epaint 0.19.0

Minimal 2D graphics library for GUI work
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130

//! Total order on floating point types.
//! Can be used for sorting, min/max computation, and other collection algorithms.

use std::cmp::Ordering;
use std::hash::{Hash, Hasher};

/// Wraps a floating-point value to add total order and hash.
/// Possible types for `T` are `f32` and `f64`.
///
/// See also [`FloatOrd`].
pub struct OrderedFloat<T>(T);

impl<T: Float> Eq for OrderedFloat<T> {}

impl<T: Float> PartialEq<Self> for OrderedFloat<T> {
    #[inline]
    fn eq(&self, other: &Self) -> bool {
        // NaNs are considered equal (equivalent) when it comes to ordering
        if self.0.is_nan() {
            other.0.is_nan()
        } else {
            self.0 == other.0
        }
    }
}

impl<T: Float> PartialOrd<Self> for OrderedFloat<T> {
    #[inline]
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        match self.0.partial_cmp(&other.0) {
            Some(ord) => Some(ord),
            None => Some(self.0.is_nan().cmp(&other.0.is_nan())),
        }
    }
}

impl<T: Float> Ord for OrderedFloat<T> {
    #[inline]
    fn cmp(&self, other: &Self) -> Ordering {
        match self.partial_cmp(other) {
            Some(ord) => ord,
            None => unreachable!(),
        }
    }
}

impl<T: Float> Hash for OrderedFloat<T> {
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.0.hash(state);
    }
}

// ----------------------------------------------------------------------------

/// Extension trait to provide `ord()` method.
///
/// Example with `f64`:
/// ```
/// use epaint::util::FloatOrd;
///
/// let array = [1.0, 2.5, 2.0];
/// let max = array.iter().max_by_key(|val| val.ord());
///
/// assert_eq!(max, Some(&2.5));
/// ```
pub trait FloatOrd {
    /// Type to provide total order, useful as key in sorted contexts.
    fn ord(self) -> OrderedFloat<Self>
    where
        Self: Sized;
}

impl FloatOrd for f32 {
    #[inline]
    fn ord(self) -> OrderedFloat<f32> {
        OrderedFloat(self)
    }
}

impl FloatOrd for f64 {
    #[inline]
    fn ord(self) -> OrderedFloat<f64> {
        OrderedFloat(self)
    }
}

// ----------------------------------------------------------------------------

/// Internal abstraction over floating point types
#[doc(hidden)]
pub trait Float: PartialOrd + PartialEq + private::FloatImpl {}

impl Float for f32 {}

impl Float for f64 {}

// Keep this trait in private module, to avoid exposing its methods as extensions in user code
mod private {
    use super::*;

    pub trait FloatImpl {
        fn is_nan(&self) -> bool;

        fn hash<H: Hasher>(&self, state: &mut H);
    }

    impl FloatImpl for f32 {
        #[inline]
        fn is_nan(&self) -> bool {
            f32::is_nan(*self)
        }

        #[inline]
        fn hash<H: Hasher>(&self, state: &mut H) {
            crate::f32_hash(state, *self);
        }
    }

    impl FloatImpl for f64 {
        #[inline]
        fn is_nan(&self) -> bool {
            f64::is_nan(*self)
        }

        #[inline]
        fn hash<H: Hasher>(&self, state: &mut H) {
            crate::f64_hash(state, *self);
        }
    }
}