根据用户选的背景色，自动匹配一个前景色
最近又写代码啦，感觉挺好。
ok，一个页面，说要玩自定义，懒得让美工一套一套模版设计了，直接让用户自己调颜色了。搜了下，发现jquery miniColors效果不错。然后又想让用户选好背景再选前景比较烦，可能配出来又比较丑，那就自动根据用户选的背景色匹配一个同色系前景色吧。
如果直接rgb来算，比较麻烦，但是颜色有另一种表示方法：HSL，最三个参数L是亮度，如果用户选的是个暗色，那把L调高就可以得到一个可以反衫的亮色，如果用户选的是个亮色，那把L调低就可以得到一个暗色来对比。基于这个思路，找一个HSL<->RGB的算法很容易，比如 http://mjijackson.com/2008/02/rgb-to-hsl-and-rgb-to-hsv-color-model-conversion-algorithms-in-javascript
然后一小段代码就可以 ：
function getContrastColor(rgb) {
var hsl = rgbToHsl(rgb.r, rgb.g, rgb.b);
hsl[2] = (hsl[2] + 0.5) % 1.0;
var new_rgb = hslToRgb.apply(this, hsl);
return ['rgb(',parseInt(new_rgb[0]),',',parseInt(new_rgb[1]),',',parseInt(new_rgb[2]),')'].join('');
}
var hsl = rgbToHsl(rgb.r, rgb.g, rgb.b);
hsl[2] = (hsl[2] + 0.5) % 1.0;
var new_rgb = hslToRgb.apply(this, hsl);
return ['rgb(',parseInt(new_rgb[0]),',',parseInt(new_rgb[1]),',',parseInt(new_rgb[2]),')'].join('');
}
//
完整示例如下：
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title></title>
<link rel="stylesheet" type="text/css" href="http://labs.abeautifulsite.net/jquery-miniColors/jquery.miniColors.css"></link>
<style type="text/css">
#stage {
margin-left:300px;
width:200px;
height:100px;
font-size:32px;
}
</style>
<script src="Scripts/jquery-1.8.2.js"></script>
<script src="http://labs.abeautifulsite.net/jquery-miniColors/jquery.miniColors.js"></script>
<script src="Scripts/HSL2RGB.js"></script>
<script type="text/javascript">
function getContrastColor(rgb) {
var hsl = rgbToHsl(rgb.r, rgb.g, rgb.b);
hsl[2] = (hsl[2] + 0.5) % 1.0;
var new_rgb = hslToRgb.apply(this, hsl);
return ['rgb(',parseInt(new_rgb[0]),',',parseInt(new_rgb[1]),',',parseInt(new_rgb[2]),')'].join('');
}
function colorHandler(hex, rgb) {
$('#stage').css({ 'color': hex, 'backgroundColor': getContrastColor(rgb) });
}
$(function () {
$('.color-picker').miniColors({
change: colorHandler,
open: colorHandler,
close: colorHandler
});
});
</script>
</head>
<body>
<input type="text" name="color1" class="color-picker" size="7" autocomplete="on" value="#fff" />
<div id="stage">
welcome!
</div>
</body>
</html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title></title>
<link rel="stylesheet" type="text/css" href="http://labs.abeautifulsite.net/jquery-miniColors/jquery.miniColors.css"></link>
<style type="text/css">
#stage {
margin-left:300px;
width:200px;
height:100px;
font-size:32px;
}
</style>
<script src="Scripts/jquery-1.8.2.js"></script>
<script src="http://labs.abeautifulsite.net/jquery-miniColors/jquery.miniColors.js"></script>
<script src="Scripts/HSL2RGB.js"></script>
<script type="text/javascript">
function getContrastColor(rgb) {
var hsl = rgbToHsl(rgb.r, rgb.g, rgb.b);
hsl[2] = (hsl[2] + 0.5) % 1.0;
var new_rgb = hslToRgb.apply(this, hsl);
return ['rgb(',parseInt(new_rgb[0]),',',parseInt(new_rgb[1]),',',parseInt(new_rgb[2]),')'].join('');
}
function colorHandler(hex, rgb) {
$('#stage').css({ 'color': hex, 'backgroundColor': getContrastColor(rgb) });
}
$(function () {
$('.color-picker').miniColors({
change: colorHandler,
open: colorHandler,
close: colorHandler
});
});
</script>
</head>
<body>
<input type="text" name="color1" class="color-picker" size="7" autocomplete="on" value="#fff" />
<div id="stage">
welcome!
