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
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
// Copyright 2013 The Servo Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use super::UnknownUnit;
use crate::approxord::{max, min};
use crate::num::*;
use crate::point::{point2, Point2D};
use crate::rect::Rect;
use crate::scale::Scale;
use crate::side_offsets::SideOffsets2D;
use crate::size::Size2D;
use crate::vector::{vec2, Vector2D};

#[cfg(feature = "bytemuck")]
use bytemuck::{Pod, Zeroable};
use num_traits::{Float, NumCast};
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};

use core::borrow::Borrow;
use core::cmp::PartialOrd;
use core::fmt;
use core::hash::{Hash, Hasher};
use core::ops::{Add, Div, DivAssign, Mul, MulAssign, Range, Sub};

/// A 2d axis aligned rectangle represented by its minimum and maximum coordinates.
///
/// # Representation
///
/// This struct is similar to [`Rect`], but stores rectangle as two endpoints
/// instead of origin point and size. Such representation has several advantages over
/// [`Rect`] representation:
/// - Several operations are more efficient with `Box2D`, including [`intersection`],
///   [`union`], and point-in-rect.
/// - The representation is less susceptible to overflow. With [`Rect`], computation
///   of second point can overflow for a large range of values of origin and size.
///   However, with `Box2D`, computation of [`size`] cannot overflow if the coordinates
///   are signed and the resulting size is unsigned.
///
/// A known disadvantage of `Box2D` is that translating the rectangle requires translating
/// both points, whereas translating [`Rect`] only requires translating one point.
///
/// # Empty box
///
/// A box is considered empty (see [`is_empty`]) if any of the following is true:
/// - it's area is empty,
/// - it's area is negative (`min.x > max.x` or `min.y > max.y`),
/// - it contains NaNs.
///
/// [`intersection`]: Self::intersection
/// [`is_empty`]: Self::is_empty
/// [`union`]: Self::union
/// [`size`]: Self::size
#[repr(C)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(
    feature = "serde",
    serde(bound(serialize = "T: Serialize", deserialize = "T: Deserialize<'de>"))
)]
pub struct Box2D<T, U> {
    pub min: Point2D<T, U>,
    pub max: Point2D<T, U>,
}

impl<T: Hash, U> Hash for Box2D<T, U> {
    fn hash<H: Hasher>(&self, h: &mut H) {
        self.min.hash(h);
        self.max.hash(h);
    }
}

impl<T: Copy, U> Copy for Box2D<T, U> {}

impl<T: Clone, U> Clone for Box2D<T, U> {
    fn clone(&self) -> Self {
        Self::new(self.min.clone(), self.max.clone())
    }
}

impl<T: PartialEq, U> PartialEq for Box2D<T, U> {
    fn eq(&self, other: &Self) -> bool {
        self.min.eq(&other.min) && self.max.eq(&other.max)
    }
}

impl<T: Eq, U> Eq for Box2D<T, U> {}

impl<T: fmt::Debug, U> fmt::Debug for Box2D<T, U> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.debug_tuple("Box2D")
            .field(&self.min)
            .field(&self.max)
            .finish()
    }
}

#[cfg(feature = "arbitrary")]
impl<'a, T, U> arbitrary::Arbitrary<'a> for Box2D<T, U>
where
    T: arbitrary::Arbitrary<'a>,
{
    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
        Ok(Box2D::new(
            arbitrary::Arbitrary::arbitrary(u)?,
            arbitrary::Arbitrary::arbitrary(u)?,
        ))
    }
}

#[cfg(feature = "bytemuck")]
unsafe impl<T: Zeroable, U> Zeroable for Box2D<T, U> {}

#[cfg(feature = "bytemuck")]
unsafe impl<T: Pod, U: 'static> Pod for Box2D<T, U> {}

impl<T, U> Box2D<T, U> {
    /// Constructor.
    #[inline]
    pub const fn new(min: Point2D<T, U>, max: Point2D<T, U>) -> Self {
        Box2D { min, max }
    }

