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Diffstat (limited to 'services/surfaceflinger/Fps.h')
| -rw-r--r-- | services/surfaceflinger/Fps.h | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/services/surfaceflinger/Fps.h b/services/surfaceflinger/Fps.h new file mode 100644 index 0000000000..e9f06e5519 --- /dev/null +++ b/services/surfaceflinger/Fps.h @@ -0,0 +1,112 @@ +/* + * Copyright (C) 2020 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#pragma once + +#include <cmath> +#include <ostream> +#include <string> + +#include <android-base/stringprintf.h> +#include <utils/Timers.h> + +namespace android { + +// Value which represents "frames per second". This class is a wrapper around +// float, providing some useful utilities, such as comparisons with tolerance +// and converting between period duration and frequency. +class Fps { +public: + static constexpr Fps fromPeriodNsecs(nsecs_t period) { return Fps(1e9f / period, period); } + + Fps() = default; + explicit constexpr Fps(float fps) + : fps(fps), period(fps == 0.0f ? 0 : static_cast<nsecs_t>(1e9f / fps)) {} + + constexpr float getValue() const { return fps; } + + constexpr nsecs_t getPeriodNsecs() const { return period; } + + bool equalsWithMargin(const Fps& other) const { return std::abs(fps - other.fps) < kMargin; } + + // DO NOT use for std::sort. Instead use comparesLess(). + bool lessThanWithMargin(const Fps& other) const { return fps + kMargin < other.fps; } + + bool greaterThanWithMargin(const Fps& other) const { return fps > other.fps + kMargin; } + + bool lessThanOrEqualWithMargin(const Fps& other) const { return !greaterThanWithMargin(other); } + + bool greaterThanOrEqualWithMargin(const Fps& other) const { return !lessThanWithMargin(other); } + + bool isValid() const { return fps > 0.0f; } + + int getIntValue() const { return static_cast<int>(std::round(fps)); } + + // Use this comparator for sorting. Using a comparator with margins can + // cause std::sort to crash. + inline static bool comparesLess(const Fps& left, const Fps& right) { + return left.fps < right.fps; + } + + // Compares two FPS with margin. + // Transitivity is not guaranteed, i.e. a==b and b==c doesn't imply a==c. + // DO NOT use with hash maps. Instead use EqualsInBuckets. + struct EqualsWithMargin { + bool operator()(const Fps& left, const Fps& right) const { + return left.equalsWithMargin(right); + } + }; + + // Equals comparator which can be used with hash maps. + // It's guaranteed that if two elements are equal, then their hashes are equal. + struct EqualsInBuckets { + bool operator()(const Fps& left, const Fps& right) const { + return left.getBucket() == right.getBucket(); + } + }; + + inline friend std::string to_string(const Fps& fps) { + return base::StringPrintf("%.2ffps", fps.fps); + } + + inline friend std::ostream& operator<<(std::ostream& os, const Fps& fps) { + return os << to_string(fps); + } + +private: + friend std::hash<android::Fps>; + + constexpr Fps(float fps, nsecs_t period) : fps(fps), period(period) {} + + float getBucket() const { return std::round(fps / kMargin); } + + static constexpr float kMargin = 0.001f; + float fps = 0; + nsecs_t period = 0; +}; + +static_assert(std::is_trivially_copyable_v<Fps>); + +} // namespace android + +namespace std { +template <> +struct hash<android::Fps> { + std::size_t operator()(const android::Fps& fps) const { + return std::hash<float>()(fps.getBucket()); + } +}; +} // namespace std
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