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AngleSharp

, 3 Jul 2013 BSD
Bringing the DOM to C# with a HTML5/CSS3 parser written in C#.
Demo.zip
AngleSharp
Css
Tokens
DOM
Collections
Css
Properties
Rules
Selector
Values
Enums
Exception
Html
Basic
Formatting
Forms
Frames
Head
Lists
Media
Objects
Semantic
Tables
Interfaces
Mathml
Objects
Svg
Various
Xml
Foundation
Attributes
Helpers
Mutations
Html
Tokens
Properties
Stream
Xml
Tokens
packages
ModernUI.WPF.1.0.4
lib
net40
FirstFloor.ModernUI.dll
Microsoft.Windows.Shell.dll
net45
FirstFloor.ModernUI.dll
ModernUI.WPF.1.0.4.nupkg
ModernUI.WPF.1.0.4.nuspec
OxyPlot.Core.2013.1.49.1
lib
portable-net4+sl4+wp71+win8
OxyPlot.dll
OxyPlot.Core.2013.1.49.1.nupkg
OxyPlot.Core.2013.1.49.1.nuspec
OxyPlot.Wpf.2013.1.49.1
lib
NET40
OxyPlot.Wpf.dll
OxyPlot.Xps.dll
NET45
OxyPlot.Wpf.dll
OxyPlot.Xps.dll
OxyPlot.Wpf.2013.1.49.1.nupkg
OxyPlot.Wpf.2013.1.49.1.nuspec
Samples
Logo.ico
Pages
Properties
Settings.settings
ViewModels
Source.zip
Documents
using System;
using System.Runtime.InteropServices;

namespace AngleSharp
{
    /// <summary>
    /// Represents a color value.
    /// </summary>
    [StructLayout(LayoutKind.Explicit, Pack = 1, CharSet = CharSet.Unicode)]
    struct HtmlColor : IEquatable<HtmlColor>
    {
        //TODO
        //http://en.wikipedia.org/wiki/Alpha_compositing

        #region Members

        [FieldOffset(0)]
        Byte alpha;
        [FieldOffset(1)]
        Byte red;
        [FieldOffset(2)]
        Byte green;
        [FieldOffset(3)]
        Byte blue;
        [FieldOffset(0)]
        Int32 hashcode;

        #endregion

        #region ctor

        /// <summary>
        /// Creates an Html color type without any transparency (alpha = 100%).
        /// </summary>
        /// <param name="r">The red value.</param>
        /// <param name="g">The green value.</param>
        /// <param name="b">The blue value.</param>
        public HtmlColor(Byte r, Byte g, Byte b)
        {
            hashcode = 0;
            alpha = 255;
            red = r;
            blue = b;
            green = g;
        }

        /// <summary>
        /// Creates an Html color type.
        /// </summary>
        /// <param name="a">The alpha value.</param>
        /// <param name="r">The red value.</param>
        /// <param name="g">The green value.</param>
        /// <param name="b">The blue value.</param>
        public HtmlColor(Byte a, Byte r, Byte g, Byte b)
        {
            hashcode = 0;
            alpha = a;
            red = r;
            blue = b;
            green = g;
        }

        /// <summary>
        /// Creates an Html color type.
        /// </summary>
        /// <param name="a">The alpha value between 0 and 1.</param>
        /// <param name="r">The red value.</param>
        /// <param name="g">The green value.</param>
        /// <param name="b">The blue value.</param>
        public HtmlColor(Double a, Byte r, Byte g, Byte b)
        {
            hashcode = 0;
            alpha = (Byte)Math.Max(Math.Min(Math.Ceiling(255 * a), 255), 0);
            red = r;
            blue = b;
            green = g;
        }

        #endregion

        #region Static constructors

        /// <summary>
        /// Returns the color from the given primitives.
        /// </summary>
        /// <param name="r">The value for red.</param>
        /// <param name="g">The value for green.</param>
        /// <param name="b">The value for blue.</param>
        /// <param name="a">The value for alpha.</param>
        /// <returns>The HTML color value.</returns>
        public static HtmlColor FromRgba(Byte r, Byte g, Byte b, Single a)
        {
            return new HtmlColor(a, r, g, b);
        }

        /// <summary>
        /// Returns the color from the given primitives.
        /// </summary>
        /// <param name="r">The value for red.</param>
        /// <param name="g">The value for green.</param>
        /// <param name="b">The value for blue.</param>
        /// <param name="a">The value for alpha.</param>
        /// <returns>The HTML color value.</returns>
        public static HtmlColor FromRgba(Byte r, Byte g, Byte b, Double a)
        {
            return new HtmlColor(a, r, g, b);
        }

        /// <summary>
        /// Returns the color from the given primitives without any alpha (non-transparent).
        /// </summary>
        /// <param name="r">The value for red.</param>
        /// <param name="g">The value for green.</param>
        /// <param name="b">The value for blue.</param>
        /// <returns>The HTML color value.</returns>
        public static HtmlColor FromRgb(Byte r, Byte g, Byte b)
        {
            return new HtmlColor(r, g, b);
        }

