Update the documents for version 0.4.
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src/lib.rs
89
src/lib.rs
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@ -44,19 +44,88 @@
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//! }
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//! ```
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//!
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//! # Compatibility
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//! # Upgrade Guide (0.3.x to 0.4.x)
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//!
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//! Major changes between 0.3.1 and 0.4 are listed below.
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//! ## API compatibilities
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//!
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//! * The constants in tag module (`tag::TagName`) have been removed.
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//! Use `Tag::TagName` instead.
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//! * Sturct `In` (IFD number) has been added to indicate primary/thumbnail
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//! images, which were distinguished by `bool` previously. Function
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//! parameters and struct members now take `In`s instead of `bool`s.
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//! `Field::thumbnail` was renamed to `Field::ifd_num` accordingly.
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//! * `Value` became a self-contained type. The structures of `Value::Ascii`
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//! and `Value::Undefined` have been changed to use Vec<u8> instead of &[u8].
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//! * Use struct `In` instead of `bool` to indicate primary/thumbnail images.
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//! - On `Reader::get_field`, the old code in 0.3.x:
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//! ```ignore
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//! reader.get_field(Tag::DateTime, false)
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//! ```
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//! The new code in 0.4.x:
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//! ```
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//! # use exif::{In, Reader, Tag};
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//! # let file = std::fs::File::open("tests/exif.tif").unwrap();
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//! # let reader = Reader::new(
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//! # &mut std::io::BufReader::new(&file)).unwrap();
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//! reader.get_field(Tag::DateTime, In::PRIMARY)
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//! # ;
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//! ```
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//! As an additional feature, access to the 2nd or further IFD,
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//! which some RAW formats may have, is also possible in 0.4.x:
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//! ```
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//! # use exif::{In, Reader, Tag};
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//! # let file = std::fs::File::open("tests/exif.tif").unwrap();
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//! # let reader = Reader::new(
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//! # &mut std::io::BufReader::new(&file)).unwrap();
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//! reader.get_field(Tag::ImageWidth, In(2))
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//! # ;
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//! ```
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//! - On `Field`, the old code in 0.3.x:
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//! ```ignore
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//! if field.thumbnail {
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//! // for the thumbnail image
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//! } else {
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//! // for the primary image
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//! }
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//! ```
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//! The new code in 0.4.x:
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//! ```
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//! # use exif::{In, Reader};
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//! # let file = std::fs::File::open("tests/exif.tif").unwrap();
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//! # let reader = Reader::new(
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//! # &mut std::io::BufReader::new(&file)).unwrap();
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//! # let field = reader.fields().next().unwrap();
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//! match field.ifd_num {
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//! In::PRIMARY => {}, // for the primary image
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//! In::THUMBNAIL => {}, // for the thumbnail image
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//! _ => {},
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//! }
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//! ```
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//! * `Reader::fields` now returns an iterator instead of a slice.
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//! * Enum variants of `Context` and `Error` are no longer exhaustive.
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//! You need a wildcard arm (`_`) in a match expression.
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//! * The associated value of `Value::Undefined` and `Value::Ascii` has
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//! been changed from a slice to a `Vec`.
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//!
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//! ## Other new features
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//!
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//! * `Field::display_value` has been introduced.
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//! It is usually handier than `Value::display_as`.
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//! ```
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//! # let file = std::fs::File::open("tests/exif.tif").unwrap();
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//! # let reader = exif::Reader::new(
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//! # &mut std::io::BufReader::new(&file)).unwrap();
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//! # let field = reader.fields().next().unwrap();
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//! assert_eq!(field.display_value().to_string(),
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//! field.value.display_as(field.tag).to_string());
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//! ```
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//! * Displaying a value with its unit is supported.
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//! ```
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//! # let file = std::fs::File::open("tests/exif.tif").unwrap();
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//! # let reader = exif::Reader::new(
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//! # &mut std::io::BufReader::new(&file)).unwrap();
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//! # let field = reader.fields().next().unwrap();
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//! // Display the value only.
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//! println!("{}", field.display_value());
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//! // Display the value with its unit. If the unit depends on another
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//! // field, it is taken from the reader.
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//! println!("{}", field.display_value().with_unit(&reader));
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//! ```
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//! * `Value` and `Field` are self-contained and no longer borrow the raw
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//! buffer or `Reader` (thanks to the change of `Value::Undefined`
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//! and `Value::Ascii` described above).
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pub use error::Error;
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pub use jpeg::get_exif_attr as get_exif_attr_from_jpeg;
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