Convert string to Color in C#

问题:

I am encountering a problem which is how do I convert input strings like "RED" to the actual Color type Color.Red in C#. Is there a good way to do this?

I could think of using a switch statement and cases statement for each color type but I don't think that is clever enough.

回答1:

 Color red = Color.FromName("Red");   

The MSDN doesn't say one way or another, so there's a good chance that it is case-sensitive. (UPDATE: Apparently, it is not.)

As far as I can tell, ColorTranslator.FromHtml is also.

If Color.FromName cannot find a match, it returns new Color(0,0,0);

If ColorTranslator.FromHtml cannot find a match, it throws an exception.

UPDATE:

Since you're using Microsoft.Xna.Framework.Graphics.Color, this gets a bit tricky:

using XColor = Microsoft.Xna.Framework.Graphics.Color;
using CColor = System.Drawing.Color;

 CColor clrColor = CColor.FromName("Red"); 
 XColor xColor = new XColor(clrColor.R, clrColor.G, clrColor.B, clrColor.A);

回答2:

System.Drawing.Color myColor = System.Drawing.ColorTranslator.FromHtml("Red");

(Use my method if you want to accept HTML-style hex colors.)

回答3:

(It would really have been nice if you'd mentioned which Color type you were interested in to start with...)

One simple way of doing this is to just build up a dictionary via reflection:

public static class Colors
{
    private static readonly Dictionary<string, Color> dictionary =
        typeof(Color).GetProperties(BindingFlags.Public | 
                                    BindingFlags.Static)
                     .Where(prop => prop.PropertyType == typeof(Color))
                     .ToDictionary(prop => prop.Name,
                                   prop => (Color) prop.GetValue(null, null)));

    public static Color FromName(string name)
    {
        // Adjust behaviour for lookup failure etc
        return dictionary[name];
    }
}

That will be relatively slow for the first lookup (while it uses reflection to find all the properties) but should be very quick after that.

If you want it to be case-insensitive, you can pass in something like StringComparer.OrdinalIgnoreCase as an extra argument in the ToDictionary call. You can easily add TryParse etc methods should you wish.

Of course, if you only need this in one place, don't bother with a separate class etc :)

回答4:

Since the OP mentioned in a comment that he's using Microsoft.Xna.Framework.Graphics.Color rather than System.Drawing.Color you can first create a System.Drawing.Color then convert it to a Microsoft.Xna.Framework.Graphics.Color

public static Color FromName(string colorName)
{
    System.Drawing.Color systemColor = System.Drawing.Color.FromName(colorName);   
    return new Color(systemColor.R, systemColor.G, systemColor.B, systemColor.A); //Here Color is Microsoft.Xna.Framework.Graphics.Color
}

回答5:

It depends on what you're looking for, if you need System.Windows.Media.Color (like in WPF) it's very easy:

System.Windows.Media.Color color = (Color)System.Windows.Media.ColorConverter.ConvertFromString("Red");//or hexadecimal color, e.g. #131A84

回答6:

For transferring colors via xml-strings I've found out:

Color x = Color.Red; // for example
String s = x.ToArgb().ToString()
... to/from xml ...
Int32 argb = Convert.ToInt32(s);
Color red = Color.FromArgb(argb);

回答7:

This worked nicely for my needs ;) Hope someone can use it....

    public static Color FromName(String name)
    {
        var color_props= typeof(Colors).GetProperties();
        foreach (var c in color_props)
            if (name.Equals(c.Name, StringComparison.OrdinalIgnoreCase))
                return (Color)c.GetValue(new Color(), null);
        return Colors.Transparent;
    }

回答8:

The simplest way:

string input = null;
Color color = Color.White;

TextBoxText_Changed(object sender, EventsArgs e)
{
   input = TextBox.Text;
}

Button_Click(object sender, EventsArgs e)
{
   color = Color.FromName(input)
}

回答9:

I've used something like this before:

        public static T CreateFromString<T>(string stringToCreateFrom) {

        T output = Activator.CreateInstance<T>();

        if (!output.GetType().IsEnum)
            throw new IllegalTypeException();

        try {
            output = (T) Enum.Parse(typeof (T), stringToCreateFrom, true);
        }
        catch (Exception ex) {
            string error = "Cannot parse '" + stringToCreateFrom + "' to enum '" + typeof (T).FullName + "'";
            _logger.Error(error, ex);
            throw new IllegalArgumentException(error, ex);
        }

        return output;
    }