jpeg_decoder/
error.rs

1use alloc::boxed::Box;
2use alloc::fmt;
3use alloc::string::String;
4use core::result;
5use std::error::Error as StdError;
6use std::io::Error as IoError;
7
8use crate::ColorTransform;
9
10pub type Result<T> = result::Result<T, Error>;
11
12/// An enumeration over JPEG features (currently) unsupported by this library.
13///
14/// Support for features listed here may be included in future versions of this library.
15#[derive(Debug, Clone, PartialEq, Eq, Hash)]
16pub enum UnsupportedFeature {
17    /// Hierarchical JPEG.
18    Hierarchical,
19    /// JPEG using arithmetic entropy coding instead of Huffman coding.
20    ArithmeticEntropyCoding,
21    /// Sample precision in bits. 8 bit sample precision is what is currently supported in non-lossless coding process.
22    SamplePrecision(u8),
23    /// Number of components in an image. 1, 3 and 4 components are currently supported.
24    ComponentCount(u8),
25    /// An image can specify a zero height in the frame header and use the DNL (Define Number of
26    /// Lines) marker at the end of the first scan to define the number of lines in the frame.
27    DNL,
28    /// Subsampling ratio.
29    SubsamplingRatio,
30    /// A subsampling ratio not representable as an integer.
31    NonIntegerSubsamplingRatio,
32    /// Colour transform
33    ColorTransform(ColorTransform),
34}
35
36/// Errors that can occur while decoding a JPEG image.
37#[derive(Debug)]
38pub enum Error {
39    /// The image is not formatted properly. The string contains detailed information about the
40    /// error.
41    Format(String),
42    /// The image makes use of a JPEG feature not (currently) supported by this library.
43    Unsupported(UnsupportedFeature),
44    /// An I/O error occurred while decoding the image.
45    Io(IoError),
46    /// An internal error occurred while decoding the image.
47    Internal(Box<dyn StdError + Send + Sync + 'static>), //TODO: not used, can be removed with the next version bump
48}
49
50impl fmt::Display for Error {
51    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
52        match *self {
53            Error::Format(ref desc) => write!(f, "invalid JPEG format: {}", desc),
54            Error::Unsupported(ref feat) => write!(f, "unsupported JPEG feature: {:?}", feat),
55            Error::Io(ref err) => err.fmt(f),
56            Error::Internal(ref err) => err.fmt(f),
57        }
58    }
59}
60
61impl StdError for Error {
62    fn source(&self) -> Option<&(dyn StdError + 'static)> {
63        match *self {
64            Error::Io(ref err) => Some(err),
65            Error::Internal(ref err) => Some(&**err),
66            _ => None,
67        }
68    }
69}
70
71impl From<IoError> for Error {
72    fn from(err: IoError) -> Error {
73        Error::Io(err)
74    }
75}
jpeg_decoder/error.rs

jpeg_decoder/
error.rs