    /// Constructor.
    #[inline]
    pub fn from_origin_and_size(origin: Point2D<T, U>, size: Size2D<T, U>) -> Self
    where
        T: Copy + Add<T, Output = T>,
    {
        Box2D {
            min: origin,
            max: point2(origin.x + size.width, origin.y + size.height),
        }
    }

    /// Creates a `Box2D` of the given size, at offset zero.
    #[inline]
    pub fn from_size(size: Size2D<T, U>) -> Self
    where
        T: Zero,
    {
        Box2D {
            min: Point2D::zero(),
            max: point2(size.width, size.height),
        }
    }
}

impl<T, U> Box2D<T, U>
where
    T: PartialOrd,
{
    /// Returns `true` if the box has a negative area.
    ///
    /// The common interpretation for a negative box is to consider it empty. It can be obtained
    /// by calculating the intersection of two boxes that do not intersect.
    #[inline]
    pub fn is_negative(&self) -> bool {
        self.max.x < self.min.x || self.max.y < self.min.y
    }

    /// Returns `true` if the size is zero, negative or NaN.
    #[inline]
    pub fn is_empty(&self) -> bool {
        !(self.max.x > self.min.x && self.max.y > self.min.y)
    }

    /// Returns `true` if the two boxes intersect.
    #[inline]
    pub fn intersects(&self, other: &Self) -> bool {
        // Use bitwise and instead of && to avoid emitting branches.
        (self.min.x < other.max.x)
            & (self.max.x > other.min.x)
            & (self.min.y < other.max.y)
            & (self.max.y > other.min.y)
    }

    /// Returns `true` if this box2d contains the point `p`. A point is considered
    /// in the box2d if it lies on the left or top edges, but outside if it lies
    /// on the right or bottom edges.
    #[inline]
    pub fn contains(&self, p: Point2D<T, U>) -> bool {
        // Use bitwise and instead of && to avoid emitting branches.
        (self.min.x <= p.x) & (p.x < self.max.x) & (self.min.y <= p.y) & (p.y < self.max.y)
    }

    /// Returns `true` if this box contains the point `p`. A point is considered
    /// in the box2d if it lies on any edge of the box2d.
    #[inline]
    pub fn contains_inclusive(&self, p: Point2D<T, U>) -> bool {
        // Use bitwise and instead of && to avoid emitting branches.
        (self.min.x <= p.x) & (p.x <= self.max.x) & (self.min.y <= p.y) & (p.y <= self.max.y)
    }

    /// Returns `true` if this box contains the interior of the other box. Always
    /// returns `true` if other is empty, and always returns `false` if other is
    /// nonempty but this box is empty.
    #[inline]
    pub fn contains_box(&self, other: &Self) -> bool {
        other.is_empty()
            || ((self.min.x <= other.min.x)
                & (other.max.x <= self.max.x)
                & (self.min.y <= other.min.y)
                & (other.max.y <= self.max.y))
    }
}

impl<T, U> Box2D<T, U>
where
    T: Copy + PartialOrd,
{
    #[inline]
    pub fn to_non_empty(&self) -> Option<Self> {
        if self.is_empty() {
            return None;
        }

        Some(*self)
    }

    /// Computes the intersection of two boxes, returning `None` if the boxes do not intersect.
    #[inline]
    pub fn intersection(&self, other: &Self) -> Option<Self> {
        let b = self.intersection_unchecked(other);

        if b.is_empty() {
            return None;
        }

        Some(b)
    }

    /// Computes the intersection of two boxes without check whether they do intersect.
    ///
    /// The result is a negative box if the boxes do not intersect.
    /// This can be useful for computing the intersection of more than two boxes, as
    /// it is possible to chain multiple `intersection_unchecked` calls and check for
    /// empty/negative result at the end.
    #[inline]
    pub fn intersection_unchecked(&self, other: &Self) -> Self {
        Box2D {
            min: point2(max(self.min.x, other.min.x), max(self.min.y, other.min.y)),
            max: point2(min(self.max.x, other.max.x), min(self.max.y, other.max.y)),
        }
    }

