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Choose a random color other than certain colors.

I am currently using this code:

Random randomColor = new Random();
KnownColor[] names = (KnownColor[])Enum.GetValues(typeof(KnownColor));
KnownColor randomColorName = names[randomColor.Next(names.Length)];
Color RandomColor = Color.FromKnownColor(randomColorName);
this.BackColor = RandomColor;

I use this to create a random color and set it to my background, but I don't want it to go black.

Is there a way to remove black from possible random colors?

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3 answers


Option 1: Just use the list delete method:

List<KnownColor> namesList = new List<KnownColor>((KnownColor[])Enum.GetValues(typeof(KnownColor)));
namesList.Remove(KnownColor.Black);
KnownColor[] names = namesList.ToArray();

Option 2: Use only a list. They have much more control than arrays:



Random randomColor = new Random();
List<KnownColor> names = new List<KnownColor>((KnownColor[])Enum.GetValues(typeof(KnownColor)));
names.Remove(KnownColor.Black);
this.BackColor = Color.FromKnownColor(names[randomColor.Next(names.Count)]);

Addition: You can also remove all colors that are black but not called black (like ActiveCaption):

List<KnownColor> names = new List<KnownColor>((KnownColor[])Enum.GetValues(typeof(KnownColor)));
foreach (KnownColor i in names)
{
    if (Color.FromKnownColor(i).ToArgb() == Color.Black.ToArgb()) names.Remove(i);
}
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After that, how do I filter the colors (in this example, I remove the black and white colors from the color list) from the KnownColor and return a random color:



private Color getRandomColor()
    {
        Random randomGen = new Random();

        KnownColor[] names = (KnownColor[])Enum.GetValues(typeof(KnownColor));
        KnownColor[] badColors = { KnownColor.Black, KnownColor.White };

        IEnumerable<KnownColor> colors = names.Except(badColors);

        var okColors = colors.ToArray();
        KnownColor randomColorName = okColors[randomGen.Next(names.Length)];

        return Color.FromKnownColor(randomColorName);
    }
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The fastest and most efficient way to do it:

Random rng = new Random();
public Color randomColor()
{
    Color.FromArgb(rng.Next(-16777216, -1));
}

This will create a random color without black. It works because the color class stores the color as an integer, where black is 0.

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