tiny_skia_path/
floating_point.rs

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
// Copyright 2006 The Android Open Source Project
// Copyright 2020 Yevhenii Reizner
//
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

use crate::scalar::Scalar;

pub use strict_num::{FiniteF32, NonZeroPositiveF32, NormalizedF32};

#[cfg(all(not(feature = "std"), feature = "no-std-float"))]
use crate::NoStdFloat;

pub(crate) const FLOAT_PI: f32 = 3.14159265;

const MAX_I32_FITS_IN_F32: f32 = 2147483520.0;
const MIN_I32_FITS_IN_F32: f32 = -MAX_I32_FITS_IN_F32;

// TODO: is there an std alternative?
/// Custom float to integer conversion routines.
pub trait SaturateCast<T>: Sized {
    /// Return the closest integer for the given float.
    fn saturate_from(n: T) -> Self;
}

impl SaturateCast<f32> for i32 {
    /// Return the closest integer for the given float.
    ///
    /// Returns MAX_I32_FITS_IN_F32 for NaN.
    fn saturate_from(mut x: f32) -> Self {
        x = if x < MAX_I32_FITS_IN_F32 {
            x
        } else {
            MAX_I32_FITS_IN_F32
        };
        x = if x > MIN_I32_FITS_IN_F32 {
            x
        } else {
            MIN_I32_FITS_IN_F32
        };
        x as i32
    }
}

impl SaturateCast<f64> for i32 {
    /// Return the closest integer for the given double.
    ///
    /// Returns i32::MAX for NaN.
    fn saturate_from(mut x: f64) -> Self {
        x = if x < i32::MAX as f64 {
            x
        } else {
            i32::MAX as f64
        };
        x = if x > i32::MIN as f64 {
            x
        } else {
            i32::MIN as f64
        };
        x as i32
    }
}

/// Custom float to integer rounding routines.
#[allow(missing_docs)]
pub trait SaturateRound<T>: SaturateCast<T> {
    fn saturate_floor(n: T) -> Self;
    fn saturate_ceil(n: T) -> Self;
    fn saturate_round(n: T) -> Self;
}

impl SaturateRound<f32> for i32 {
    fn saturate_floor(x: f32) -> Self {
        Self::saturate_from(x.floor())
    }

    fn saturate_ceil(x: f32) -> Self {
        Self::saturate_from(x.ceil())
    }

    fn saturate_round(x: f32) -> Self {
        Self::saturate_from(x.floor() + 0.5)
    }
}

/// Return the float as a 2s compliment int. Just to be used to compare floats
/// to each other or against positive float-bit-constants (like 0). This does
/// not return the int equivalent of the float, just something cheaper for
/// compares-only.
pub(crate) fn f32_as_2s_compliment(x: f32) -> i32 {
    sign_bit_to_2s_compliment(bytemuck::cast(x))
}

/// Convert a sign-bit int (i.e. float interpreted as int) into a 2s compliement
/// int. This also converts -0 (0x80000000) to 0. Doing this to a float allows
/// it to be compared using normal C operators (<, <=, etc.)
fn sign_bit_to_2s_compliment(mut x: i32) -> i32 {
    if x < 0 {
        x &= 0x7FFFFFFF;
        x = -x;
    }

    x
}

/// An immutable `f32` that is larger than 0 but less then 1.
#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Default, Debug)]
#[repr(transparent)]
pub struct NormalizedF32Exclusive(FiniteF32);

impl NormalizedF32Exclusive {
    /// Just a random, valid number.
    pub const ANY: Self = Self::HALF;

    /// A predefined 0.5 value.
    pub const HALF: Self = NormalizedF32Exclusive(unsafe { FiniteF32::new_unchecked(0.5) });

    /// Creates a `NormalizedF32Exclusive`.
    pub fn new(n: f32) -> Option<Self> {
        if n > 0.0 && n < 1.0 {
            // `n` is guarantee to be finite after the bounds check.
            FiniteF32::new(n).map(NormalizedF32Exclusive)
        } else {
            None
        }
    }

    /// Creates a `NormalizedF32Exclusive` clamping the given value.
    ///
    /// Returns zero in case of NaN or infinity.
    pub fn new_bounded(n: f32) -> Self {
        let n = n.bound(f32::EPSILON, 1.0 - f32::EPSILON);
        // `n` is guarantee to be finite after clamping.
        debug_assert!(n.is_finite());
        NormalizedF32Exclusive(unsafe { FiniteF32::new_unchecked(n) })
    }

    /// Returns the value as a primitive type.
    pub fn get(self) -> f32 {
        self.0.get()
    }

    /// Returns the value as a `FiniteF32`.
    pub fn to_normalized(self) -> NormalizedF32 {
        // NormalizedF32 is (0,1), while NormalizedF32 is [0,1], so it will always fit.
        unsafe { NormalizedF32::new_unchecked(self.0.get()) }
    }
}