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-use std::fs::File;
-use std::io::{self, BufRead, BufReader, Cursor, Read, Seek, SeekFrom};
-use std::path::Path;
-
-use crate::dynimage::DynamicImage;
-use crate::error::{ImageFormatHint, UnsupportedError, UnsupportedErrorKind};
-use crate::image::ImageFormat;
-use crate::{ImageError, ImageResult};
-
-use super::free_functions;
-
-/// 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.
-///
-/// ```
-/// # 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));
-///
-/// # #[cfg(feature = "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
-pub struct Reader<R: Read> {
- /// The reader. Should be buffered.
- inner: R,
- /// The format, if one has been set or deduced.
- format: Option<ImageFormat>,
- /// Decoding limits
- limits: super::Limits,
-}
-
-impl<R: Read> Reader<R> {
- /// Create a new image reader without a preset format.
- ///
- /// Assumes the reader is already buffered. For optimal performance,
- /// consider wrapping the reader with a `BufReader::new()`.
- ///
- /// 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
- pub fn new(buffered_reader: R) -> Self {
- Reader {
- inner: buffered_reader,
- format: None,
- limits: super::Limits::default(),
- }
- }
-
- /// Construct a reader with specified format.
- ///
- /// Assumes the reader is already buffered. For optimal performance,
- /// consider wrapping the reader with a `BufReader::new()`.
- pub fn with_format(buffered_reader: R, format: ImageFormat) -> Self {
- Reader {
- inner: buffered_reader,
- format: Some(format),
- limits: super::Limits::default(),
- }
- }
-
- /// Get the currently determined format.
- pub fn format(&self) -> Option<ImageFormat> {
- self.format
- }
-
- /// Supply the format as which to interpret the read image.
- pub fn set_format(&mut self, format: ImageFormat) {
- self.format = Some(format);
- }
-
- /// 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.
- pub fn clear_format(&mut self) {
- self.format = None;
- }
-
- /// Disable all decoding limits.
- pub fn no_limits(&mut self) {
- self.limits = super::Limits::no_limits();
- }
-
- /// Set a custom set of decoding limits.
- pub fn limits(&mut self, limits: super::Limits) {
- self.limits = limits;
- }
-
- /// Unwrap the reader.
- pub fn into_inner(self) -> R {
- self.inner
- }
-}
-
-impl Reader<BufReader<File>> {
- /// 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
- pub fn open<P>(path: P) -> io::Result<Self>
- where
- P: AsRef<Path>,
- {
- Self::open_impl(path.as_ref())
- }
-
- fn open_impl(path: &Path) -> io::Result<Self> {
- Ok(Reader {
- inner: BufReader::new(File::open(path)?),
- format: ImageFormat::from_path(path).ok(),
- limits: super::Limits::default(),
- })
- }
-}
-
-impl<R: BufRead + Seek> Reader<R> {
- /// 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(()) }
- /// ```
- pub fn with_guessed_format(mut self) -> io::Result<Self> {
- let format = self.guess_format()?;
- // Replace format if found, keep current state if not.
- self.format = format.or(self.format);
- Ok(self)
- }
-
- fn guess_format(&mut self) -> io::Result<Option<ImageFormat>> {
- let mut start = [0; 16];
-
- // Save current offset, read start, restore offset.
- let cur = self.inner.stream_position()?;
- let len = io::copy(
- // Accept shorter files but read at most 16 bytes.
- &mut self.inner.by_ref().take(16),
- &mut Cursor::new(&mut start[..]),
- )?;
- self.inner.seek(SeekFrom::Start(cur))?;
-
- Ok(free_functions::guess_format_impl(&start[..len as usize]))
- }
-
- /// 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`.
- pub fn into_dimensions(mut self) -> ImageResult<(u32, u32)> {
- let format = self.require_format()?;
- free_functions::image_dimensions_with_format_impl(self.inner, format)
- }
-
- /// 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`.
- pub fn decode(mut self) -> ImageResult<DynamicImage> {
- let format = self.require_format()?;
- free_functions::load_inner(self.inner, self.limits, format)
- }
-
- fn require_format(&mut self) -> ImageResult<ImageFormat> {
- self.format.ok_or_else(|| {
- ImageError::Unsupported(UnsupportedError::from_format_and_kind(
- ImageFormatHint::Unknown,
- UnsupportedErrorKind::Format(ImageFormatHint::Unknown),
- ))
- })
- }
-}
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