Struct png::Decoder

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pub struct Decoder<R: Read> { /* private fields */ }
Expand description

PNG Decoder

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impl<R: Read> Decoder<R>

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pub fn new(r: R) -> Decoder<R>

Create a new decoder configuration with default limits.

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pub fn new_with_limits(r: R, limits: Limits) -> Decoder<R>

Create a new decoder configuration with custom limits.

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pub fn new_with_options(r: R, decode_options: DecodeOptions) -> Decoder<R>

Create a new decoder configuration with custom DecodeOptions.

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pub fn set_limits(&mut self, limits: Limits)

Limit resource usage.

Note that your allocations, e.g. when reading into a pre-allocated buffer, are NOT considered part of the limits. Nevertheless, required intermediate buffers such as for singular lines is checked against the limit.

Note that this is a best-effort basis.

use std::fs::File;
use png::{Decoder, Limits};
// This image is 32×32, 1bit per pixel. The reader buffers one row which requires 4 bytes.
let mut limits = Limits::default();
limits.bytes = 3;
let mut decoder = Decoder::new_with_limits(File::open("tests/pngsuite/basi0g01.png").unwrap(), limits);
assert!(decoder.read_info().is_err());

// This image is 32x32 pixels, so the decoder will allocate less than 10Kib
let mut limits = Limits::default();
limits.bytes = 10*1024;
let mut decoder = Decoder::new_with_limits(File::open("tests/pngsuite/basi0g01.png").unwrap(), limits);
assert!(decoder.read_info().is_ok());
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pub fn read_header_info(&mut self) -> Result<&Info<'static>, DecodingError>

Read the PNG header and return the information contained within.

Most image metadata will not be read until read_info is called, so those fields will be None or empty.

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pub fn read_info(self) -> Result<Reader<R>, DecodingError>

Reads all meta data until the first IDAT chunk

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pub fn set_transformations(&mut self, transform: Transformations)

Set the allowed and performed transformations.

A transformation is a pre-processing on the raw image data modifying content or encoding. Many options have an impact on memory or CPU usage during decoding.

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

Set the decoder to ignore all text chunks while parsing.

eg.

use std::fs::File;
use png::Decoder;
let mut decoder = Decoder::new(File::open("tests/pngsuite/basi0g01.png").unwrap());
decoder.set_ignore_text_chunk(true);
assert!(decoder.read_info().is_ok());
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pub fn ignore_checksums(&mut self, ignore_checksums: bool)

Set the decoder to ignore and not verify the Adler-32 checksum and CRC code.

Auto Trait Implementations§

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impl<R> Freeze for Decoder<R>
where R: Freeze,

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impl<R> RefUnwindSafe for Decoder<R>
where R: RefUnwindSafe,

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impl<R> Send for Decoder<R>
where R: Send,

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impl<R> Sync for Decoder<R>
where R: Sync,

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impl<R> Unpin for Decoder<R>
where R: Unpin,

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impl<R> UnwindSafe for Decoder<R>
where R: UnwindSafe,

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.