Struct Rational

Source

pub struct Rational {
    pub num: u32,
    pub denom: u32,
}

Expand description

An unsigned rational number, which is a pair of 32-bit unsigned integers.

Fields§

§num: u32§denom: u32

Implementations§

Source §

impl Rational

Source

pub fn to_f32(&self) -> f32

Converts the value to an f32.

Source

pub fn to_f64(&self) -> f64

Converts the value to an f64.

Examples found in repository ?

examples/reading.rs (line 67)

34fn main() {
35    let file = File::open("tests/exif.jpg").unwrap();
36    let exif = Reader::new().read_from_container(
37        &mut BufReader::new(&file)).unwrap();
38
39    // To obtain a string representation, `Value::display_as`
40    // or `Field::display_value` can be used.  To display a value with its
41    // unit, call `with_unit` on the return value of `Field::display_value`.
42    let tag_list = [Tag::ExifVersion,
43                    Tag::PixelXDimension,
44                    Tag::XResolution,
45                    Tag::ImageDescription,
46                    Tag::DateTime];
47    for tag in tag_list {
48        if let Some(field) = exif.get_field(tag, In::PRIMARY) {
49            println!("{}: {}",
50                     field.tag, field.display_value().with_unit(&exif));
51        }
52    }
53
54    // To get unsigned integer value(s) from either of BYTE, SHORT,
55    // or LONG, `Value::get_uint` or `Value::iter_uint` can be used.
56    if let Some(field) = exif.get_field(Tag::PixelXDimension, In::PRIMARY) {
57        if let Some(width) = field.value.get_uint(0) {
58            println!("Valid width of the image is {}.", width);
59        }
60    }
61
62    // To convert a Rational or SRational to an f64, `Rational::to_f64`
63    // or `SRational::to_f64` can be used.
64    if let Some(field) = exif.get_field(Tag::XResolution, In::PRIMARY) {
65        match field.value {
66            Value::Rational(ref vec) if !vec.is_empty() =>
67                println!("X resolution is {}.", vec[0].to_f64()),
68            _ => {},
69        }
70    }
71
72    // To parse a DateTime-like field, `DateTime::from_ascii` can be used.
73    if let Some(field) = exif.get_field(Tag::DateTime, In::PRIMARY) {
74        match field.value {
75            Value::Ascii(ref vec) if !vec.is_empty() => {
76                if let Ok(datetime) = DateTime::from_ascii(&vec[0]) {
77                    println!("Year of DateTime is {}.", datetime.year);
78                }
79            },
80            _ => {},
81        }
82    }
83}