Is there a way to sort Color elements in a list (c#)?

user_9047575 0
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The idea is that I have a sorting mechanism that sorts according to the red value (later I wanna build on so I can sort by green and blue value too). I am having trouble implementing this sorting mechanism.

I have a class called Colorbox which is basically a List<Color> but this way I can put a List<Color> in a List<Colorbox>.

What my mean goal is that I can order this Colorbox according to 1 color (red, blue, green) value. (e.g. so that most left value in the list has least red).

I tried implementing a toCompare override (don't know if this works in C# but I know in Java the compare too is called upon when you call sort() method).

This gives me a code like following:

public int CompareTo(object obj) {
    Color toCompare = (Color) obj;
    if (this.CompareTo(toCompare) == 1)
    {
        return 1;
    }
    else 
    {
        return 0;
    }
}

but I don't see how I can implement my sort by color there or sort in general. Do I have to write an extra sort() to override the original.

I don't really have an idea what this sort code should do. Does it order value by value until it can go over the list and nothing is changed? or is this a way too long approach for this idea?

Underneath I give the general code of the class:

internal class Colorbox
{
    private List<Color> box = new List<Color>();
    int colorPicker = 0;
    public Colorbox(List<Color> colorList)
    {
        this.box = colorList;
    }
}

I hope someone can help explain what I should do or in which direction I should look to solve this problem.

Thanks a lot already and ask anything if I haven't been clear.

list sorting class c#
2 Answers

I believe you want the IComparer<T> interface to compare your Color types. Here is a sample using LinqPad. The RedColorComparer implementation will sort your Colors based on how much red they have DESCENDING, which is what it sounds like you want. Note the use of it with the Array.Sort line.

void Main()
{
    var colors = new Color[] { Color.Red, Color.Blue, Color.Gray };
    Array.Sort(colors, new RedColorComparer());
    colors.Dump();
}

public class RedColorComparer : IComparer<Color>
{
    public int Compare(Color a, Color b)
    {
        if (a.R < b.R)
            return 1;
        else if (a.R == b.R)
            return 0;
        else 
            return -1;
    }
}

And the results are like so:

enter image description here

user_2338100

You can get byte from Color Struct. For example, 

Color slateBlue = Color.FromName("SlateBlue");
byte g = slateBlue.G;
byte b = slateBlue.B;
byte r = slateBlue.R;
byte a = slateBlue.A;
string text = String.Format("Slate Blue has these ARGB values: Alpha:{0}, " +
    "red:{1}, green: {2}, blue {3}", new object[] { a, r, g, b });

and then try to order these byte implement ICompare

public class SortColorByRed : IComparer<Color>
{
    public int Compare(Color x, Color y)
    {
        if (x == null || y == null)
        {
            return 0;
        }
        return x.R.CompareTo(y.R);
    }
}

and then use it in Sort by passing Comparison

var color1 = new Color();
var color2 = new Color();
List<Color> list = new List<Color>(){color1,color2};
SortColorByRed sortByRed = new SortColorByRed(); 
list.Sort(sortByRed);
user_81724900
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