        /// <summary>
        /// Returns the color from the given hex string.
        /// </summary>
        /// <param name="color">The hex string like fff or abc123 or AA126B etc.</param>
        /// <returns>The HTML color value.</returns>
        public static HtmlColor FromHex(String color)
        {
            if (color.Length == 3)
            {
                int r = color[0].FromHex();
                r += r * 16;
                int g = color[1].FromHex();
                g += g * 16;
                int b = color[2].FromHex();
                b += b * 16;

                return new HtmlColor((byte)r, (byte)g, (byte)b);
            }
            else if (color.Length == 6)
            {
                int r = 16 * color[0].FromHex();
                int g = 16 * color[2].FromHex();
                int b = 16 * color[4].FromHex();
                r += color[1].FromHex();
                g += color[3].FromHex();
                b += color[5].FromHex();

                return new HtmlColor((byte)r, (byte)g, (byte)b);
            }

            return new HtmlColor();
        }

        /// <summary>
        /// Returns the color from the given hex string if it can be converted, otherwise
        /// the color is not set.
        /// </summary>
        /// <param name="color">The hexadecimal reresentation of the color.</param>
        /// <param name="htmlColor">The color value to be created.</param>
        /// <returns>The status if the string can be converted.</returns>
        public static Boolean TryFromHex(String color, out HtmlColor htmlColor)
        {
            htmlColor = new HtmlColor();
            htmlColor.alpha = 255;

            if (color.Length == 3)
            {
                if (!Specification.IsHex(color[0]) || !Specification.IsHex(color[1]) || !Specification.IsHex(color[2]))
                    return false;

                var r = color[0].FromHex();
                r += r * 16;
                var g = color[1].FromHex();
                g += g * 16;
                var b = color[2].FromHex();
                b += b * 16;

                htmlColor.red = (Byte)r;
                htmlColor.green = (Byte)g;
                htmlColor.blue = (Byte)b;
                return true;
            }
            else if (color.Length == 6)
            {
                if (!Specification.IsHex(color[0]) || !Specification.IsHex(color[1]) || !Specification.IsHex(color[2]) ||
                    !Specification.IsHex(color[3]) || !Specification.IsHex(color[4]) || !Specification.IsHex(color[5]))
                    return false;

                var r = 16 * color[0].FromHex();
                var g = 16 * color[2].FromHex();
                var b = 16 * color[4].FromHex();
                r += color[1].FromHex();
                g += color[3].FromHex();
                b += color[5].FromHex();

                htmlColor.red = (Byte)r;
                htmlColor.green = (Byte)g;
                htmlColor.blue = (Byte)b;
                return true;
            }

            return false;
        }

        #endregion

        #region Properties

        /// <summary>
        /// Gets the Int32 value of the color.
        /// </summary>
        public Int32 Value
        {
            get { return hashcode; }
        }

        /// <summary>
        /// Gets the alpha part of the color.
        /// </summary>
        public Byte A
        {
            get { return alpha; }
        }

        /// <summary>
        /// Gets the alpha part of the color in percent (0..1).
        /// </summary>
        public Double Alpha
        {
            get { return alpha / 255.0; }
        }

        /// <summary>
        /// Gets the red part of the color.
        /// </summary>
        public Byte R
        {
            get { return red; }
        }

        /// <summary>
        /// Gets the green part of the color.
        /// </summary>
        public Byte G
        {
            get { return green; }
        }

        /// <summary>
        /// Gets the blue part of the color.
        /// </summary>
        public Byte B
        {
            get { return blue; }
        }

        #endregion

        #region Operators

        public static Boolean operator ==(HtmlColor a, HtmlColor b)
        {
            return a.hashcode == b.hashcode;
        }

        public static Boolean operator !=(HtmlColor a, HtmlColor b)
        {
            return a.hashcode != b.hashcode;
        }

        #endregion

        #region Overrides

        /// <summary>
        /// Tests if another object is equal to this object.
        /// </summary>
        /// <param name="obj">The object to test with.</param>
        /// <returns>True if the two objects are equal, otherwise false.</returns>
        public override Boolean Equals(Object obj)
        {
            if (obj is HtmlColor)
                return this.Equals((HtmlColor)obj);

            return false;
        }

        /// <summary>
        /// Returns a hash code that defines the current color.
        /// </summary>
        /// <returns>The integer value of the hashcode.</returns>
        public override Int32 GetHashCode()
        {
            return hashcode;
        }

        /// <summary>
        /// Returns a string representing the color.
        /// </summary>
        /// <returns>The RGBA string.</returns>
        public override String ToString()
        {
            return String.Format("rgba({0}, {1}, {2}, {3})", red, green, blue, alpha / 255.0);
        }

        #endregion

        #region Implementing Interface

        public Boolean Equals(HtmlColor other)
        {
            return this.hashcode == other.hashcode;
        }

        #endregion

        #region String representation

        /// <summary>
        /// Returns a string containing the CSS code.
        /// </summary>
        /// <returns>The string with the rgb or rgba code.</returns>
        public String ToCss()
        {
            if (alpha == 255)
                return "rgb(" + red.ToString() + ", " + green.ToString() + ", " + blue.ToString() + ")";

            return "rgba(" + red.ToString() + ", " + green.ToString() + ", " + blue.ToString() + ", " + Alpha.ToString() + ")";
        }

        /// <summary>
        /// Returns a string containing the HTML (hex) code.
        /// </summary>
        /// <returns>The string with the hex code color.</returns>
        public String ToHtml()
        {
            return "#" + red.ToHex() + green.ToHex() + blue.ToHex();
        }

        #endregion
    }
}

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License

This article, along with any associated source code and files, is licensed under The BSD License

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About the Author

Florian Rappl
Chief Technology Officer
Germany Germany
Florian is from Regensburg, Germany. He started his programming career with Perl. After programming C/C++ for some years he discovered his favorite programming language C#. He did work at Siemens as a programmer until he decided to study Physics. During his studies he worked as an IT consultant for various companies.
 
Florian is also giving lectures in C#, HTML5 with CSS3 and JavaScript, and other topics. Having graduated from University with a Master's degree in theoretical physics he is currently busy doing his PhD in the field of High Performance Computing.
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