Update documentation.

src/error.rs

@@ -28,7 +28,7 @@ use std::error;
 use std::fmt;
 use std::io;
 
-/// An error type returned when parsing Exif data.
+/// An error returned when parsing of Exif data fails.
 #[derive(Debug)]
 #[non_exhaustive]
 pub enum Error {

src/lib.rs

@@ -61,17 +61,14 @@
 //! # let exif = Reader::new().read_from_container(
 //! #     &mut std::io::BufReader::new(&file)).unwrap();
 //! # macro_rules! eprintln { ($($tt:tt)*) => (panic!($($tt)*)) }
-//! // Orientation is stored as a SHORT.
+//! // Orientation is stored as a SHORT.  You could match `orientation.value`
+//! // against `Value::Short`, but the standard recommends that readers
+//! // should accept BYTE, SHORT, or LONG values for any unsigned integer
+//! // field.  `Value::get_uint` is provided for that purpose.
 //! match exif.get_field(Tag::Orientation, In::PRIMARY) {
 //!     Some(orientation) =>
-//!         // You could match `orientation.value` against `Value::Short`,
-//!         // but the standard recommends that BYTE, SHORT, or LONG should
-//!         // be accepted.  `Value::get_uint` is provided for that purpose.
 //!         match orientation.value.get_uint(0) {
-//!             Some(v @ 1..=8) => {
-//!                 println!("Orientation {}", v);
-//!                 # assert_eq!(v, 1);
-//!             },
+//!             Some(v @ 1..=8) => println!("Orientation {}", v),
 //!             _ => eprintln!("Orientation value is broken"),
 //!         },
 //!     None => eprintln!("Orientation tag is missing"),
@@ -80,11 +77,8 @@
 //! match exif.get_field(Tag::XResolution, In::PRIMARY) {
 //!     Some(xres) =>
 //!         match xres.value {
-//!             Value::Rational(ref v) if !v.is_empty() => {
-//!                 println!("XResolution {}", v[0]);
-//!                 # assert_eq!(v[0].num, 72);
-//!                 # assert_eq!(v[0].denom, 1);
-//!             },
+//!             Value::Rational(ref v) if !v.is_empty() =>
+//!                 println!("XResolution {}", v[0]),
 //!             _ => eprintln!("XResolution value is broken"),
 //!         },
 //!     None => eprintln!("XResolution tag is missing"),

src/reader.rs

@@ -63,7 +63,7 @@ pub struct Reader {
 }
 
 impl Reader {
-    /// Construct a new `Reader`.
+    /// Constructs a new `Reader`.
     pub fn new() -> Self {
         Self {}
     }

src/tag.rs

@@ -31,7 +31,7 @@ use crate::value;
 use crate::value::Value;
 use crate::util::atou16;
 
-/// A tag of a TIFF field.
+/// A tag of a TIFF/Exif field.
 ///
 /// Some well-known tags are provided as associated constants of
 /// this type.  The constant names follow the Exif specification
@@ -64,8 +64,8 @@ impl Tag {
     /// # Examples
     /// ```
     /// use exif::{Context, Tag};
-    /// assert_eq!(Tag::DateTime.context(), Context::Tiff);
-    /// assert_eq!(Tag::ExposureTime.context(), Context::Exif);
+    /// assert_eq!(Tag::XResolution.context(), Context::Tiff);
+    /// assert_eq!(Tag::DateTimeOriginal.context(), Context::Exif);
     /// ```
     #[inline]
     pub fn context(self) -> Context {
@@ -77,7 +77,8 @@ impl Tag {
     /// # Examples
     /// ```
     /// use exif::Tag;
-    /// assert_eq!(Tag::DateTime.number(), 0x132);
+    /// assert_eq!(Tag::XResolution.number(), 0x11a);
+    /// assert_eq!(Tag::DateTimeOriginal.number(), 0x9003);
     /// ```
     #[inline]
     pub fn number(self) -> u16 {
@@ -91,7 +92,7 @@ impl Tag {
     }
 
     /// Returns the default value of the tag.  `None` is returned if
-    /// it is not defined in the standard or it depends on the context.
+    /// it is not defined in the standard or it depends on another tag.
     #[inline]
     pub fn default_value(&self) -> Option<Value> {
         get_tag_info(*self).and_then(|ti| (&ti.default).into())
@@ -781,6 +782,7 @@ fn d_planarcfg(w: &mut dyn fmt::Write, value: &Value) -> fmt::Result {
 }
 
 // ResolutionUnit (TIFF 0x128)
+// FocalPlaneResolutionUnit (Exif 0xa210)
 fn d_resunit(w: &mut dyn fmt::Write, value: &Value) -> fmt::Result {
     let s = match value.get_uint(0) {
         Some(1) => "no absolute unit",

src/tiff.rs

@@ -98,7 +98,7 @@ impl IfdEntry {
     }
 }
 
-/// A TIFF field.
+/// A TIFF/Exif field.
 #[derive(Debug, Clone)]
 pub struct Field {
     /// The tag of this field.
@@ -109,7 +109,7 @@ pub struct Field {
     pub value: Value,
 }
 
-/// The IFD number.
+/// An IFD number.
 ///
 /// The IFDs are indexed from 0.  The 0th IFD is for the primary image
 /// and the 1st one is for the thumbnail.  Two associated constants,

src/value.rs

@@ -29,7 +29,7 @@ use std::fmt::Write as _;
 
 use crate::endian::Endian;
 
-/// Types and values of TIFF fields (for Exif attributes).
+/// A type and values of a TIFF/Exif field.
 #[derive(Clone)]
 pub enum Value {
     /// Vector of 8-bit unsigned integers.