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
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186

// Copyright (c) 2017, Marty Mills <daggerbot@gmail.com>
// This software is available under the terms of the zlib license.
// See COPYING.md for more information.

use std::{u8, u16, u32, u64};

/// Trait for types which can be clamped between a minimum and maximum acceptable value.
pub trait Clamp : Sized {
    fn clamp_min () -> Self;
    fn clamp_max () -> Self;

    fn clamp (self) -> Self
        where Self: PartialOrd
    {
        let min = Self::clamp_min();

        if self < min {
            return min;
        }

        let max = Self::clamp_max();

        if self > max {
            max
        } else {
            self
        }
    }
}

macro_rules! impl_clamp_uint {
    ($($ty:ident),*) => { $(
        impl Clamp for $ty {
            #[inline(always)]
            fn clamp_min () -> $ty { 0 }

            #[inline(always)]
            fn clamp_max () -> $ty { $ty::MAX }

            #[inline(always)]
            fn clamp (self) -> $ty { self }
        }
    )* };
}

macro_rules! impl_clamp_float {
    ($($ty:ty),*) => { $(
        impl Clamp for $ty {
            #[inline(always)]
            fn clamp_min () -> $ty { 0.0 }

            #[inline(always)]
            fn clamp_max () -> $ty { 1.0 }
        }
    )* };
}

impl_clamp_uint!(u8, u16, u32, u64);
impl_clamp_float!(f32, f64);

/// Interpolate from another clamped type
pub trait ClampFrom<F> {
    fn clamp_from (n: F) -> Self;
}

macro_rules! impl_clamp_from_self {
    ($($ty:ty),*) => { $(
        impl ClampFrom<$ty> for $ty {
            #[inline(always)]
            fn clamp_from (n: $ty) -> $ty { n }
        }
    )* };
}

impl_clamp_from_self!(u8, u16, u32, u64, f32, f64);

impl ClampFrom<u16> for u8 {
    #[inline(always)]
    fn clamp_from (n: u16) -> u8 { (n >> 8) as u8 }
}

impl ClampFrom<u32> for u8 {
    #[inline(always)]
    fn clamp_from (n: u32) -> u8 { (n >> 24) as u8 }
}

impl ClampFrom<u64> for u8 {
    #[inline(always)]
    fn clamp_from (n: u64) -> u8 { (n >> 56) as u8 }
}

impl ClampFrom<u8> for u16 {
    #[inline(always)]
    fn clamp_from (n: u8) -> u16 { n as u16 * 0x0101 }
}

impl ClampFrom<u32> for u16 {
    #[inline(always)]
    fn clamp_from (n: u32) -> u16 { (n >> 16) as u16 }
}

impl ClampFrom<u64> for u16 {
    #[inline(always)]
    fn clamp_from (n: u64) -> u16 { (n >> 48) as u16 }
}

impl ClampFrom<u8> for u32 {
    #[inline(always)]
    fn clamp_from (n: u8) -> u32 { n as u32 * 0x0101_0101 }
}

impl ClampFrom<u16> for u32 {
    #[inline(always)]
    fn clamp_from (n: u16) -> u32 { n as u32 * 0x0001_0001 }
}

impl ClampFrom<u64> for u32 {
    #[inline(always)]
    fn clamp_from (n: u64) -> u32 { (n >> 32) as u32 }
}

impl ClampFrom<u8> for u64 {
    #[inline(always)]
    fn clamp_from (n: u8) -> u64 { n as u64 * 0x0101_0101_0101_0101 }
}

impl ClampFrom<u16> for u64 {
    #[inline(always)]
    fn clamp_from (n: u16) -> u64 { n as u64 * 0x0001_0001_0001_0001 }
}

impl ClampFrom<u32> for u64 {
    #[inline(always)]
    fn clamp_from (n: u32) -> u64 { n as u64 * 0x0000_0001_0000_0001 }
}

impl ClampFrom<f64> for f32 {
    #[inline(always)]
    fn clamp_from (n: f64) -> f32 { n as f32 }
}

impl ClampFrom<f32> for f64 {
    #[inline(always)]
    fn clamp_from (n: f32) -> f64 { n as f64 }
}

macro_rules! impl_clamp_int_to_float {
    { $($($int:ident),+ -> $float:ident;)* } => { $($(
        impl ClampFrom<$int> for $float {
            fn clamp_from (n: $int) -> $float {
                n.clamp() as $float / $int::clamp_max() as $float
            }
        }
    )*)* };
}

macro_rules! impl_clamp_float_to_int {
    { $($float:ident -> $($int:ident),+;)* } => { $($(
        impl ClampFrom<$float> for $int {
            fn clamp_from (n: $float) -> $int {
                (n.clamp() * $int::clamp_max() as $float) as $int
            }
        }
    )*)* };
}

impl_clamp_int_to_float! {
    u8, u16, u32, u64 -> f32;
    u8, u16, u32, u64 -> f64;
}

impl_clamp_float_to_int! {
    f32 -> u8, u16, u32, u64;
    f64 -> u8, u16, u32, u64;
}

/// Interpolate into another clamped type.
pub trait ClampInto<T> {
    fn clamp_into (self) -> T;
}

impl<F, T> ClampInto<T> for F
    where T: ClampFrom<F>
{
    fn clamp_into (self) -> T { T::clamp_from(self) }
}