| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/git/checkouts/incubator-teaclave-crates-c8106113f74feefc/ede1f68/image/./src/io/reader.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>reader.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../image/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../image/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="attribute">#[cfg(not(target_vendor = <span class="string">"teaclave"</span>))] |
| </span><span class="kw">use </span>std::fs::{File, OpenOptions}; |
| <span class="attribute">#[cfg(target_vendor = <span class="string">"teaclave"</span>)] |
| </span><span class="kw">use </span>std::untrusted::fs::{File, OpenOptions}; |
| <span class="kw">use </span>std::io::{<span class="self">self</span>, BufRead, BufReader, Cursor, Read, Seek, SeekFrom}; |
| <span class="kw">use </span>std::path::Path; |
| |
| <span class="kw">use </span><span class="kw">crate</span>::dynimage::DynamicImage; |
| <span class="kw">use </span><span class="kw">crate</span>::image::ImageFormat; |
| <span class="kw">use </span><span class="kw">crate</span>::error::{ImageFormatHint, UnsupportedError, UnsupportedErrorKind}; |
| <span class="kw">use crate</span>::{ImageError, ImageResult}; |
| |
| <span class="kw">use </span><span class="kw">super</span>::free_functions; |
| |
| <span class="doccomment">/// A multi-format image reader. |
| /// |
| /// Wraps an input reader to facilitate automatic detection of an image's format, appropriate |
| /// decoding method, and dispatches into the set of supported [`ImageDecoder`] implementations. |
| /// |
| /// ## Usage |
| /// |
| /// Opening a file, deducing the format based on the file path automatically, and trying to decode |
| /// the image contained can be performed by constructing the reader and immediately consuming it. |
| /// |
| /// ```no_run |
| /// # use image::ImageError; |
| /// # use image::io::Reader; |
| /// # fn main() -> Result<(), ImageError> { |
| /// let image = Reader::open("path/to/image.png")? |
| /// .decode()?; |
| /// # Ok(()) } |
| /// ``` |
| /// |
| /// It is also possible to make a guess based on the content. This is especially handy if the |
| /// source is some blob in memory and you have constructed the reader in another way. Here is an |
| /// example with a `pnm` black-and-white subformat that encodes its pixel matrix with ascii values. |
| /// |
| </span><span class="attribute">#[cfg_attr(feature = <span class="string">"pnm"</span>, doc = <span class="string">"```"</span>)] |
| #[cfg_attr(not(feature = <span class="string">"pnm"</span>), doc = <span class="string">"```no_run"</span>)] |
| </span><span class="doccomment">/// # use image::ImageError; |
| /// # use image::io::Reader; |
| /// # fn main() -> Result<(), ImageError> { |
| /// use std::io::Cursor; |
| /// use image::ImageFormat; |
| /// |
| /// let raw_data = b"P1 2 2\n\ |
| /// 0 1\n\ |
| /// 1 0\n"; |
| /// |
| /// let mut reader = Reader::new(Cursor::new(raw_data)) |
| /// .with_guessed_format() |
| /// .expect("Cursor io never fails"); |
| /// assert_eq!(reader.format(), Some(ImageFormat::Pnm)); |
| /// |
| /// let image = reader.decode()?; |
| /// # Ok(()) } |
| /// ``` |
| /// |
| /// As a final fallback or if only a specific format must be used, the reader always allows manual |
| /// specification of the supposed image format with [`set_format`]. |
| /// |
| /// [`set_format`]: #method.set_format |
| /// [`ImageDecoder`]: ../trait.ImageDecoder.html |
| </span><span class="kw">pub struct </span>Reader<R: Read> { |
| <span class="doccomment">/// The reader. |
| </span>inner: R, |
| <span class="doccomment">/// The format, if one has been set or deduced. |
| </span>format: <span class="prelude-ty">Option</span><ImageFormat>, |
| } |
| |
| <span class="kw">impl</span><R: Read> Reader<R> { |
| <span class="doccomment">/// Create a new image reader without a preset format. |
| /// |
