Struct Reader

pub struct Reader { /* private fields */ }

A struct to parse the Exif attributes and create an Exif instance that holds the results.

Examples

use exif::{In, Reader, Tag};
let file = std::fs::File::open("tests/exif.jpg")?;
let exif = Reader::new()
    .read_from_container(&mut std::io::BufReader::new(&file))?;
let xres = exif.get_field(Tag::XResolution, In::PRIMARY)
    .ok_or(Error("tests/exif.jpg must have XResolution"))?;
assert_eq!(xres.display_value().with_unit(&exif).to_string(),
           "72 pixels per inch");

Implementations

impl Reader

pub fn new() -> Self

Constructs a new Reader.

Examples found in repository

examples/dumpexif.rs (line 50)

fn dump_file(path: &Path) -> Result<(), exif::Error> {
    let file = File::open(path)?;

    // To parse strictly:
    // let exif = exif::Reader::new()
    //     .read_from_container(&mut BufReader::new(&file))?;

    // To parse with continue-on-error mode:
    let exif = exif::Reader::new()
        .continue_on_error(true)
        .read_from_container(&mut BufReader::new(&file))
        .or_else(|e| e.distill_partial_result(|errors| {
            eprintln!("{}: {} warning(s)", path.display(), errors.len());
            errors.iter().for_each(|e| eprintln!("  {}", e));
        }))?;

    println!("{}", path.display());
    for f in exif.fields() {
        println!("  {}/{}: {}",
                 f.ifd_num.index(), f.tag,
                 f.display_value().with_unit(&exif));
        println!("      {:?}", f.value);
    }
    Ok(())
}

examples/reading.rs (line 36)

fn main() {
    let file = File::open("tests/exif.jpg").unwrap();
    let exif = Reader::new().read_from_container(
        &mut BufReader::new(&file)).unwrap();

    // To obtain a string representation, `Value::display_as`
    // or `Field::display_value` can be used.  To display a value with its
    // unit, call `with_unit` on the return value of `Field::display_value`.
    let tag_list = [Tag::ExifVersion,
                    Tag::PixelXDimension,
                    Tag::XResolution,
                    Tag::ImageDescription,
                    Tag::DateTime];
    for tag in tag_list {
        if let Some(field) = exif.get_field(tag, In::PRIMARY) {
            println!("{}: {}",
                     field.tag, field.display_value().with_unit(&exif));
        }
    }

    // To get unsigned integer value(s) from either of BYTE, SHORT,
    // or LONG, `Value::get_uint` or `Value::iter_uint` can be used.
    if let Some(field) = exif.get_field(Tag::PixelXDimension, In::PRIMARY) {
        if let Some(width) = field.value.get_uint(0) {
            println!("Valid width of the image is {}.", width);
        }
    }

    // To convert a Rational or SRational to an f64, `Rational::to_f64`
    // or `SRational::to_f64` can be used.
    if let Some(field) = exif.get_field(Tag::XResolution, In::PRIMARY) {
        match field.value {
            Value::Rational(ref vec) if !vec.is_empty() =>
                println!("X resolution is {}.", vec[0].to_f64()),
            _ => {},
        }
    }

    // To parse a DateTime-like field, `DateTime::from_ascii` can be used.
    if let Some(field) = exif.get_field(Tag::DateTime, In::PRIMARY) {
        match field.value {
            Value::Ascii(ref vec) if !vec.is_empty() => {
                if let Ok(datetime) = DateTime::from_ascii(&vec[0]) {
                    println!("Year of DateTime is {}.", datetime.year);
                }
            },
            _ => {},
        }
    }
}

pub fn continue_on_error(&mut self, continue_on_error: bool) -> &mut Self

Sets the option to continue parsing on non-fatal errors.

When this option is enabled, the parser will not stop on non-fatal errors and returns the results as far as they can be parsed. In such a case, read_raw and read_from_container return Error::PartialResult. The partial result and ignored errors can be obtained by Error::distill_partial_result or PartialResult::into_inner.

Note that a hard error (other than Error::PartialResult) may be returned even if this option is enabled.