    /// Computes the union of two boxes.
    ///
    /// If either of the boxes is empty, the other one is returned.
    #[inline]
    pub fn union(&self, other: &Self) -> Self {
        if other.is_empty() {
            return *self;
        }
        if self.is_empty() {
            return *other;
        }

        Box2D {
            min: point2(min(self.min.x, other.min.x), min(self.min.y, other.min.y)),
            max: point2(max(self.max.x, other.max.x), max(self.max.y, other.max.y)),
        }
    }
}

impl<T, U> Box2D<T, U>
where
    T: Copy + Add<T, Output = T>,
{
    /// Returns the same box, translated by a vector.
    #[inline]
    pub fn translate(&self, by: Vector2D<T, U>) -> Self {
        Box2D {
            min: self.min + by,
            max: self.max + by,
        }
    }
}

impl<T, U> Box2D<T, U>
where
    T: Copy + Sub<T, Output = T>,
{
    #[inline]
    pub fn size(&self) -> Size2D<T, U> {
        (self.max - self.min).to_size()
    }

    /// Change the size of the box by adjusting the max endpoint
    /// without modifying the min endpoint.
    #[inline]
    pub fn set_size(&mut self, size: Size2D<T, U>) {
        let diff = (self.size() - size).to_vector();
        self.max -= diff;
    }

    #[inline]
    pub fn width(&self) -> T {
        self.max.x - self.min.x
    }

    #[inline]
    pub fn height(&self) -> T {
        self.max.y - self.min.y
    }

    #[inline]
    pub fn to_rect(&self) -> Rect<T, U> {
        Rect {
            origin: self.min,
            size: self.size(),
        }
    }
}

impl<T, U> Box2D<T, U>
where
    T: Copy + Add<T, Output = T> + Sub<T, Output = T>,
{
    /// Inflates the box by the specified sizes on each side respectively.
    #[inline]
    #[must_use]
    pub fn inflate(&self, width: T, height: T) -> Self {
        Box2D {
            min: point2(self.min.x - width, self.min.y - height),
            max: point2(self.max.x + width, self.max.y + height),
        }
    }

    /// Calculate the size and position of an inner box.
    ///
    /// Subtracts the side offsets from all sides. The horizontal, vertical
    /// and applicate offsets must not be larger than the original side length.
    pub fn inner_box(&self, offsets: SideOffsets2D<T, U>) -> Self {
        Box2D {
            min: self.min + vec2(offsets.left, offsets.top),
            max: self.max - vec2(offsets.right, offsets.bottom),
        }
    }

    /// Calculate the b and position of an outer box.
    ///
    /// Add the offsets to all sides. The expanded box is returned.
    pub fn outer_box(&self, offsets: SideOffsets2D<T, U>) -> Self {
        Box2D {
            min: self.min - vec2(offsets.left, offsets.top),
            max: self.max + vec2(offsets.right, offsets.bottom),
        }
    }
}

impl<T, U> Box2D<T, U>
where
    T: Copy + Zero + PartialOrd,
{
    /// Returns the smallest box containing all of the provided points.
    pub fn from_points<I>(points: I) -> Self
    where
        I: IntoIterator,
        I::Item: Borrow<Point2D<T, U>>,
    {
        let mut points = points.into_iter();

        let (mut min_x, mut min_y) = match points.next() {
            Some(first) => first.borrow().to_tuple(),
            None => return Box2D::zero(),
        };

        let (mut max_x, mut max_y) = (min_x, min_y);
        for point in points {
            let p = point.borrow();
            if p.x < min_x {
                min_x = p.x
            }
            if p.x > max_x {
                max_x = p.x
            }
            if p.y < min_y {
                min_y = p.y
            }
            if p.y > max_y {
                max_y = p.y
            }
        }

