【代码片段】取最接近的Web-Safe Color

作者: RayLinn

最近的项目里需要从索引颜色里取最接近的颜色，用下面的代码实现之：

[code]
public static Color ScanNearestColor(Color color)
{
int leastDistance = int.MaxValue;
int red = color.R;
int green = color.G;
int blue = color.B;
byte colorIndex = 255;
Color[] _colors = GetColorPalette();
for (int index = 0; index < _colors.Length; index++)
{
// Lookup the color from the palette
Color paletteColor = _colors[index];

// Compute the distance from our source color to the palette color
int redDistance = paletteColor.R - red;
int greenDistance = paletteColor.G - green;
int blueDistance = paletteColor.B - blue;

int distance = (redDistance * redDistance) +
(greenDistance * greenDistance) +
(blueDistance * blueDistance);

// If the color is closer than any other found so far, use it
if (distance < leastDistance)
{
colorIndex = (byte)index;
leastDistance = distance;

// And if it's an exact match, exit the loop
if (0 == distance)
break;
}
}
return _colors[colorIndex];
}
[/code]

代码里的GetColorPalette返回索引颜色表，比如下面是生成Web安全色的颜色表：
[code]
private static Color[] GetWebSafeColorPalette()
{
Color[] aSafeCols = new Color[216];
int rValue, gValue, bValue;
int iPointer = 0;
for (rValue = 0; rValue <= 255; rValue += 51)
{
for (gValue = 0; gValue <= 255; gValue += 51)
{
for (bValue = 0; bValue <= 255; bValue += 51)
{
aSafeCols[iPointer] = Color.FromRgb((byte)rValue,(byte)gValue,(byte)bValue);
iPointer += 1;
}
}
}
[/code]

基本最后完成的是个基于Visual studio的CSS编辑器，配上上个项目里为CSS的颜色定义添加相应颜色的下划线，这样的CSS编辑器相当不错了，如果要完美一点，还可以加上图片预览的功能。

[img]http://dl.iteye.com/upload/attachment/281259/e0ee4dd2-60b5-306f-9d69-b00352f0dbd5.png[/img]

参考:
http://msdn.microsoft.com/en-us/library/aa479306.aspx