metadata(&mut self, xmp: Vec<u8>) -> Result<(), UnsupportedError> {
        self.xmp = Some(xmp);
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use std::io::Cursor;

    use crate::{
        EncodableLayout, ExtendedColorType, GenericImageView, ImageBuffer, ImageDecoder as _,
        ImageEncoder, ImageReader, Luma, Pixel, PixelWithColorType, Rgb, Rgba,
    };

    use super::{TiffDecoder, TiffEncoder};

    #[test]
    fn roundtrip_xmp() {
        let img = [255u8, 0, 0, 0, 255, 0, 0, 0, 255];
        let xmp = b"<x:xmpmeta xmlns:x=\"adobe:ns:meta/\"><rdf:RDF></rdf:RDF></x:xmpmeta>".to_vec();

        let mut encoded = Vec::new();
        {
            let mut encoder = TiffEncoder::new(Cursor::new(&mut encoded));
            encoder.set_xmp_metadata(xmp.clone()).unwrap();
            encoder
                .write_image(&img, 3, 1, ExtendedColorType::Rgb8)
                .expect("Could not encode image");
        }

        let mut decoder = TiffDecoder::new(Cursor::new(&encoded)).expect("Could not decode image");
        let decoded_xmp = decoder
            .xmp_metadata()
            .expect("Error decoding XMP")
            .expect("XMP is empty");
        assert_eq!(xmp, decoded_xmp);
    }

    #[test]
    fn roundtrip_color_types() {
        let img_l8 = ImageBuffer::from_fn(32, 32, |x, y| Luma([(x + y) as u8]));
        let img_rgb8 = ImageBuffer::from_fn(32, 32, |x, y| Rgb([x as u8, y as u8, (x + y) as u8]));
        let img_rgba8 = ImageBuffer::from_fn(32, 32, |x, y| {
            Rgba([x as u8, y as u8, (x + y) as u8, (x * y) as u8])
        });

        assert_roundtrip::<Luma<u8>>(&img_l8);
        assert_roundtrip::<Rgb<u8>>(&img_rgb8);
        assert_roundtrip::<Rgba<u8>>(&img_rgba8);

        assert_roundtrip::<Luma<u16>>(&img_l8.convert());
        assert_roundtrip::<Rgb<u16>>(&img_rgb8.convert());
        assert_roundtrip::<Rgba<u16>>(&img_rgba8.convert());

        assert_roundtrip::<Luma<f32>>(&img_l8.convert());
        assert_roundtrip::<Rgb<f32>>(&img_rgb8.convert());
        assert_roundtrip::<Rgba<f32>>(&img_rgba8.convert());

        fn assert_roundtrip<P: Pixel + PixelWithColorType>(img: &ImageBuffer<P, Vec<P::Subpixel>>)
        where
            [P::Subpixel]: EncodableLayout,
            Rgba<u8>: crate::color::FromColor<P>,
        {
            let mut encoded = Vec::new();
            let encoder = TiffEncoder::new(Cursor::new(&mut encoded));
            ImageBuffer::write_with_encoder(img, encoder).expect("Could not encoder image");

            let mut reader = ImageReader::new(Cursor::new(encoded)).unwrap();
            let (decoded, meta) = reader.decode().expect("Could not decode image");

            assert_eq!(img.dimensions(), decoded.dimensions());
            assert_eq!(Some(P::COLOR_TYPE), meta.attributes().original_color_type);

            let img_rgba8 = img.convert::<Rgba<u8>>();
            let decoded_rgba8 = decoded.to_rgba8();

            assert_eq!(img_rgba8, decoded_rgba8);
        }
    }
}

Coverage Report

Created: 2026-11-12 08:04