我想展示一些像这个例子的图片

填充颜色由数据库中颜色为十六进制的字段决定(例如:ClassX -> color: #66FFFF)。 现在,我想显示上面的数据与所选的颜色填充(如上图),但我需要知道如果颜色是暗或光,所以我知道如果文字应该在白色或黑色。 有办法吗?谢谢大家


当前回答

下面是我基于Mark的惊人回答编写的Java Swing代码:

public static Color getColorBasedOnBackground(Color background, Color darkColor, Color lightColor) {
    // Calculate foreground color based on background (based on https://stackoverflow.com/a/3943023/)
    Color color;
    double[] cL = new double[3];
    double[] colorRGB = new double[] {background.getRed(), background.getGreen(), background.getBlue()};

    for (int i = 0; i < colorRGB.length; i++)
        cL[i] = (colorRGB[i] / 255.0 <= 0.03928) ? colorRGB[i] / 255.0 / 12.92 :
                Math.pow(((colorRGB[i] / 255.0 + 0.055) / 1.055), 2.4);

    double L = 0.2126 * cL[0] + 0.7152 * cL[1] + 0.0722 * cL[2];
    color = (L > Math.sqrt(1.05 * 0.05) - 0.05) ? darkColor : lightColor;

    return color;
}

其他回答

从hex到black或white:

function hexToRgb(hex) {
  var result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
  return result
    ? [
        parseInt(result[1], 16),
        parseInt(result[2], 16),
        parseInt(result[3], 16)
      ]
    : [0, 0, 0];
}

function lum(hex) {
  var rgb = hexToRgb(hex)
  var lrgb = [];
  rgb.forEach(function(c) {
    c = c / 255.0;
    if (c <= 0.03928) {
      c = c / 12.92;
    } else {
      c = Math.pow((c + 0.055) / 1.055, 2.4);
    }
    lrgb.push(c);
  });
  var lum = 0.2126 * lrgb[0] + 0.7152 * lrgb[1] + 0.0722 * lrgb[2];
  return lum > 0.179 ? "#000000" : "#ffffff";
}

LESS有一个很好的对比度()函数,对我来说效果很好,请参阅http://lesscss.org/functions/#color-operations-contrast

“在两种颜色中选择一种颜色与另一种颜色形成最大的对比。 这对于确保颜色在背景下是可读的很有用,这对于可访问性遵从也很有用。此函数的工作方式与Compass for SASS中的对比函数相同。根据WCAG 2.0,颜色是用伽马校正的亮度值来比较的,而不是它们的亮度。”

例子:

p {
    a: contrast(#bbbbbb);
    b: contrast(#222222, #101010);
    c: contrast(#222222, #101010, #dddddd);
    d: contrast(hsl(90, 100%, 50%), #000000, #ffffff, 30%);
    e: contrast(hsl(90, 100%, 50%), #000000, #ffffff, 80%);
}

输出:

p {
    a: #000000 // black
    b: #ffffff // white
    c: #dddddd
    d: #000000 // black
    e: #ffffff // white
}

以下是我用Java编写的Android解决方案:

// Put this method in whichever class you deem appropriate
// static or non-static, up to you.
public static int getContrastColor(int colorIntValue) {
    int red = Color.red(colorIntValue);
    int green = Color.green(colorIntValue);
    int blue = Color.blue(colorIntValue);
    double lum = (((0.299 * red) + ((0.587 * green) + (0.114 * blue))));
    return lum > 186 ? 0xFF000000 : 0xFFFFFFFF;
}

// Usage
// If Color is represented as HEX code:
String colorHex = "#484588";
int color = Color.parseColor(colorHex);

// Or if color is Integer:
int color = 0xFF484588;

// Get White (0xFFFFFFFF) or Black (0xFF000000)
int contrastColor = WhateverClass.getContrastColor(color);

这是马克·兰森的答案的R版本,只使用R基。

hex_bw <- function(hex_code) {

  myrgb <- as.integer(col2rgb(hex_code))

  rgb_conv <- lapply(myrgb, function(x) {
    i <- x / 255
    if (i <= 0.03928) {
      i <- i / 12.92
    } else {
      i <- ((i + 0.055) / 1.055) ^ 2.4
    }
    return(i)
  })

 rgb_calc <- (0.2126*rgb_conv[[1]]) + (0.7152*rgb_conv[[2]]) + (0.0722*rgb_conv[[3]])

 if (rgb_calc > 0.179) return("#000000") else return("#ffffff")

}

> hex_bw("#8FBC8F")
[1] "#000000"
> hex_bw("#7fa5e3")
[1] "#000000"
> hex_bw("#0054de")
[1] "#ffffff"
> hex_bw("#2064d4")
[1] "#ffffff"
> hex_bw("#5387db")
[1] "#000000"

根据来自链接的不同输入,使前景颜色黑色或白色取决于背景和这个线程,我为颜色做了一个扩展类,为您提供所需的对比色。

代码如下:

 public static class ColorExtension
{       
    public static int PerceivedBrightness(this Color c)
    {
        return (int)Math.Sqrt(
        c.R * c.R * .299 +
        c.G * c.G * .587 +
        c.B * c.B * .114);
    }
    public static Color ContrastColor(this Color iColor, Color darkColor,Color lightColor)
    {
        //  Counting the perceptive luminance (aka luma) - human eye favors green color... 
        double luma = (iColor.PerceivedBrightness() / 255);

        // Return black for bright colors, white for dark colors
        return luma > 0.5 ? darkColor : lightColor;
    }
    public static Color ContrastColor(this Color iColor) => iColor.ContrastColor(Color.Black);
    public static Color ContrastColor(this Color iColor, Color darkColor) => iColor.ContrastColor(darkColor, Color.White);
    // Converts a given Color to gray
    public static Color ToGray(this Color input)
    {
        int g = (int)(input.R * .299) + (int)(input.G * .587) + (int)(input.B * .114);
        return Color.FromArgb(input.A, g, g, g);
    }
}