</div>
</body>
</html>
HSL2RGB.js ：
View Code 
/**
* Converts an RGB color value to HSL. Conversion formula
* adapted from http://en.wikipedia.org/wiki/HSL_color_space.
* Assumes r, g, and b are contained in the set [0, 255] and
* returns h, s, and l in the set [0, 1].
*
* @param Number r The red color value
* @param Number g The green color value
* @param Number b The blue color value
* @return Array The HSL representation
*/
function rgbToHsl(r, g, b) {
r /= 255, g /= 255, b /= 255;
var max = Math.max(r, g, b), min = Math.min(r, g, b);
var h, s, l = (max + min) / 2;
if (max == min) {
h = s = 0; // achromatic
} else {
var d = max - min;
s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
switch (max) {
case r: h = (g - b) / d + (g < b ? 6 : 0); break;
case g: h = (b - r) / d + 2; break;
case b: h = (r - g) / d + 4; break;
}
h /= 6;
}
return [h, s, l];
}
/**
* Converts an HSL color value to RGB. Conversion formula
* adapted from http://en.wikipedia.org/wiki/HSL_color_space.
* Assumes h, s, and l are contained in the set [0, 1] and
* returns r, g, and b in the set [0, 255].
*
* @param Number h The hue
* @param Number s The saturation
* @param Number l The lightness
* @return Array The RGB representation
*/
function hslToRgb(h, s, l) {
var r, g, b;
if (s == 0) {
r = g = b = l; // achromatic
} else {
function hue2rgb(p, q, t) {
if (t < 0) t += 1;
if (t > 1) t -= 1;
if (t < 1 / 6) return p + (q - p) * 6 * t;
if (t < 1 / 2) return q;
if (t < 2 / 3) return p + (q - p) * (2 / 3 - t) * 6;
return p;
}
var q = l < 0.5 ? l * (1 + s) : l + s - l * s;
var p = 2 * l - q;
r = hue2rgb(p, q, h + 1 / 3);
g = hue2rgb(p, q, h);
b = hue2rgb(p, q, h - 1 / 3);
}
return [r * 255, g * 255, b * 255];
}
/**
* Converts an RGB color value to HSV. Conversion formula
* adapted from http://en.wikipedia.org/wiki/HSV_color_space.
* Assumes r, g, and b are contained in the set [0, 255] and
* returns h, s, and v in the set [0, 1].
*
* @param Number r The red color value
* @param Number g The green color value
* @param Number b The blue color value
* @return Array The HSV representation
*/
function rgbToHsv(r, g, b) {
r = r / 255, g = g / 255, b = b / 255;
var max = Math.max(r, g, b), min = Math.min(r, g, b);
var h, s, v = max;
var d = max - min;
s = max == 0 ? 0 : d / max;
if (max == min) {
h = 0; // achromatic
} else {
switch (max) {
case r: h = (g - b) / d + (g < b ? 6 : 0); break;
case g: h = (b - r) / d + 2; break;
case b: h = (r - g) / d + 4; break;
}
h /= 6;
}
return [h, s, v];
}
/**
* Converts an HSV color value to RGB. Conversion formula
* adapted from http://en.wikipedia.org/wiki/HSV_color_space.
* Assumes h, s, and v are contained in the set [0, 1] and
* returns r, g, and b in the set [0, 255].
*
* @param Number h The hue
* @param Number s The saturation
* @param Number v The value
* @return Array The RGB representation
*/
function hsvToRgb(h, s, v) {
var r, g, b;
var i = Math.floor(h * 6);
var f = h * 6 - i;
var p = v * (1 - s);
var q = v * (1 - f * s);
var t = v * (1 - (1 - f) * s);
switch (i % 6) {
case 0: r = v, g = t, b = p; break;
case 1: r = q, g = v, b = p; break;
case 2: r = p, g = v, b = t; break;
case 3: r = p, g = q, b = v; break;
case 4: r = t, g = p, b = v; break;
case 5: r = v, g = p, b = q; break;
}
return [r * 255, g * 255, b * 255];
}
* Converts an RGB color value to HSL. Conversion formula
* adapted from http://en.wikipedia.org/wiki/HSL_color_space.
