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关于.net：如何在Asp.net中使用HSL

2023-04-11 17:16:00

how to use HSL in Asp.net

.net中使用哪些工具处理HSL颜色？

颜色结构提供三种方法：GetHue，GetSaturation和GetBrightness。

鲍勃·鲍威尔(Bob Powell)在几年前就此发表了一篇有趣的文章。

怪异的历史记录-" HSL"(及相关的" HSV")是源自70年代施乐公司帕洛阿尔托研究中心(PARC)的众多事物之一，由Alvy Ray Smith提供。

这个ColorRGB类提供了获取和设置HSL的方法，以及与System.Drawing.Color之间的隐式转换。它基于GeekMonkey.com的一个出色示例。

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using System;
using System.Drawing;

namespace RMA.Drawing
{
public class ColorRGB
{
public byte R;
public byte G;
public byte B;
public byte A;

public ColorRGB()
{
R = 255;
G = 255;
B = 255;
A = 255;
}

public ColorRGB(Color value)
{
this.R = value.R;
this.G = value.G;
this.B = value.B;
this.A = value.A;
}

public static implicit operator Color(ColorRGB rgb)
{
Color c = Color.FromArgb(rgb.A, rgb.R, rgb.G, rgb.B);
return c;
}

public static explicit operator ColorRGB(Color c)
{
return new ColorRGB(c);
}

// Given H,S,L in range of 0-1
// Returns a Color (RGB struct) in range of 0-255
public static ColorRGB FromHSL(double H, double S, double L)
{
return FromHSLA(H, S, L, 1.0);
}

// Given H,S,L,A in range of 0-1
// Returns a Color (RGB struct) in range of 0-255
public static ColorRGB FromHSLA(double H, double S, double L, double A)
{
double v;
double r, g, b;

if (A > 1.0)
A = 1.0;

r = L; // default to gray
g = L;
b = L;
v = (L <= 0.5) ? (L * (1.0 + S)) : (L + S - L * S);

if (v > 0)
{
double m;
double sv;
int sextant;
double fract, vsf, mid1, mid2;

m = L + L - v;
sv = (v - m) / v;
H *= 6.0;
sextant = (int)H;
fract = H - sextant;
vsf = v * sv * fract;
mid1 = m + vsf;
mid2 = v - vsf;

switch (sextant)
{
case 0:
r = v;
g = mid1;
b = m;
break;

case 1:
r = mid2;
g = v;
b = m;
break;

case 2:
r = m;
g = v;
b = mid1;
break;

case 3:
r = m;
g = mid2;
b = v;
break;

case 4:
r = mid1;
g = m;
b = v;
break;

case 5:
r = v;
g = m;
b = mid2;
break;
}
}

ColorRGB rgb = new ColorRGB();
rgb.R = Convert.ToByte(r * 255.0f);
rgb.G = Convert.ToByte(g * 255.0f);
rgb.B = Convert.ToByte(b * 255.0f);
rgb.A = Convert.ToByte(A * 255.0f);
return rgb;
}

// Hue in range from 0.0 to 1.0
public float H
{
get
{
// Use System.Drawing.Color.GetHue, but divide by 360.0F
// because System.Drawing.Color returns hue in degrees (0 - 360)
// rather than a number between 0 and 1.
return ((Color)this).GetHue() / 360.0F;
}
}

// Saturation in range 0.0 - 1.0
public float S
{
get
{
return ((Color)this).GetSaturation();
}
}

// Lightness in range 0.0 - 1.0
public float L
{
get
{
return ((Color)this).GetBrightness();
}
}
}
}

除了secretGeek的答案之外，要从HSL值获得颜色(反之亦然)，还可以使用以下本机函数调用(Visual Basic中的示例代码)：

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Public Declare Sub ColorRGBToHLS Lib"shlwapi.dll" _
(ByVal clrRGB As UInteger, _
ByRef pwHue As Short, _
ByRef pwLuminance As Short, _
ByRef pwSaturation As Short)
Public Declare Function ColorHLSToRGB Lib"shlwapi.dll" _
(ByVal wHue As Short, _
ByVal wLuminance As Short, _
ByVal wSaturation As Short) As UInteger

(在传递/接收颜色参数/结果时使用ColorTranslator.ToWin32和ColorTranslator.FromWin32)

工具结构方法历史记录