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Accessing the full range of colors in procedural code

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Pencho Popadiyn
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Pencho Popadiyn
Joined Apr 30, 2008
Articles:   22
Comments:   97
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5 comments   /   posted on Aug 21, 2009
Tags:   colors , pencho-popadiyn
Categories:   General

This article is compatible with the latest version of Silverlight.


1. The problem

Download source code.

Have you ever wondered why the XAML parser recognizes the full palette of 141 colors (by name), but the Silverlight Colors class does not support the same full range of color names, for example, as WPF? I haven’t even noted that until the last week. In Silverlight in the XAML markup you can access all colors by name:

 Unfortunately, this is not valid if you try the same operation in the code behind file:

If you check in MSDN you will see that the Colors class allows you to access only 16 colors.

Probably the reason given for this is to reduce the Silverlight plug-in.

2. The solution

Of course we need to write a little bit of code in order to work-around the problem. The solution uses a very interesting programming technique, known as user-defined implicit conversion. For more info about the implicit conversion see the References section. But in a few words the implicit keyword in .NET allows you to declare an implicit user-defined type conversion from type X to type Y. For example see the next code snippet.

public class DemoClass
{
   public static implicit operator double( 
        DemoClass demoClass )
   {
       // Do here the logic about the conversion.
       return 0.0;
   }
}

This allows you an implicit conversion, without being specified explicit casts in the source code. What I mean is that you can do the following thing:

DemoClass demoClass = new DemoClass();
double xyz = demoClass;

By removing unnecessary casts, implicit conversions can improve the source code readability. However it is too good to last. Implicit conversions can occur without the programmer’s specifying them, that’s why care must be taken to prevent unpleasant surprises.

Let’s back again in our case. First you need to create a new class.

public sealed class ColorExtension
{
    private readonly uint value;
 
    private ColorExtension()
    {
    }
 
    private ColorExtension( uint color )
    {
        this.value = color;
    }
}

Second you need to add all colors recognized by the XAML parser. You can see them here.