        Box2D {
            min: point2(min_x, min_y),
            max: point2(max_x, max_y),
        }
    }
}

impl<T, U> Box2D<T, U>
where
    T: Copy + One + Add<Output = T> + Sub<Output = T> + Mul<Output = T>,
{
    /// Linearly interpolate between this box and another box.
    #[inline]
    pub fn lerp(&self, other: Self, t: T) -> Self {
        Self::new(self.min.lerp(other.min, t), self.max.lerp(other.max, t))
    }
}

impl<T, U> Box2D<T, U>
where
    T: Copy + One + Add<Output = T> + Div<Output = T>,
{
    pub fn center(&self) -> Point2D<T, U> {
        let two = T::one() + T::one();
        (self.min + self.max.to_vector()) / two
    }
}

impl<T, U> Box2D<T, U>
where
    T: Copy + Mul<T, Output = T> + Sub<T, Output = T>,
{
    #[inline]
    pub fn area(&self) -> T {
        let size = self.size();
        size.width * size.height
    }
}

impl<T, U> Box2D<T, U>
where
    T: Zero,
{
    /// Constructor, setting all sides to zero.
    pub fn zero() -> Self {
        Box2D::new(Point2D::zero(), Point2D::zero())
    }
}

impl<T: Copy + Mul, U> Mul<T> for Box2D<T, U> {
    type Output = Box2D<T::Output, U>;

    #[inline]
    fn mul(self, scale: T) -> Self::Output {
        Box2D::new(self.min * scale, self.max * scale)
    }
}

impl<T: Copy + MulAssign, U> MulAssign<T> for Box2D<T, U> {
    #[inline]
    fn mul_assign(&mut self, scale: T) {
        *self *= Scale::new(scale);
    }
}

impl<T: Copy + Div, U> Div<T> for Box2D<T, U> {
    type Output = Box2D<T::Output, U>;

    #[inline]
    fn div(self, scale: T) -> Self::Output {
        Box2D::new(self.min / scale, self.max / scale)
    }
}

impl<T: Copy + DivAssign, U> DivAssign<T> for Box2D<T, U> {
    #[inline]
    fn div_assign(&mut self, scale: T) {
        *self /= Scale::new(scale);
    }
}

impl<T: Copy + Mul, U1, U2> Mul<Scale<T, U1, U2>> for Box2D<T, U1> {
    type Output = Box2D<T::Output, U2>;

    #[inline]
    fn mul(self, scale: Scale<T, U1, U2>) -> Self::Output {
        Box2D::new(self.min * scale, self.max * scale)
    }
}

impl<T: Copy + MulAssign, U> MulAssign<Scale<T, U, U>> for Box2D<T, U> {
    #[inline]
    fn mul_assign(&mut self, scale: Scale<T, U, U>) {
        self.min *= scale;
        self.max *= scale;
    }
}

impl<T: Copy + Div, U1, U2> Div<Scale<T, U1, U2>> for Box2D<T, U2> {
    type Output = Box2D<T::Output, U1>;

    #[inline]
    fn div(self, scale: Scale<T, U1, U2>) -> Self::Output {
        Box2D::new(self.min / scale, self.max / scale)
    }
}

impl<T: Copy + DivAssign, U> DivAssign<Scale<T, U, U>> for Box2D<T, U> {
    #[inline]
    fn div_assign(&mut self, scale: Scale<T, U, U>) {
        self.min /= scale;
        self.max /= scale;
    }
}

impl<T, U> Box2D<T, U>
where
    T: Copy,
{
    #[inline]
    pub fn x_range(&self) -> Range<T> {
        self.min.x..self.max.x
    }

    #[inline]
    pub fn y_range(&self) -> Range<T> {
        self.min.y..self.max.y
    }

