Struct Ifd 

pub struct Ifd {
    pub entries: Vec<IfdEntry>,
    pub next_ifd_offset: u64,
    /* private fields */
}

A parsed Image File Directory (IFD).

An IFD contains metadata about one image in the TIFF file. WSI files typically have multiple IFDs: one for each pyramid level, plus label/macro images.

The entries are stored both as a vector (preserving order) and as a hashmap (for fast lookup by tag).

Fields

entries: Vec<IfdEntry>

All entries in this IFD, in file order

next_ifd_offset: u64

Offset to the next IFD (0 if this is the last IFD)

Implementations

impl Ifd

pub fn parse(bytes: &[u8], header: &TiffHeader) -> Result<Self, TiffError>

Parse an IFD from raw bytes.

The bytes should start at the IFD offset and contain:

• Entry count (2 or 8 bytes depending on format)
• All entries (12 or 20 bytes each)
• Next IFD offset (4 or 8 bytes)

Arguments

• bytes - Raw IFD bytes
• header - The TIFF header

Errors

Returns an error if the bytes are too short for the declared entry count.

pub fn calculate_size(entry_count: u64, header: &TiffHeader) -> usize

Calculate the total size in bytes needed to read this IFD.

This can be used to determine how many bytes to fetch before parsing. Note: This is the size of the IFD structure itself, not including any values stored at external offsets.

Arguments

• entry_count - Number of entries in the IFD
• header - The TIFF header

pub fn get_entry(&self, tag_id: u16) -> Option<&IfdEntry>

Get an entry by its tag ID.

pub fn get_entry_by_tag(&self, tag: TiffTag) -> Option<&IfdEntry>

Get an entry by its known TiffTag.

pub fn get_u32(&self, tag: TiffTag, byte_order: ByteOrder) -> Option<u32>

Get an inline u32 value for a tag.

This is a convenience method for reading simple scalar values like ImageWidth, ImageLength, TileWidth, etc.

pub fn get_u64(&self, tag: TiffTag, byte_order: ByteOrder) -> Option<u64>

Get an inline u64 value for a tag.

pub fn get_u16(&self, tag: TiffTag, byte_order: ByteOrder) -> Option<u16>

Get an inline u16 value for a tag.

pub fn is_tiled(&self) -> bool

Check if this IFD has tile organization (vs strip).

Returns true if TileWidth and TileLength tags are present.

pub fn is_stripped(&self) -> bool

Check if this IFD has strip organization.

Returns true if StripOffsets tag is present.

pub fn image_width(&self, byte_order: ByteOrder) -> Option<u32>

Get image width from this IFD.

pub fn image_height(&self, byte_order: ByteOrder) -> Option<u32>

Get image height (length) from this IFD.

pub fn tile_width(&self, byte_order: ByteOrder) -> Option<u32>

Get tile width from this IFD.

pub fn tile_height(&self, byte_order: ByteOrder) -> Option<u32>

Get tile height (length) from this IFD.

pub fn compression(&self, byte_order: ByteOrder) -> Option<u16>

Get compression scheme from this IFD.

pub fn entry_count(&self) -> usize

Get the number of entries in this IFD.

Trait Implementations

impl Clone for Ifd

fn clone(&self) -> Ifd

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Ifd

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.