public static readonly ColorExtension AliceBlue = 0xFFF0F8FF;
public static readonly ColorExtension AntiqueWhite = 0xFFFAEBD7;
public static readonly ColorExtension Aqua = 0xFF00FFFF;
public static readonly ColorExtension Aquamarine = 0xFF7FFFD4;
public static readonly ColorExtension Azure = 0xFFF0FFFF;
public static readonly ColorExtension Beige = 0xFFF5F5DC;
public static readonly ColorExtension Bisque = 0xFFFFE4C4;
public static readonly ColorExtension Black = 0xFF000000;
public static readonly ColorExtension BlanchedAlmond = 0xFFFFEBCD;
public static readonly ColorExtension Blue = 0xFF0000FF;
public static readonly ColorExtension BlueViolet = 0xFF8A2BE2;
public static readonly ColorExtension Brown = 0xFFA52A2A;
public static readonly ColorExtension BurlyWood = 0xFFDEB887;
public static readonly ColorExtension CadetBlue = 0xFF5F9EA0;
public static readonly ColorExtension Chartreuse = 0xFF7FFF00;
public static readonly ColorExtension Chocolate = 0xFFD2691E;
public static readonly ColorExtension Coral = 0xFFFF7F50;
public static readonly ColorExtension CornflowerBlue = 0xFF6495ED;
public static readonly ColorExtension Cornsilk = 0xFFFFF8DC;
public static readonly ColorExtension Crimson = 0xFFDC143C;
public static readonly ColorExtension Cyan = 0xFF00FFFF;
public static readonly ColorExtension DarkBlue = 0xFF00008B;
public static readonly ColorExtension DarkCyan = 0xFF008B8B;
public static readonly ColorExtension DarkGoldenrod = 0xFFB8860B;
public static readonly ColorExtension DarkGray = 0xFFA9A9A9;
public static readonly ColorExtension DarkGreen = 0xFF006400;
public static readonly ColorExtension DarkKhaki = 0xFFBDB76B;
public static readonly ColorExtension DarkMagenta = 0xFF8B008B;
public static readonly ColorExtension DarkOliveGreen = 0xFF556B2F;
public static readonly ColorExtension DarkOrange = 0xFFFF8C00;
public static readonly ColorExtension DarkOrchid = 0xFF9932CC;
public static readonly ColorExtension DarkRed = 0xFF8B0000;
public static readonly ColorExtension DarkSalmon = 0xFFE9967A;
public static readonly ColorExtension DarkSeaGreen = 0xFF8FBC8F;
public static readonly ColorExtension DarkSlateBlue = 0xFF483D8B;
public static readonly ColorExtension DarkSlateGray = 0xFF2F4F4F;
public static readonly ColorExtension DarkTurquoise = 0xFF00CED1;
public static readonly ColorExtension DarkViolet = 0xFF9400D3;
public static readonly ColorExtension DeepPink = 0xFFFF1493;
public static readonly ColorExtension DeepSkyBlue = 0xFF00BFFF;
public static readonly ColorExtension DimGray = 0xFF696969;
public static readonly ColorExtension DodgerBlue = 0xFF1E90FF;
public static readonly ColorExtension Firebrick = 0xFFB22222;
public static readonly ColorExtension FloralWhite = 0xFFFFFAF0;
public static readonly ColorExtension ForestGreen = 0xFF228B22;
public static readonly ColorExtension Fuchsia = 0xFFFF00FF;
public static readonly ColorExtension Gainsboro = 0xFFDCDCDC;
public static readonly ColorExtension GhostWhite = 0xFFF8F8FF;
public static readonly ColorExtension Gold = 0xFFFFD700;
public static readonly ColorExtension Goldenrod = 0xFFDAA520;
public static readonly ColorExtension Gray = 0xFF808080;
public static readonly ColorExtension Green = 0xFF008000;
public static readonly ColorExtension GreenYellow = 0xFFADFF2F;
public static readonly ColorExtension Honeydew = 0xFFF0FFF0;
public static readonly ColorExtension HotPink = 0xFFFF69B4;
public static readonly ColorExtension IndianRed = 0xFFCD5C5C;
public static readonly ColorExtension Indigo = 0xFF4B0082;
public static readonly ColorExtension Ivory = 0xFFFFFFF0;
public static readonly ColorExtension Khaki = 0xFFF0E68C;
public static readonly ColorExtension Lavender = 0xFFE6E6FA;
public static readonly ColorExtension LavenderBlush = 0xFFFFF0F5;
public static readonly ColorExtension LawnGreen = 0xFF7CFC00;
public static readonly ColorExtension LemonChiffon = 0xFFFFFACD;
public static readonly ColorExtension LightBlue = 0xFFADD8E6;
public static readonly ColorExtension LightCoral = 0xFFF08080;
public static readonly ColorExtension LightCyan = 0xFFE0FFFF;
public static readonly ColorExtension LightGoldenrodYellow = 0xFFFAFAD2;
public static readonly ColorExtension LightGray = 0xFFD3D3D3;
public static readonly ColorExtension LightGreen = 0xFF90EE90;
public static readonly ColorExtension LightPink = 0xFFFFB6C1;
public static readonly ColorExtension LightSalmon = 0xFFFFA07A;
public static readonly ColorExtension LightSeaGreen = 0xFF20B2AA;
public static readonly ColorExtension LightSkyBlue = 0xFF87CEFA;
public static readonly ColorExtension LightSlateGray = 0xFF778899;
public static readonly ColorExtension LightSteelBlue = 0xFFB0C4DE;
public static readonly ColorExtension LightYellow = 0xFFFFFFE0;
public static readonly ColorExtension Lime = 0xFF00FF00;
public static readonly ColorExtension LimeGreen = 0xFF32CD32;
public static readonly ColorExtension Linen = 0xFFFAF0E6;
public static readonly ColorExtension Magenta = 0xFFFF00FF;
public static readonly ColorExtension Maroon = 0xFF800000;
public static readonly ColorExtension MediumAquamarine = 0xFF66CDAA;
public static readonly ColorExtension MediumBlue = 0xFF0000CD;
public static readonly ColorExtension MediumOrchid = 0xFFBA55D3;
public static readonly ColorExtension MediumPurple = 0xFF9370DB;
public static readonly ColorExtension MediumSeaGreen = 0xFF3CB371;
public static readonly ColorExtension MediumSlateBlue = 0xFF7B68EE;
public static readonly ColorExtension MediumSpringGreen = 0xFF00FA9A;
public static readonly ColorExtension MediumTurquoise = 0xFF48D1CC;
public static readonly ColorExtension MediumVioletRed = 0xFFC71585;
public static readonly ColorExtension MidnightBlue = 0xFF191970;
public static readonly ColorExtension MintCream = 0xFFF5FFFA;
public static readonly ColorExtension MistyRose = 0xFFFFE4E1;
public static readonly ColorExtension Moccasin = 0xFFFFE4B5;
public static readonly ColorExtension NavajoWhite = 0xFFFFDEAD;
public static readonly ColorExtension Navy = 0xFF000080;
public static readonly ColorExtension OldLace = 0xFFFDF5E6;
public static readonly ColorExtension Olive = 0xFF808000;
public static readonly ColorExtension OliveDrab = 0xFF6B8E23;
public static readonly ColorExtension Orange = 0xFFFFA500;
public static readonly ColorExtension OrangeRed = 0xFFFF4500;
public static readonly ColorExtension Orchid = 0xFFDA70D6;
public static readonly ColorExtension PaleGoldenrod = 0xFFEEE8AA;
public static readonly ColorExtension PaleGreen = 0xFF98FB98;
public static readonly ColorExtension PaleTurquoise = 0xFFAFEEEE;
public static readonly ColorExtension PaleVioletRed = 0xFFDB7093;
public static readonly ColorExtension PapayaWhip = 0xFFFFEFD5;
public static readonly ColorExtension PeachPuff = 0xFFFFDAB9;
public static readonly ColorExtension Peru = 0xFFCD853F;
public static readonly ColorExtension Pink = 0xFFFFC0CB;
public static readonly ColorExtension Plum = 0xFFDDA0DD;
public static readonly ColorExtension PowderBlue = 0xFFB0E0E6;
public static readonly ColorExtension Purple = 0xFF800080;
public static readonly ColorExtension Red = 0xFFFF0000;
public static readonly ColorExtension RosyBrown = 0xFFBC8F8F;
public static readonly ColorExtension RoyalBlue = 0xFF4169E1;
public static readonly ColorExtension SaddleBrown = 0xFF8B4513;
public static readonly ColorExtension Salmon = 0xFFFA8072;
public static readonly ColorExtension SandyBrown = 0xFFF4A460;
public static readonly ColorExtension SeaGreen = 0xFF2E8B57;
public static readonly ColorExtension SeaShell = 0xFFFFF5EE;
public static readonly ColorExtension Sienna = 0xFFA0522D;
public static readonly ColorExtension Silver = 0xFFC0C0C0;
public static readonly ColorExtension SkyBlue = 0xFF87CEEB;
public static readonly ColorExtension SlateBlue = 0xFF6A5ACD;
public static readonly ColorExtension SlateGray = 0xFF708090;
public static readonly ColorExtension Snow = 0xFFFFFAFA;
public static readonly ColorExtension SpringGreen = 0xFF00FF7F;
public static readonly ColorExtension SteelBlue = 0xFF4682B4;
public static readonly ColorExtension Tan = 0xFFD2B48C;
public static readonly ColorExtension Teal = 0xFF008080;
public static readonly ColorExtension Thistle = 0xFFD8BFD8;
public static readonly ColorExtension Tomato = 0xFFFF6347;
public static readonly ColorExtension Transparent = 0x00FFFFFF;
public static readonly ColorExtension Turquoise = 0xFF40E0D0;
public static readonly ColorExtension Violet = 0xFFEE82EE;
public static readonly ColorExtension Wheat = 0xFFF5DEB3;
public static readonly ColorExtension White = 0xFFFFFFFF;
public static readonly ColorExtension WhiteSmoke = 0xFFF5F5F5;
public static readonly ColorExtension Yellow = 0xFFFFFF00;
public static readonly ColorExtension YellowGreen = 0xFF9ACD32;