    /// Drop the units, preserving only the numeric value.
    #[inline]
    pub fn to_untyped(&self) -> Box2D<T, UnknownUnit> {
        Box2D::new(self.min.to_untyped(), self.max.to_untyped())
    }

    /// Tag a unitless value with units.
    #[inline]
    pub fn from_untyped(c: &Box2D<T, UnknownUnit>) -> Box2D<T, U> {
        Box2D::new(Point2D::from_untyped(c.min), Point2D::from_untyped(c.max))
    }

    /// Cast the unit
    #[inline]
    pub fn cast_unit<V>(&self) -> Box2D<T, V> {
        Box2D::new(self.min.cast_unit(), self.max.cast_unit())
    }

    #[inline]
    pub fn scale<S: Copy>(&self, x: S, y: S) -> Self
    where
        T: Mul<S, Output = T>,
    {
        Box2D {
            min: point2(self.min.x * x, self.min.y * y),
            max: point2(self.max.x * x, self.max.y * y),
        }
    }
}

impl<T: NumCast + Copy, U> Box2D<T, U> {
    /// Cast from one numeric representation to another, preserving the units.
    ///
    /// When casting from floating point to integer coordinates, the decimals are truncated
    /// as one would expect from a simple cast, but this behavior does not always make sense
    /// geometrically. Consider using [`round`], [`round_in`] or [`round_out`] before casting.
    ///
    /// [`round`]: Self::round
    /// [`round_in`]: Self::round_in
    /// [`round_out`]: Self::round_out
    #[inline]
    pub fn cast<NewT: NumCast>(&self) -> Box2D<NewT, U> {
        Box2D::new(self.min.cast(), self.max.cast())
    }

    /// Fallible cast from one numeric representation to another, preserving the units.
    ///
    /// When casting from floating point to integer coordinates, the decimals are truncated
    /// as one would expect from a simple cast, but this behavior does not always make sense
    /// geometrically. Consider using [`round`], [`round_in`] or [`round_out`] before casting.
    ///
    /// [`round`]: Self::round
    /// [`round_in`]: Self::round_in
    /// [`round_out`]: Self::round_out
    pub fn try_cast<NewT: NumCast>(&self) -> Option<Box2D<NewT, U>> {
        match (self.min.try_cast(), self.max.try_cast()) {
            (Some(a), Some(b)) => Some(Box2D::new(a, b)),
            _ => None,
        }
    }

    // Convenience functions for common casts

    /// Cast into an `f32` box.
    #[inline]
    pub fn to_f32(&self) -> Box2D<f32, U> {
        self.cast()
    }

    /// Cast into an `f64` box.
    #[inline]
    pub fn to_f64(&self) -> Box2D<f64, U> {
        self.cast()
    }

    /// Cast into an `usize` box, truncating decimals if any.
    ///
    /// When casting from floating point boxes, it is worth considering whether
    /// to `round()`, `round_in()` or `round_out()` before the cast in order to
    /// obtain the desired conversion behavior.
    #[inline]
    pub fn to_usize(&self) -> Box2D<usize, U> {
        self.cast()
    }

    /// Cast into an `u32` box, truncating decimals if any.
    ///
    /// When casting from floating point boxes, it is worth considering whether
    /// to `round()`, `round_in()` or `round_out()` before the cast in order to
    /// obtain the desired conversion behavior.
    #[inline]
    pub fn to_u32(&self) -> Box2D<u32, U> {
        self.cast()
    }

    /// Cast into an `i32` box, truncating decimals if any.
    ///
    /// When casting from floating point boxes, it is worth considering whether
    /// to `round()`, `round_in()` or `round_out()` before the cast in order to
    /// obtain the desired conversion behavior.
    #[inline]
    pub fn to_i32(&self) -> Box2D<i32, U> {
        self.cast()
    }