| /// It is possible to guess the format based on the content of the read object with |
| /// [`with_guessed_format`], or to set the format directly with [`set_format`]. |
| /// |
| /// [`with_guessed_format`]: #method.with_guessed_format |
| /// [`set_format`]: method.set_format |
| </span><span class="kw">pub fn </span>new(reader: R) -> <span class="self">Self </span>{ |
| Reader { |
| inner: reader, |
| format: <span class="prelude-val">None</span>, |
| } |
| } |
| |
| <span class="doccomment">/// Construct a reader with specified format. |
| </span><span class="kw">pub fn </span>with_format(reader: R, format: ImageFormat) -> <span class="self">Self </span>{ |
| Reader { |
| inner: reader, |
| format: <span class="prelude-val">Some</span>(format), |
| } |
| } |
| |
| <span class="doccomment">/// Get the currently determined format. |
| </span><span class="kw">pub fn </span>format(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><ImageFormat> { |
| <span class="self">self</span>.format |
| } |
| |
| <span class="doccomment">/// Supply the format as which to interpret the read image. |
| </span><span class="kw">pub fn </span>set_format(<span class="kw-2">&mut </span><span class="self">self</span>, format: ImageFormat) { |
| <span class="self">self</span>.format = <span class="prelude-val">Some</span>(format); |
| } |
| |
| <span class="doccomment">/// Remove the current information on the image format. |
| /// |
| /// Note that many operations require format information to be present and will return e.g. an |
| /// `ImageError::Unsupported` when the image format has not been set. |
| </span><span class="kw">pub fn </span>clear_format(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="self">self</span>.format = <span class="prelude-val">None</span>; |
| } |
| |
| <span class="doccomment">/// Unwrap the reader. |
| </span><span class="kw">pub fn </span>into_inner(<span class="self">self</span>) -> R { |
| <span class="self">self</span>.inner |
| } |
| } |
| |
| <span class="kw">impl </span>Reader<BufReader<File>> { |
| <span class="doccomment">/// Open a file to read, format will be guessed from path. |
| /// |
| /// This will not attempt any io operation on the opened file. |
| /// |
| /// If you want to inspect the content for a better guess on the format, which does not depend |
| /// on file extensions, follow this call with a call to [`with_guessed_format`]. |
| /// |
| /// [`with_guessed_format`]: #method.with_guessed_format |
| </span><span class="kw">pub fn </span>open<P>(path: P) -> io::Result<<span class="self">Self</span>> <span class="kw">where </span>P: AsRef<Path> { |
| <span class="self">Self</span>::open_impl(path.as_ref()) |
| } |
| |
| <span class="kw">fn </span>open_impl(path: <span class="kw-2">&</span>Path) -> io::Result<<span class="self">Self</span>> { |
| <span class="kw">let </span>file = File::open(path)<span class="question-mark">?</span>; |
| <span class="prelude-val">Ok</span>(Reader { |
| inner: BufReader::new(file), |
| format: ImageFormat::from_path(path).ok(), |
| }) |
| } |
| } |
| |
| <span class="kw">impl</span><R: BufRead + Seek> Reader<R> { |
| <span class="doccomment">/// Make a format guess based on the content, replacing it on success. |
| /// |
| /// Returns `Ok` with the guess if no io error occurs. Additionally, replaces the current |
| /// format if the guess was successful. If the guess was unable to determine a format then |
| /// the current format of the reader is unchanged. |
| /// |
| /// Returns an error if the underlying reader fails. The format is unchanged. The error is a |
| /// `std::io::Error` and not `ImageError` since the only error case is an error when the |
| /// underlying reader seeks. |
| /// |
| /// When an error occurs, the reader may not have been properly reset and it is potentially |
| /// hazardous to continue with more io. |
| /// |
| /// ## Usage |
| /// |