Of course you may remove those which you don’t need. The whole work is done in the following method:

public static implicit operator Color( ColorExtension color )
{
    uint colorValue = color;
 
    return Color.FromArgb(
            ( byte )( colorValue >> 24 ),
            ( byte )( colorValue >> 16 ),
            ( byte )( colorValue >> 8 ),
            ( byte )( colorValue ) );
}

In order to complete your class you need to add the following methods:

public static implicit operator Brush( ColorExtension color )
{
    return new SolidColorBrush( color );
}
 
public static implicit operator uint( ColorExtension color )
{
    return color.value;
}
public static implicit operator ColorExtension( uint color )
{
    return new ColorExtension( color );
}

Now you can freely use all the colors you want in the code:

this.RootBorder.Background = new SolidColorBrush( ColorExtension.Tomato );
Or maybe you want to write:
this.RootBorder.Background = ColorExtension.SpringGreen;
You can download the source code and examine it.

3. References


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Comments

  • -_-

    RE: Accessing the full range of colors in procedural code


    posted by Scott Marlowe on Aug 24, 2009 17:01
    I took a very similar approach in my solution to this problem.
  • -_-

    RE: Accessing the full range of colors in procedural code


    posted by Scott Marlowe on Aug 24, 2009 17:02
    Just an fyi... I got this error message via a dialog when I posted the above comment:

    Web.config registration missing!
     The Telerik dialogs require a HttpHandler registration in the web.config file. Please, use the control's Smart Tag to add the handler automatically, or see the help for more information: Controls > Editor > Dialogs

  • ppopadiyn

    RE: Accessing the full range of colors in procedural code


    posted by ppopadiyn on Aug 24, 2009 17:26
    Hi Scott

    I read your article it is the same approach. I found the solution accidentally few weeks ago in the forum of Silverlight.net, but I lost the link. I will add a reference to your article, you defenitely add some more details. Thanks.

  • -_-

    RE: Accessing the full range of colors in procedural code


    posted by Doug on Sep 10, 2009 16:48
    Hi,

    when I add your class in my silverlight-application, I can't compile it.

    Here I get an Error:

     

    public static implicit operator Brush( ColorExtension color ) 
        return new SolidColorBrush( color );  // Here I get an error 

     

    The Argument "ColorExtension" can not convert to "System.Windows.Media.Color".

    Thanks

  • -_-

    RE: Accessing the full range of colors in procedural code


    posted by Doug on Sep 10, 2009 17:49
    Hi,

    when I add your class in my silverlight-application, I can't compile it.

    Here I get an Error:

     

    public static implicit operator Brush( ColorExtension color ) 
        return new SolidColorBrush( color );  // Here I get an error 

     

    The Argument "ColorExtension" can not convert to "System.Windows.Media.Color".

    Thanks

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