mirror of
https://github.com/LNH-team/pico-launcher.git
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133 lines
3.7 KiB
C++
133 lines
3.7 KiB
C++
/*
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* Copyright 2022 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef CPP_CAM_HCT_H_
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#define CPP_CAM_HCT_H_
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#include "material/utils/utils.h"
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namespace material_color_utilities {
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/**
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* HCT: hue, chroma, and tone.
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*
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* A color system built using CAM16 hue and chroma, and L* (lightness) from
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* the L*a*b* color space, providing a perceptually accurate
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* color measurement system that can also accurately render what colors
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* will appear as in different lighting environments.
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*
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* Using L* creates a link between the color system, contrast, and thus
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* accessibility. Contrast ratio depends on relative luminance, or Y in the XYZ
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* color space. L*, or perceptual luminance can be calculated from Y.
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*
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* Unlike Y, L* is linear to human perception, allowing trivial creation of
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* accurate color tones.
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*
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* Unlike contrast ratio, measuring contrast in L* is linear, and simple to
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* calculate. A difference of 40 in HCT tone guarantees a contrast ratio >= 3.0,
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* and a difference of 50 guarantees a contrast ratio >= 4.5.
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*/
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class Hct {
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public:
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/**
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* Creates an HCT color from hue, chroma, and tone.
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*
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* @param hue 0 <= hue < 360; invalid values are corrected.
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* @param chroma >= 0; the maximum value of chroma depends on the hue
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* and tone. May be lower than the requested chroma.
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* @param tone 0 <= tone <= 100; invalid values are corrected.
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* @return HCT representation of a color in default viewing conditions.
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*/
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Hct(double hue, double chroma, double tone);
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/**
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* Creates an HCT color from a color.
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*
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* @param argb ARGB representation of a color.
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* @return HCT representation of a color in default viewing conditions
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*/
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explicit Hct(Argb argb);
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/**
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* Returns the hue of the color.
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*
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* @return hue of the color, in degrees.
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*/
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double get_hue();
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/**
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* Returns the chroma of the color.
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*
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* @return chroma of the color.
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*/
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double get_chroma();
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/**
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* Returns the tone of the color.
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*
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* @return tone of the color, satisfying 0 <= tone <= 100.
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*/
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double get_tone();
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/**
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* Returns the color in ARGB format.
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*
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* @return an integer, representing the color in ARGB format.
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*/
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Argb ToInt();
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/**
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* Sets the hue of this color. Chroma may decrease because chroma has a
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* different maximum for any given hue and tone.
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*
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* @param new_hue 0 <= new_hue < 360; invalid values are corrected.
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*/
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void set_hue(double new_hue);
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/**
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* Sets the chroma of this color. Chroma may decrease because chroma has a
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* different maximum for any given hue and tone.
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*
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* @param new_chroma 0 <= new_chroma < ?
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*/
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void set_chroma(double new_chroma);
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/**
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* Sets the tone of this color. Chroma may decrease because chroma has a
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* different maximum for any given hue and tone.
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*
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* @param new_tone 0 <= new_tone <= 100; invalid valids are corrected.
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*/
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void set_tone(double new_tone);
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private:
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/**
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* Sets the Hct object to represent an sRGB color.
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*
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* @param argb the new color as an integer in ARGB format.
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*/
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void SetInternalState(Argb argb);
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double hue_ = 0.0;
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double chroma_ = 0.0;
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double tone_ = 0.0;
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Argb argb_ = 0;
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};
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} // namespace material_color_utilities
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#endif // CPP_CAM_HCT_H_
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