* Assumes r, g, and b are contained in the set [0, 255] and
* returns h, s, and l in the set [0, 1].
*
* @param Number r The red color value
* @param Number g The green color value
* @param Number b The blue color value
* @return Array The HSL representation
*/
function rgbToHsl(r, g, b) {
r /= 255, g /= 255, b /= 255;
var max = Math.max(r, g, b), min = Math.min(r, g, b);
var h, s, l = (max + min) / 2;
if (max == min) {
h = s = 0; // achromatic
} else {
var d = max - min;
s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
switch (max) {
case r: h = (g - b) / d + (g < b ? 6 : 0); break;
case g: h = (b - r) / d + 2; break;
case b: h = (r - g) / d + 4; break;
}
h /= 6;
}
return [h, s, l];
}
/**
* Converts an HSL color value to RGB. Conversion formula
* adapted from http://en.wikipedia.org/wiki/HSL_color_space.
* Assumes h, s, and l are contained in the set [0, 1] and
* returns r, g, and b in the set [0, 255].
*
* @param Number h The hue
* @param Number s The saturation
* @param Number l The lightness
* @return Array The RGB representation
*/
function hslToRgb(h, s, l) {
var r, g, b;
if (s == 0) {
r = g = b = l; // achromatic
} else {
function hue2rgb(p, q, t) {
if (t < 0) t += 1;
if (t > 1) t -= 1;
if (t < 1 / 6) return p + (q - p) * 6 * t;
if (t < 1 / 2) return q;
if (t < 2 / 3) return p + (q - p) * (2 / 3 - t) * 6;
return p;
}
var q = l < 0.5 ? l * (1 + s) : l + s - l * s;
var p = 2 * l - q;
r = hue2rgb(p, q, h + 1 / 3);
g = hue2rgb(p, q, h);
b = hue2rgb(p, q, h - 1 / 3);
}
return [r * 255, g * 255, b * 255];
}
/**
* Converts an RGB color value to HSV. Conversion formula
* adapted from http://en.wikipedia.org/wiki/HSV_color_space.
* Assumes r, g, and b are contained in the set [0, 255] and
* returns h, s, and v in the set [0, 1].
*
* @param Number r The red color value
* @param Number g The green color value
* @param Number b The blue color value
* @return Array The HSV representation
*/
function rgbToHsv(r, g, b) {
r = r / 255, g = g / 255, b = b / 255;
var max = Math.max(r, g, b), min = Math.min(r, g, b);
var h, s, v = max;
var d = max - min;
s = max == 0 ? 0 : d / max;
if (max == min) {
h = 0; // achromatic
} else {
switch (max) {
case r: h = (g - b) / d + (g < b ? 6 : 0); break;
case g: h = (b - r) / d + 2; break;
case b: h = (r - g) / d + 4; break;
}
h /= 6;
}
return [h, s, v];
}
/**
* Converts an HSV color value to RGB. Conversion formula
* adapted from http://en.wikipedia.org/wiki/HSV_color_space.
* Assumes h, s, and v are contained in the set [0, 1] and
* returns r, g, and b in the set [0, 255].
*
* @param Number h The hue
* @param Number s The saturation
* @param Number v The value
* @return Array The RGB representation
*/
function hsvToRgb(h, s, v) {
var r, g, b;
var i = Math.floor(h * 6);
var f = h * 6 - i;
var p = v * (1 - s);
var q = v * (1 - f * s);
var t = v * (1 - (1 - f) * s);
switch (i % 6) {
case 0: r = v, g = t, b = p; break;
case 1: r = q, g = v, b = p; break;
case 2: r = p, g = v, b = t; break;
case 3: r = p, g = q, b = v; break;
case 4: r = t, g = p, b = v; break;
case 5: r = v, g = p, b = q; break;
}
return [r * 255, g * 255, b * 255];
}