Examples

use exif::Reader;
let file = std::fs::File::open("tests/exif.jpg")?;
let exif = Reader::new()
    .continue_on_error(true)
    .read_from_container(&mut std::io::BufReader::new(&file))
    .or_else(|e| e.distill_partial_result(|errors| {
        errors.iter().for_each(|e| eprintln!("Warning: {}", e));
    }))?;

Examples found in repository

examples/dumpexif.rs (line 51)

fn dump_file(path: &Path) -> Result<(), exif::Error> {
    let file = File::open(path)?;

    // To parse strictly:
    // let exif = exif::Reader::new()
    //     .read_from_container(&mut BufReader::new(&file))?;

    // To parse with continue-on-error mode:
    let exif = exif::Reader::new()
        .continue_on_error(true)
        .read_from_container(&mut BufReader::new(&file))
        .or_else(|e| e.distill_partial_result(|errors| {
            eprintln!("{}: {} warning(s)", path.display(), errors.len());
            errors.iter().for_each(|e| eprintln!("  {}", e));
        }))?;

    println!("{}", path.display());
    for f in exif.fields() {
        println!("  {}/{}: {}",
                 f.ifd_num.index(), f.tag,
                 f.display_value().with_unit(&exif));
        println!("      {:?}", f.value);
    }
    Ok(())
}

pub fn read_raw(&self, data: Vec<u8>) -> Result<Exif, Error>

Parses the Exif attributes from raw Exif data. If an error occurred, exif::Error is returned.

pub fn read_from_container<R>(&self, reader: &mut R) -> Result<Exif, Error>

where R: BufRead + Seek,

Reads an image file and parses the Exif attributes in it. If an error occurred, exif::Error is returned.

Supported formats are:

• TIFF and some RAW image formats based on it
• JPEG
• HEIF and coding-specific variations including HEIC and AVIF
• PNG
• WebP

This method is provided for the convenience even though parsing containers is basically out of the scope of this library.

Examples found in repository

examples/dumpexif.rs (line 52)

fn dump_file(path: &Path) -> Result<(), exif::Error> {
    let file = File::open(path)?;

    // To parse strictly:
    // let exif = exif::Reader::new()
    //     .read_from_container(&mut BufReader::new(&file))?;

    // To parse with continue-on-error mode:
    let exif = exif::Reader::new()
        .continue_on_error(true)
        .read_from_container(&mut BufReader::new(&file))
        .or_else(|e| e.distill_partial_result(|errors| {
            eprintln!("{}: {} warning(s)", path.display(), errors.len());
            errors.iter().for_each(|e| eprintln!("  {}", e));
        }))?;

    println!("{}", path.display());
    for f in exif.fields() {
        println!("  {}/{}: {}",
                 f.ifd_num.index(), f.tag,
                 f.display_value().with_unit(&exif));
        println!("      {:?}", f.value);
    }
    Ok(())
}

examples/reading.rs (lines 36-37)

fn main() {
    let file = File::open("tests/exif.jpg").unwrap();
    let exif = Reader::new().read_from_container(
        &mut BufReader::new(&file)).unwrap();

    // To obtain a string representation, `Value::display_as`
    // or `Field::display_value` can be used.  To display a value with its
    // unit, call `with_unit` on the return value of `Field::display_value`.
    let tag_list = [Tag::ExifVersion,
                    Tag::PixelXDimension,
                    Tag::XResolution,
                    Tag::ImageDescription,
                    Tag::DateTime];
    for tag in tag_list {
        if let Some(field) = exif.get_field(tag, In::PRIMARY) {
            println!("{}: {}",
                     field.tag, field.display_value().with_unit(&exif));
        }
    }

    // To get unsigned integer value(s) from either of BYTE, SHORT,
    // or LONG, `Value::get_uint` or `Value::iter_uint` can be used.
    if let Some(field) = exif.get_field(Tag::PixelXDimension, In::PRIMARY) {
        if let Some(width) = field.value.get_uint(0) {
            println!("Valid width of the image is {}.", width);
        }
    }

    // To convert a Rational or SRational to an f64, `Rational::to_f64`
    // or `SRational::to_f64` can be used.
    if let Some(field) = exif.get_field(Tag::XResolution, In::PRIMARY) {
        match field.value {
            Value::Rational(ref vec) if !vec.is_empty() =>
                println!("X resolution is {}.", vec[0].to_f64()),
            _ => {},
        }
    }

    // To parse a DateTime-like field, `DateTime::from_ascii` can be used.
    if let Some(field) = exif.get_field(Tag::DateTime, In::PRIMARY) {
        match field.value {
            Value::Ascii(ref vec) if !vec.is_empty() => {
                if let Ok(datetime) = DateTime::from_ascii(&vec[0]) {
                    println!("Year of DateTime is {}.", datetime.year);
                }
            },
            _ => {},
        }
    }
}