    /// Cast into an `i64` box, truncating decimals if any.
    ///
    /// When casting from floating point boxes, it is worth considering whether
    /// to `round()`, `round_in()` or `round_out()` before the cast in order to
    /// obtain the desired conversion behavior.
    #[inline]
    pub fn to_i64(&self) -> Box2D<i64, U> {
        self.cast()
    }
}

impl<T: Float, U> Box2D<T, U> {
    /// Returns `true` if all members are finite.
    #[inline]
    pub fn is_finite(self) -> bool {
        self.min.is_finite() && self.max.is_finite()
    }
}

impl<T, U> Box2D<T, U>
where
    T: Round,
{
    /// Return a box with edges rounded to integer coordinates, such that
    /// the returned box has the same set of pixel centers as the original
    /// one.
    /// Values equal to 0.5 round up.
    /// Suitable for most places where integral device coordinates
    /// are needed, but note that any translation should be applied first to
    /// avoid pixel rounding errors.
    /// Note that this is *not* rounding to nearest integer if the values are negative.
    /// They are always rounding as floor(n + 0.5).
    #[must_use]
    pub fn round(&self) -> Self {
        Box2D::new(self.min.round(), self.max.round())
    }
}

impl<T, U> Box2D<T, U>
where
    T: Floor + Ceil,
{
    /// Return a box with faces/edges rounded to integer coordinates, such that
    /// the original box contains the resulting box.
    #[must_use]
    pub fn round_in(&self) -> Self {
        let min = self.min.ceil();
        let max = self.max.floor();
        Box2D { min, max }
    }

    /// Return a box with faces/edges rounded to integer coordinates, such that
    /// the original box is contained in the resulting box.
    #[must_use]
    pub fn round_out(&self) -> Self {
        let min = self.min.floor();
        let max = self.max.ceil();
        Box2D { min, max }
    }
}

impl<T, U> From<Size2D<T, U>> for Box2D<T, U>
where
    T: Copy + Zero + PartialOrd,
{
    fn from(b: Size2D<T, U>) -> Self {
        Self::from_size(b)
    }
}

impl<T: Default, U> Default for Box2D<T, U> {
    fn default() -> Self {
        Box2D {
            min: Default::default(),
            max: Default::default(),
        }
    }
}

#[cfg(test)]
mod tests {
    use crate::default::Box2D;
    use crate::side_offsets::SideOffsets2D;
    use crate::{point2, size2, vec2, Point2D};
    //use super::*;

    #[test]
    fn test_size() {
        let b = Box2D::new(point2(-10.0, -10.0), point2(10.0, 10.0));
        assert_eq!(b.size().width, 20.0);
        assert_eq!(b.size().height, 20.0);
    }

    #[test]
    fn test_width_height() {
        let b = Box2D::new(point2(-10.0, -10.0), point2(10.0, 10.0));
        assert!(b.width() == 20.0);
        assert!(b.height() == 20.0);
    }

    #[test]
    fn test_center() {
        let b = Box2D::new(point2(-10.0, -10.0), point2(10.0, 10.0));
        assert_eq!(b.center(), Point2D::zero());
    }

    #[test]
    fn test_area() {
        let b = Box2D::new(point2(-10.0, -10.0), point2(10.0, 10.0));
        assert_eq!(b.area(), 400.0);
    }

    #[test]
    fn test_from_points() {
        let b = Box2D::from_points(&[point2(50.0, 160.0), point2(100.0, 25.0)]);
        assert_eq!(b.min, point2(50.0, 25.0));
        assert_eq!(b.max, point2(100.0, 160.0));
    }

    #[test]
    fn test_round_in() {
        let b = Box2D::from_points(&[point2(-25.5, -40.4), point2(60.3, 36.5)]).round_in();
        assert_eq!(b.min.x, -25.0);
        assert_eq!(b.min.y, -40.0);
        assert_eq!(b.max.x, 60.0);
        assert_eq!(b.max.y, 36.0);
    }

