1 /* 2 * Copyright 2019 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #pragma once 18 19 #include <algorithm> 20 #include <cstdint> 21 #include <limits> 22 #include <type_traits> 23 #include <utility> 24 25 namespace android { 26 namespace ui { 27 28 // Forward declare a few things. 29 struct Size; 30 bool operator==(const Size& lhs, const Size& rhs); 31 32 /** 33 * A simple value type representing a two-dimensional size 34 */ 35 struct Size { 36 int32_t width; 37 int32_t height; 38 39 // Special values 40 static const Size INVALID; 41 static const Size EMPTY; 42 43 // ------------------------------------------------------------------------ 44 // Construction 45 // ------------------------------------------------------------------------ 46 SizeSize47 Size() : Size(INVALID) {} 48 template <typename T> SizeSize49 Size(T&& w, T&& h) 50 : width(Size::clamp<int32_t, T>(std::forward<T>(w))), 51 height(Size::clamp<int32_t, T>(std::forward<T>(h))) {} 52 53 // ------------------------------------------------------------------------ 54 // Accessors 55 // ------------------------------------------------------------------------ 56 getWidthSize57 int32_t getWidth() const { return width; } getHeightSize58 int32_t getHeight() const { return height; } 59 60 template <typename T> setWidthSize61 void setWidth(T&& v) { 62 width = Size::clamp<int32_t, T>(std::forward<T>(v)); 63 } 64 template <typename T> setHeightSize65 void setHeight(T&& v) { 66 height = Size::clamp<int32_t, T>(std::forward<T>(v)); 67 } 68 69 // ------------------------------------------------------------------------ 70 // Assignment 71 // ------------------------------------------------------------------------ 72 setSize73 void set(const Size& size) { *this = size; } 74 template <typename T> setSize75 void set(T&& w, T&& h) { 76 set(Size(std::forward<T>(w), std::forward<T>(h))); 77 } 78 79 // Sets the value to INVALID makeInvalidSize80 void makeInvalid() { set(INVALID); } 81 82 // Sets the value to EMPTY clearSize83 void clear() { set(EMPTY); } 84 85 // ------------------------------------------------------------------------ 86 // Semantic checks 87 // ------------------------------------------------------------------------ 88 89 // Valid means non-negative width and height isValidSize90 bool isValid() const { return width >= 0 && height >= 0; } 91 92 // Empty means zero width and height isEmptySize93 bool isEmpty() const { return *this == EMPTY; } 94 95 // ------------------------------------------------------------------------ 96 // Clamp Helpers 97 // ------------------------------------------------------------------------ 98 99 // Note: We use only features available in C++11 here for compatibility with 100 // external targets which include this file directly or indirectly and which 101 // themselves use C++11. 102 103 // C++11 compatible replacement for std::remove_cv_reference_t [C++20] 104 template <typename T> 105 using remove_cv_reference_t = 106 typename std::remove_cv<typename std::remove_reference<T>::type>::type; 107 108 // Takes a value of type FromType, and ensures it can be represented as a value of type ToType, 109 // clamping the input value to the output range if necessary. 110 template <typename ToType, typename FromType> clampSize111 static Size::remove_cv_reference_t<ToType> clamp( 112 typename std::enable_if< 113 std::numeric_limits<Size::remove_cv_reference_t<ToType>>::is_bounded && 114 std::numeric_limits<Size::remove_cv_reference_t<FromType>>::is_bounded, 115 FromType&&>::type v) { 116 static constexpr auto toHighest = std::numeric_limits<remove_cv_reference_t<ToType>>::max(); 117 static constexpr auto toLowest = 118 std::numeric_limits<remove_cv_reference_t<ToType>>::lowest(); 119 static constexpr auto fromHighest = 120 std::numeric_limits<remove_cv_reference_t<FromType>>::max(); 121 static constexpr auto fromLowest = 122 std::numeric_limits<remove_cv_reference_t<FromType>>::lowest(); 123 124 // A clamp is needed if the range of FromType is not a subset of the range of ToType 125 static constexpr bool isClampNeeded = (toLowest > fromLowest) || (toHighest < fromHighest); 126 127 // If a clamp is not needed, the conversion is just a trivial cast. 128 if (!isClampNeeded) { 129 return static_cast<ToType>(v); 130 } 131 132 // Otherwise we leverage implicit conversion to safely compare values of 133 // different types, to ensure we return a value clamped to the range of 134 // ToType. 135 return v < toLowest ? toLowest : (v > toHighest ? toHighest : static_cast<ToType>(v)); 136 } 137 }; 138 139 // ------------------------------------------------------------------------ 140 // Comparisons 141 // ------------------------------------------------------------------------ 142 143 inline bool operator==(const Size& lhs, const Size& rhs) { 144 return lhs.width == rhs.width && lhs.height == rhs.height; 145 } 146 147 inline bool operator!=(const Size& lhs, const Size& rhs) { 148 return !operator==(lhs, rhs); 149 } 150 151 inline bool operator<(const Size& lhs, const Size& rhs) { 152 // Orders by increasing width, then height. 153 if (lhs.width != rhs.width) return lhs.width < rhs.width; 154 return lhs.height < rhs.height; 155 } 156 157 } // namespace ui 158 } // namespace android 159