Struct png::decoder::stream::StreamingDecoder

pub struct StreamingDecoder {
    state: Option<State>,
    current_chunk: ChunkState,
    inflater: ZlibStream,
    pub(crate) info: Option<Info<'static>>,
    current_seq_no: Option<u32>,
    have_idat: bool,
    ready_for_idat_chunks: bool,
    ready_for_fdat_chunks: bool,
    have_iccp: bool,
    decode_options: DecodeOptions,
    pub(crate) limits: Limits,
}

PNG StreamingDecoder (low-level interface)

By default, the decoder does not verify Adler-32 checksum computation. To enable checksum verification, set it with StreamingDecoder::set_ignore_adler32 before starting decompression.

Fields

state: Option<State>

current_chunk: ChunkState

inflater: ZlibStream

The inflater state handling consecutive IDAT and fdAT chunks.

info: Option<Info<'static>>

The complete image info read from all prior chunks.

current_seq_no: Option<u32>

The animation chunk sequence number.

have_idat: bool

Whether we have already seen a start of an IDAT chunk. (Used to validate chunk ordering - some chunk types can only appear before or after an IDAT chunk.)

ready_for_idat_chunks: bool

Whether we are ready for a start of an IDAT chunk sequence. Initially true and set to false when the first sequence of consecutive IDAT chunks ends.

ready_for_fdat_chunks: bool

Whether we are ready for a start of an fdAT chunk sequence. Initially false. Set to true after encountering an fcTL chunk. Set to false when a sequence of consecutive fdAT chunks ends.

have_iccp: bool

Whether we have already seen an iCCP chunk. Used to prevent parsing of duplicate iCCP chunks.

decode_options: DecodeOptions

limits: Limits

Implementations

impl StreamingDecoder

pub fn new() -> StreamingDecoder

Creates a new StreamingDecoder

Allocates the internal buffers.

pub fn new_with_options(decode_options: DecodeOptions) -> StreamingDecoder

pub fn reset(&mut self)

Resets the StreamingDecoder

pub fn info(&self) -> Option<&Info<'static>>

Provides access to the inner info field

pub fn set_ignore_text_chunk(&mut self, ignore_text_chunk: bool)

pub fn set_ignore_iccp_chunk(&mut self, ignore_iccp_chunk: bool)

pub fn ignore_adler32(&self) -> bool

Return whether the decoder is set to ignore the Adler-32 checksum.

pub fn set_ignore_adler32(&mut self, ignore_adler32: bool) -> bool

Set whether to compute and verify the Adler-32 checksum during decompression. Return true if the flag was successfully set.

The decoder defaults to true.

This flag cannot be modified after decompression has started until the StreamingDecoder is reset.

pub fn set_ignore_crc(&mut self, ignore_crc: bool)

Set whether to compute and verify the Adler-32 checksum during decompression.

The decoder defaults to false.

pub fn set_skip_ancillary_crc_failures( &mut self, skip_ancillary_crc_failures: bool, )

Ignore ancillary chunks if CRC fails

Defaults to true

pub fn update( &mut self, buf: &[u8], image_data: &mut Vec<u8>, ) -> Result<(usize, Decoded), DecodingError>

Low level StreamingDecoder interface.

Allows to stream partial data to the encoder. Returns a tuple containing the bytes that have been consumed from the input buffer and the current decoding result. If the decoded chunk was an image data chunk, it also appends the read data to image_data.

fn next_state( &mut self, buf: &[u8], image_data: &mut Vec<u8>, ) -> Result<(usize, Decoded), DecodingError>

fn parse_u32( &mut self, kind: U32ValueKind, u32_be_bytes: &[u8], image_data: &mut Vec<u8>, ) -> Result<Decoded, DecodingError>

fn reserve_current_chunk(&mut self) -> Result<(), DecodingError>

fn parse_chunk(&mut self, type_str: ChunkType) -> Result<Decoded, DecodingError>

fn parse_fctl(&mut self) -> Result<Decoded, DecodingError>

fn parse_actl(&mut self) -> Result<Decoded, DecodingError>

fn parse_plte(&mut self) -> Result<Decoded, DecodingError>

fn parse_trns(&mut self) -> Result<Decoded, DecodingError>

fn parse_phys(&mut self) -> Result<Decoded, DecodingError>

fn parse_chrm(&mut self) -> Result<Decoded, DecodingError>

fn parse_gama(&mut self) -> Result<Decoded, DecodingError>

fn parse_srgb(&mut self) -> Result<Decoded, DecodingError>

fn parse_iccp(&mut self) -> Result<Decoded, DecodingError>

fn parse_iccp_raw(&mut self) -> Result<(), DecodingError>

fn parse_ihdr(&mut self) -> Result<Decoded, DecodingError>

fn split_keyword(buf: &[u8]) -> Result<(&[u8], &[u8]), DecodingError>

fn parse_text(&mut self) -> Result<Decoded, DecodingError>

fn parse_ztxt(&mut self) -> Result<Decoded, DecodingError>

fn parse_itxt(&mut self) -> Result<Decoded, DecodingError>

Trait Implementations

impl Default for StreamingDecoder

fn default() -> Self

Returns the “default value” for a type.