| /// This supplements the path based type deduction from [`open`](Reader::open) with content based deduction. |
| /// This is more common in Linux and UNIX operating systems and also helpful if the path can |
| /// not be directly controlled. |
| /// |
| /// ```no_run |
| /// # use image::ImageError; |
| /// # use image::io::Reader; |
| /// # fn main() -> Result<(), ImageError> { |
| /// let image = Reader::open("image.unknown")? |
| /// .with_guessed_format()? |
| /// .decode()?; |
| /// # Ok(()) } |
| /// ``` |
| </span><span class="kw">pub fn </span>with_guessed_format(<span class="kw-2">mut </span><span class="self">self</span>) -> io::Result<<span class="self">Self</span>> { |
| <span class="kw">let </span>format = <span class="self">self</span>.guess_format()<span class="question-mark">?</span>; |
| <span class="comment">// Replace format if found, keep current state if not. |
| </span><span class="self">self</span>.format = format.or(<span class="self">self</span>.format); |
| <span class="prelude-val">Ok</span>(<span class="self">self</span>) |
| } |
| |
| <span class="kw">fn </span>guess_format(<span class="kw-2">&mut </span><span class="self">self</span>) -> io::Result<<span class="prelude-ty">Option</span><ImageFormat>> { |
| <span class="kw">let </span><span class="kw-2">mut </span>start = [<span class="number">0</span>; <span class="number">16</span>]; |
| |
| <span class="comment">// Save current offset, read start, restore offset. |
| </span><span class="kw">let </span>cur = <span class="self">self</span>.inner.seek(SeekFrom::Current(<span class="number">0</span>))<span class="question-mark">?</span>; |
| <span class="kw">let </span>len = io::copy( |
| <span class="comment">// Accept shorter files but read at most 16 bytes. |
| </span><span class="kw-2">&mut </span><span class="self">self</span>.inner.by_ref().take(<span class="number">16</span>), |
| <span class="kw-2">&mut </span>Cursor::new(<span class="kw-2">&mut </span>start[..]))<span class="question-mark">?</span>; |
| <span class="self">self</span>.inner.seek(SeekFrom::Start(cur))<span class="question-mark">?</span>; |
| |
| <span class="prelude-val">Ok</span>(free_functions::guess_format_impl(<span class="kw-2">&</span>start[..len <span class="kw">as </span>usize])) |
| } |
| |
| <span class="doccomment">/// Read the image dimensions. |
| /// |
| /// Uses the current format to construct the correct reader for the format. |
| /// |
| /// If no format was determined, returns an `ImageError::Unsupported`. |
| </span><span class="kw">pub fn </span>into_dimensions(<span class="kw-2">mut </span><span class="self">self</span>) -> ImageResult<(u32, u32)> { |
| <span class="kw">let </span>format = <span class="self">self</span>.require_format()<span class="question-mark">?</span>; |
| free_functions::image_dimensions_with_format_impl(<span class="self">self</span>.inner, format) |
| } |
| |
| <span class="doccomment">/// Read the image (replaces `load`). |
| /// |
| /// Uses the current format to construct the correct reader for the format. |
| /// |
| /// If no format was determined, returns an `ImageError::Unsupported`. |
| </span><span class="kw">pub fn </span>decode(<span class="kw-2">mut </span><span class="self">self</span>) -> ImageResult<DynamicImage> { |
| <span class="kw">let </span>format = <span class="self">self</span>.require_format()<span class="question-mark">?</span>; |
| free_functions::load(<span class="self">self</span>.inner, format) |
| } |
| |
| <span class="kw">fn </span>require_format(<span class="kw-2">&mut </span><span class="self">self</span>) -> ImageResult<ImageFormat> { |
| <span class="self">self</span>.format.ok_or_else(|| |
| ImageError::Unsupported(UnsupportedError::from_format_and_kind( |
| ImageFormatHint::Unknown, |
| UnsupportedErrorKind::Format(ImageFormatHint::Unknown)))) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="image" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
