Struct exr::meta::header::Header

pub struct Header {
    pub channels: ChannelList,
    pub compression: Compression,
    pub blocks: BlockDescription,
    pub line_order: LineOrder,
    pub layer_size: Vec2<usize>,
    pub deep: bool,
    pub deep_data_version: Option<i32>,
    pub chunk_count: usize,
    pub max_samples_per_pixel: Option<usize>,
    pub shared_attributes: ImageAttributes,
    pub own_attributes: LayerAttributes,
}

Describes a single layer in a file. A file can have any number of layers. The meta data contains one header per layer.

Fields

channels: ChannelList

List of channels in this layer.

compression: Compression

How the pixel data of all channels in this layer is compressed. May be Compression::Uncompressed.

blocks: BlockDescription

Describes how the pixels of this layer are divided into smaller blocks. A single block can be loaded without processing all bytes of a file.

Also describes whether a file contains multiple resolution levels: mip maps or rip maps. This allows loading not the full resolution, but the smallest sensible resolution.

line_order: LineOrder

In what order the tiles of this header occur in the file.

layer_size: Vec2<usize>

The resolution of this layer. Equivalent to the size of the DataWindow.

deep: bool

Whether this layer contains deep data.

deep_data_version: Option<i32>

This library supports only deep data version 1.

chunk_count: usize

Number of chunks, that is, scan line blocks or tiles, that this image has been divided into. This number is calculated once at the beginning of the read process or when creating a header object.

This value includes all chunks of all resolution levels.

Warning This value is relied upon. You should probably use Header::with_encoding, which automatically updates the chunk count.

max_samples_per_pixel: Option<usize>

Maximum number of samples in a single pixel in a deep image.

shared_attributes: ImageAttributes

Includes mandatory fields like pixel aspect or display window which must be the same for all layers.

own_attributes: LayerAttributes

Does not include the attributes required for reading the file contents. Excludes standard fields that must be the same for all headers.

Implementations

impl Header

pub fn new( name: Text, data_size: impl Into<Vec2<usize>>, channels: SmallVec<[ChannelDescription; 5]>, ) -> Self

Create a new Header with the specified name, display window and channels. Use Header::with_encoding and the similar methods to add further properties to the header.

The other settings are left to their default values:

• RLE compression
• display window equal to data window
• tiles (64 x 64 px)
• unspecified line order
• no custom attributes

pub fn with_display_window(self, display_window: IntegerBounds) -> Self

Set the display window, that is, the global clipping rectangle. Must be the same for all headers of a file.

pub fn with_position(self, position: Vec2<i32>) -> Self

Set the offset of this layer.

pub fn with_encoding( self, compression: Compression, blocks: BlockDescription, line_order: LineOrder, ) -> Self

Set compression, tiling, and line order. Automatically computes chunk count.

pub fn with_attributes(self, own_attributes: LayerAttributes) -> Self

Set all attributes of the header that are not shared with all other headers in the image.

pub fn with_shared_attributes(self, shared_attributes: ImageAttributes) -> Self

Set all attributes of the header that are shared with all other headers in the image.

pub fn enumerate_ordered_blocks( &self, ) -> impl Iterator<Item = (usize, TileIndices)> + Send

Iterate over all blocks, in the order specified by the headers line order attribute. Unspecified line order is treated as increasing line order. Also enumerates the index of each block in the header, as if it were sorted in increasing line order.

pub fn blocks_increasing_y_order( &self, ) -> impl Iterator<Item = TileIndices> + ExactSizeIterator + DoubleEndedIterator

Iterate over all tile indices in this header in LineOrder::Increasing order.

pub fn max_block_pixel_size(&self) -> Vec2<usize>

The default pixel resolution of a single block (tile or scan line block). Not all blocks have this size, because they may be cutoff at the end of the image.

pub fn get_block_data_window_pixel_coordinates( &self, tile: TileCoordinates, ) -> Result<IntegerBounds>

Calculate the position of a block in the global infinite 2D space of a file. May be negative.

pub fn get_absolute_block_pixel_coordinates( &self, tile: TileCoordinates, ) -> Result<IntegerBounds>

Calculate the pixel index rectangle inside this header. Is not negative. Starts at 0.

pub fn get_block_data_indices( &self, block: &CompressedBlock, ) -> Result<TileCoordinates>

Return the tile index, converting scan line block coordinates to tile indices. Starts at 0 and is not negative.

pub fn get_scan_line_block_tile_coordinates( &self, block_y_coordinate: i32, ) -> Result<TileCoordinates>

Computes the absolute tile coordinate data indices, which start at 0.

pub fn max_block_byte_size(&self) -> usize

Maximum byte length of an uncompressed or compressed block, used for validation.

pub fn total_pixel_bytes(&self) -> usize

Returns the number of bytes that the pixels of this header will require when stored without compression. Respects multi-resolution levels and subsampling.

pub fn max_pixel_file_bytes(&self) -> usize

Approximates the maximum number of bytes that the pixels of this header will consume in a file. Due to compression, the actual byte size may be smaller.

pub fn validate( &self, is_multilayer: bool, long_names: &mut bool, strict: bool, ) -> UnitResult

Validate this instance.

pub fn read_all( read: &mut PeekRead<impl Read>, version: &Requirements, pedantic: bool, ) -> Result<Headers>

Read the headers without validating them.

pub fn write_all( headers: &[Header], write: &mut impl Write, is_multilayer: bool, ) -> UnitResult

Without validation, write the headers to the byte stream.

pub fn all_named_attributes( &self, ) -> impl '_ + Iterator<Item = (&TextSlice, AttributeValue)>

Iterate over all (name, attribute_value) pairs in this header that would be written to a file. The order of attributes is arbitrary and may change in future versions. Will always contain all strictly required attributes, such as channels, compression, data window, and similar. Hint: Use attribute.kind_name() to obtain the standardized name of the attribute type. Does not validate the header or attributes.

pub fn read( read: &mut PeekRead<impl Read>, requirements: &Requirements, pedantic: bool, ) -> Result<Self>

Read the value without validating.

pub fn write(&self, write: &mut impl Write) -> UnitResult

Without validation, write this instance to the byte stream.

pub fn data_window(&self) -> IntegerBounds

The rectangle describing the bounding box of this layer within the infinite global 2D space of the file.

Trait Implementations

impl Clone for Header

fn clone(&self) -> Header

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Header

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

Formats the value using the given formatter.

impl PartialEq for Header

fn eq(&self, other: &Header) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for Header