    #[test]
    fn test_round_out() {
        let b = Box2D::from_points(&[point2(-25.5, -40.4), point2(60.3, 36.5)]).round_out();
        assert_eq!(b.min.x, -26.0);
        assert_eq!(b.min.y, -41.0);
        assert_eq!(b.max.x, 61.0);
        assert_eq!(b.max.y, 37.0);
    }

    #[test]
    fn test_round() {
        let b = Box2D::from_points(&[point2(-25.5, -40.4), point2(60.3, 36.5)]).round();
        assert_eq!(b.min.x, -25.0);
        assert_eq!(b.min.y, -40.0);
        assert_eq!(b.max.x, 60.0);
        assert_eq!(b.max.y, 37.0);
    }

    #[test]
    fn test_from_size() {
        let b = Box2D::from_size(size2(30.0, 40.0));
        assert!(b.min == Point2D::zero());
        assert!(b.size().width == 30.0);
        assert!(b.size().height == 40.0);
    }

    #[test]
    fn test_inner_box() {
        let b = Box2D::from_points(&[point2(50.0, 25.0), point2(100.0, 160.0)]);
        let b = b.inner_box(SideOffsets2D::new(10.0, 20.0, 5.0, 10.0));
        assert_eq!(b.max.x, 80.0);
        assert_eq!(b.max.y, 155.0);
        assert_eq!(b.min.x, 60.0);
        assert_eq!(b.min.y, 35.0);
    }

    #[test]
    fn test_outer_box() {
        let b = Box2D::from_points(&[point2(50.0, 25.0), point2(100.0, 160.0)]);
        let b = b.outer_box(SideOffsets2D::new(10.0, 20.0, 5.0, 10.0));
        assert_eq!(b.max.x, 120.0);
        assert_eq!(b.max.y, 165.0);
        assert_eq!(b.min.x, 40.0);
        assert_eq!(b.min.y, 15.0);
    }

    #[test]
    fn test_translate() {
        let size = size2(15.0, 15.0);
        let mut center = (size / 2.0).to_vector().to_point();
        let b = Box2D::from_size(size);
        assert_eq!(b.center(), center);
        let translation = vec2(10.0, 2.5);
        let b = b.translate(translation);
        center += translation;
        assert_eq!(b.center(), center);
        assert_eq!(b.max.x, 25.0);
        assert_eq!(b.max.y, 17.5);
        assert_eq!(b.min.x, 10.0);
        assert_eq!(b.min.y, 2.5);
    }

    #[test]
    fn test_union() {
        let b1 = Box2D::from_points(&[point2(-20.0, -20.0), point2(0.0, 20.0)]);
        let b2 = Box2D::from_points(&[point2(0.0, 20.0), point2(20.0, -20.0)]);
        let b = b1.union(&b2);
        assert_eq!(b.max.x, 20.0);
        assert_eq!(b.max.y, 20.0);
        assert_eq!(b.min.x, -20.0);
        assert_eq!(b.min.y, -20.0);
    }

    #[test]
    fn test_intersects() {
        let b1 = Box2D::from_points(&[point2(-15.0, -20.0), point2(10.0, 20.0)]);
        let b2 = Box2D::from_points(&[point2(-10.0, 20.0), point2(15.0, -20.0)]);
        assert!(b1.intersects(&b2));
    }

    #[test]
    fn test_intersection_unchecked() {
        let b1 = Box2D::from_points(&[point2(-15.0, -20.0), point2(10.0, 20.0)]);
        let b2 = Box2D::from_points(&[point2(-10.0, 20.0), point2(15.0, -20.0)]);
        let b = b1.intersection_unchecked(&b2);
        assert_eq!(b.max.x, 10.0);
        assert_eq!(b.max.y, 20.0);
        assert_eq!(b.min.x, -10.0);
        assert_eq!(b.min.y, -20.0);
    }

