What's the best way to “round” a Color object to the nearest Color Constant?

Question

I will be retrieving the exact color of a pixel and would like to relate that exact color to a constant like Color.blue. Is there an easy way to \"round\" to the n

Answer 1

Probably the best way would be to loop over every constant, and comparing their respective RGB channels (getRed, getGreen, getBlue). Keep track of the one that is closest.

Color color = new Color(...);
Color[] constantColors = new Color[] { Color.black, Color.blue, Color.cyan, Color.darkGray, Color.gray, Color.green, Color.lightGray, Color.magenta, Color.orange, Color.pink, Color.red, Color.white, Color.yellow };
Color nearestColor = null;
Integer nearestDistance = new Integer(Integer.MAX_VALUE);

for (Color constantColor : constantColors) {
    if (nearestDistance > Math.sqrt(
            Math.pow(color.getRed() - constantColor.getRed(), 2)
            - Math.pow(color.getGreen() - constantColor.getGreen(), 2)
            - Math.pow(color.getBlue() - constantColor.getBlue(), 2)
        )
    ) {
        nearestColor = color;
    }
}

No, you can't add color constants to the class, but you can create a class of your own to hold constants.

class MyColors {
    public static final Color heliotrope = new Color(...);
}

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Edit: added difference algorithm, thanks to @Ted's link.