php 转换为 3 位十六进制颜色代码
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convert to 3-digit hex color code
提问by eozzy
I've been using 3-digit hex color values in CSS for a long time: #fff, #999, #069, etc. I can see how the repeating letters/numbers are merged to create a 3-digit hex color code, but I don't fully understand the pattern to be able to write a converter in PHP. Is there documentation for this?
我一直在 CSS 中使用 3 位十六进制颜色值很长时间：#fff、#999、#069等。我可以看到重复的字母/数字如何合并以创建 3 位十六进制颜色代码，但我不完全了解模式以便能够在 PHP 中编写转换器。有这方面的文件吗？
Edit:Oh, perhaps my question wasn't clear. I need to know how some of the 6-digit hex color values are converted to 3-digits. xxxxxx(ffffff) and xxyyzz(006699) – these are the only two patterns, correct?
编辑：哦，也许我的问题不清楚。我需要知道一些 6 位十六进制颜色值是如何转换为 3 位的。xxxxxx( ffffff) 和xxyyzz( 006699) – 这是仅有的两种模式，对吗？
回答by Greg
To convert a 3-character hex code into a 6 character one, you need to repeat each character:
要将 3 个字符的十六进制代码转换为 6 个字符的十六进制代码，您需要重复每个字符：
$hex = '#fff';
$hex6 = '#' . $hex[1] . $hex[1] . $hex[2] . $hex[2] . $hex[3] . $hex[3];
If you want to convert it to decimal you can use the hexdecfunction
如果要将其转换为十进制，可以使用该hexdec函数
回答by Kobi
3 digit CSS code is short for 6 digits": #06a; is #0066aa;
Each two digits represent a number from 0 to 255.
Converting these values to hex and back is all you need.
3 位 CSS 代码是 6 位数字的缩写”：#06a; is #0066aa;
每两位数字代表一个从 0 到 255 的数字。
将这些值转换为十六进制并返回即可。
回答by jensgram
#f0fis expanded to #ff00ffso basically you just need to calculate the value and the value times 16 for each character, e.g.:
#f0f扩展为#ff00ff因此基本上您只需要计算每个字符的值和值乘以 16，例如：
#f98: f = 15 => red = 15 + 15*16 = 255 etc.
#f98: f = 15 => 红色 = 15 + 15*16 = 255 等等。
回答by Dan Mecklenburg
function hexfix(str) {
var v, w;
v = parseInt(str, 16); // in rrggbb
if (str.length == 3) {
// nybble colors - fix to hex colors
// 0x00000rgb -> 0x000r0g0b
// 0x000r0g0b | 0x00r0g0b0 -> 0x00rrggbb
w = ((v & 0xF00) << 8) | ((v & 0x0F0) << 4) | (v & 0x00F);
v = w | (w << 4);
}
return v.toString(16).toUpperCase();
}
var hex1 = 'AABBCC',
hex2 = 'ABC';
document.body.appendChild(document.createTextNode(hex1+" becomes "+hexfix(hex1)+'. '));
document.body.appendChild(document.createTextNode(hex2+" becomes "+hexfix(hex2)+'. '));Something like this.
像这样的东西。