    #[test]
    fn test_intersection() {
        let b1 = Box2D::from_points(&[point2(-15.0, -20.0), point2(10.0, 20.0)]);
        let b2 = Box2D::from_points(&[point2(-10.0, 20.0), point2(15.0, -20.0)]);
        assert!(b1.intersection(&b2).is_some());

        let b1 = Box2D::from_points(&[point2(-15.0, -20.0), point2(-10.0, 20.0)]);
        let b2 = Box2D::from_points(&[point2(10.0, 20.0), point2(15.0, -20.0)]);
        assert!(b1.intersection(&b2).is_none());
    }

    #[test]
    fn test_scale() {
        let b = Box2D::from_points(&[point2(-10.0, -10.0), point2(10.0, 10.0)]);
        let b = b.scale(0.5, 0.5);
        assert_eq!(b.max.x, 5.0);
        assert_eq!(b.max.y, 5.0);
        assert_eq!(b.min.x, -5.0);
        assert_eq!(b.min.y, -5.0);
    }

    #[test]
    fn test_lerp() {
        let b1 = Box2D::from_points(&[point2(-20.0, -20.0), point2(-10.0, -10.0)]);
        let b2 = Box2D::from_points(&[point2(10.0, 10.0), point2(20.0, 20.0)]);
        let b = b1.lerp(b2, 0.5);
        assert_eq!(b.center(), Point2D::zero());
        assert_eq!(b.size().width, 10.0);
        assert_eq!(b.size().height, 10.0);
    }

    #[test]
    fn test_contains() {
        let b = Box2D::from_points(&[point2(-20.0, -20.0), point2(20.0, 20.0)]);
        assert!(b.contains(point2(-15.3, 10.5)));
    }

    #[test]
    fn test_contains_box() {
        let b1 = Box2D::from_points(&[point2(-20.0, -20.0), point2(20.0, 20.0)]);
        let b2 = Box2D::from_points(&[point2(-14.3, -16.5), point2(6.7, 17.6)]);
        assert!(b1.contains_box(&b2));
    }

    #[test]
    fn test_inflate() {
        let b = Box2D::from_points(&[point2(-20.0, -20.0), point2(20.0, 20.0)]);
        let b = b.inflate(10.0, 5.0);
        assert_eq!(b.size().width, 60.0);
        assert_eq!(b.size().height, 50.0);
        assert_eq!(b.center(), Point2D::zero());
    }

    #[test]
    fn test_is_empty() {
        for i in 0..2 {
            let mut coords_neg = [-20.0, -20.0];
            let mut coords_pos = [20.0, 20.0];
            coords_neg[i] = 0.0;
            coords_pos[i] = 0.0;
            let b = Box2D::from_points(&[Point2D::from(coords_neg), Point2D::from(coords_pos)]);
            assert!(b.is_empty());
        }
    }

    #[test]
    #[rustfmt::skip]
    fn test_nan_empty() {
        use std::f32::NAN;
        assert!(Box2D { min: point2(NAN, 2.0), max: point2(1.0, 3.0) }.is_empty());
        assert!(Box2D { min: point2(0.0, NAN), max: point2(1.0, 2.0) }.is_empty());
        assert!(Box2D { min: point2(1.0, -2.0), max: point2(NAN, 2.0) }.is_empty());
        assert!(Box2D { min: point2(1.0, -2.0), max: point2(0.0, NAN) }.is_empty());
    }

    #[test]
    fn test_from_origin_and_size() {
        let b = Box2D::from_origin_and_size(point2(1.0, 2.0), size2(3.0, 4.0));
        assert_eq!(b.min, point2(1.0, 2.0));
        assert_eq!(b.size(), size2(3.0, 4.0));
    }

    #[test]
    fn test_set_size() {
        let mut b = Box2D {
            min: point2(1.0, 2.0),
            max: point2(3.0, 4.0),
        };
        b.set_size(size2(5.0, 6.0));

        assert_eq!(b.min, point2(1.0, 2.0));
        assert_eq!(b.size(), size2(5.0, 6.0));
    }
}