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
|
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef MOZILLA_GFX_COORD_H_
#define MOZILLA_GFX_COORD_H_
#include "mozilla/Attributes.h"
#include "mozilla/TypeTraits.h" // For IsSame
#include "Types.h"
#include "BaseCoord.h"
#include <cmath>
namespace mozilla {
template <typename> struct IsPixel;
namespace gfx {
template <class units> struct IntCoordTyped;
template <class units, class F = Float> struct CoordTyped;
// CommonType<coord, primitive> is a metafunction that returns the type of the
// result of an arithmetic operation on the underlying type of a strongly-typed
// coordinate type 'coord', and a primitive type 'primitive'. C++ rules for
// arithmetic conversions are designed to avoid losing information - for
// example, the result of adding an int and a float is a float - and we want
// the same behaviour when mixing our coordinate types with primitive types.
// We get C++ to compute the desired result type using 'decltype'.
template <class coord, class primitive>
struct CommonType;
template <class units, class primitive>
struct CommonType<IntCoordTyped<units>, primitive> {
typedef decltype(int32_t() + primitive()) type;
};
template <class units, class F, class primitive>
struct CommonType<CoordTyped<units, F>, primitive> {
typedef decltype(F() + primitive()) type;
};
// This is a base class that provides mixed-type operator overloads between
// a strongly-typed Coord and a primitive value. It is needed to avoid
// ambiguities at mixed-type call sites, because Coord classes are implicitly
// convertible to their underlying value type. As we transition more of our code
// to strongly-typed classes, we may be able to remove some or all of these
// overloads.
template <bool B, class coord, class primitive>
struct CoordOperatorsHelper {
// Using SFINAE (Substitution Failure Is Not An Error) to suppress redundant
// operators
};
template <class coord, class primitive>
struct CoordOperatorsHelper<true, coord, primitive> {
friend bool operator==(coord aA, primitive aB) {
return aA.value == aB;
}
friend bool operator==(primitive aA, coord aB) {
return aA == aB.value;
}
friend bool operator!=(coord aA, primitive aB) {
return aA.value != aB;
}
friend bool operator!=(primitive aA, coord aB) {
return aA != aB.value;
}
typedef typename CommonType<coord, primitive>::type result_type;
friend result_type operator+(coord aA, primitive aB) {
return aA.value + aB;
}
friend result_type operator+(primitive aA, coord aB) {
return aA + aB.value;
}
friend result_type operator-(coord aA, primitive aB) {
return aA.value - aB;
}
friend result_type operator-(primitive aA, coord aB) {
return aA - aB.value;
}
friend result_type operator*(coord aCoord, primitive aScale) {
return aCoord.value * aScale;
}
friend result_type operator*(primitive aScale, coord aCoord) {
return aScale * aCoord.value;
}
friend result_type operator/(coord aCoord, primitive aScale) {
return aCoord.value / aScale;
}
// 'scale / coord' is intentionally omitted because it doesn't make sense.
};
// Note: 'IntCoordTyped<units>' and 'CoordTyped<units>' do not derive from
// 'units' to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61959.
template<class units>
struct IntCoordTyped :
public BaseCoord< int32_t, IntCoordTyped<units> >,
public CoordOperatorsHelper< true, IntCoordTyped<units>, float >,
public CoordOperatorsHelper< true, IntCoordTyped<units>, double > {
static_assert(IsPixel<units>::value,
"'units' must be a coordinate system tag");
typedef BaseCoord< int32_t, IntCoordTyped<units> > Super;
constexpr IntCoordTyped() : Super() {}
constexpr MOZ_IMPLICIT IntCoordTyped(int32_t aValue) : Super(aValue) {}
};
template<class units, class F>
struct CoordTyped :
public BaseCoord< F, CoordTyped<units, F> >,
public CoordOperatorsHelper< !IsSame<F, int32_t>::value, CoordTyped<units, F>, int32_t >,
public CoordOperatorsHelper< !IsSame<F, uint32_t>::value, CoordTyped<units, F>, uint32_t >,
public CoordOperatorsHelper< !IsSame<F, double>::value, CoordTyped<units, F>, double >,
public CoordOperatorsHelper< !IsSame<F, float>::value, CoordTyped<units, F>, float > {
static_assert(IsPixel<units>::value,
"'units' must be a coordinate system tag");
typedef BaseCoord< F, CoordTyped<units, F> > Super;
constexpr CoordTyped() : Super() {}
constexpr MOZ_IMPLICIT CoordTyped(F aValue) : Super(aValue) {}
explicit constexpr CoordTyped(const IntCoordTyped<units>& aCoord) : Super(F(aCoord.value)) {}
void Round() {
this->value = floor(this->value + 0.5);
}
void Truncate() {
this->value = int32_t(this->value);
}
IntCoordTyped<units> Rounded() const {
return IntCoordTyped<units>(int32_t(floor(this->value + 0.5)));
}
IntCoordTyped<units> Truncated() const {
return IntCoordTyped<units>(int32_t(this->value));
}
};
} // namespace gfx
} // namespace mozilla
#endif /* MOZILLA_GFX_COORD_H_ */
|
