//------------------------------------------------------------------------------
// <copyright file="OSFeature.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>                                                                
//------------------------------------------------------------------------------
 
namespace System.Windows.Forms {
    using System.Configuration.Assemblies;
    using System.Diagnostics;
    using System;
    using System.Security;
    using System.Security.Permissions;
 
    /// <include file='doc\OSFeature.uex' path='docs/doc[@for="OSFeature"]/*' />
    /// <devdoc>
    ///    <para>Provides operating-system specific feature queries.</para>
    /// </devdoc>
    public class OSFeature : FeatureSupport {
 
        /// <include file='doc\OSFeature.uex' path='docs/doc[@for="OSFeature.LayeredWindows"]/*' />
        /// <devdoc>
        ///    <para>Represents the layered, top-level windows feature. This
        ///    <see langword='static'/> field is read-only.</para>
        /// </devdoc>
        public static readonly object LayeredWindows = new object();
        
        /// <include file='doc\OSFeature.uex' path='docs/doc[@for="OSFeature.Themes"]/*' />
        /// <devdoc>
        ///    <para>Determines if the OS supports themes</para>
        /// </devdoc>
        public static readonly object Themes = new object();
 
        private static OSFeature feature = null;
 
        private static bool themeSupportTested = false;
        private static bool themeSupport = false;
 
        /// <include file='doc\OSFeature.uex' path='docs/doc[@for="OSFeature.OSFeature"]/*' />
        /// <internalonly/>
        /// <devdoc>
        ///    <para>
        ///       Initializes a new instance of the <see cref='System.Windows.Forms.OSFeature'/> class.
        ///       
        ///    </para>
        /// </devdoc>
        protected OSFeature() {
        }
 
        /// <include file='doc\OSFeature.uex' path='docs/doc[@for="OSFeature.Feature"]/*' />
        /// <devdoc>
        /// <para>Represents the <see langword='static'/> instance of <see cref='System.Windows.Forms.OSFeature'/> to use for feature queries. This property is read-only.</para>
        /// </devdoc>
        public static OSFeature Feature {
            get {
                if (feature == null)
                    feature = new OSFeature();
                    
                return feature;
            }
        }
        
        /// <include file='doc\OSFeature.uex' path='docs/doc[@for="OSFeature.GetVersionPresent"]/*' />
        /// <devdoc>
        ///    <para>Retrieves the version of the specified feature currently available on the system.</para>
        /// </devdoc>
        public override Version GetVersionPresent(object feature) {
            Version featureVersion = null;
            if (feature == LayeredWindows) {
                if (Environment.OSVersion.Platform == System.PlatformID.Win32NT
                   && Environment.OSVersion.Version.CompareTo(new Version(5, 0, 0, 0)) >= 0) {
 
                    featureVersion = new Version(0, 0, 0, 0);
                }
            }
            else if (feature == Themes) {
                if (!themeSupportTested) {
                    try {
                        SafeNativeMethods.IsAppThemed();
                        themeSupport = true;
                    }
                    catch {
                        themeSupport = false;
                    }
                    themeSupportTested = true;
                }
 
                if (themeSupport) {
                    featureVersion = new Version(0, 0, 0, 0);
                }
            }
            return featureVersion;
        }
 
        internal bool OnXp {
            get {
                bool onXp = false;
                if (Environment.OSVersion.Platform == System.PlatformID.Win32NT) {
                    onXp =  Environment.OSVersion.Version.CompareTo(new Version(5, 1, 0, 0)) >= 0;
                }
                return onXp;
            }
        }
 
        internal bool OnWin2k {
            get {
                bool onWin2k = false;
                if (Environment.OSVersion.Platform == System.PlatformID.Win32NT) {
                    onWin2k =  Environment.OSVersion.Version.CompareTo(new Version(5, 0, 0, 0)) >= 0;
                }
                return onWin2k;
            }
        }
 
        /// <include file='doc\OSFeature.uex' path='docs/doc[@for="OSFeature.IsPresent"]/*' />
        /// <devdoc>
        ///    <para>Retrieves whether SystemParameterType is supported on the Current OS version.</para>
        /// </devdoc>
        public static bool IsPresent(SystemParameter enumVal) {
            switch (enumVal) {
                case SystemParameter.DropShadow:
                    return Feature.OnXp;
                    
 
                case SystemParameter.FlatMenu:
                    return Feature.OnXp;
                    
 
                case SystemParameter.FontSmoothingContrastMetric:
                    return Feature.OnXp;
                    
                        
                case SystemParameter.FontSmoothingTypeMetric:
                    return Feature.OnXp;
                    
 
                case SystemParameter.MenuFadeEnabled:
                    return Feature.OnWin2k;
                    
               
                case SystemParameter.SelectionFade:
                    return Feature.OnWin2k;
                    
 
                case SystemParameter.ToolTipAnimationMetric:
                    return Feature.OnWin2k;
                    
 
                case SystemParameter.UIEffects:
                    return Feature.OnWin2k;
                    
 
                case SystemParameter.CaretWidthMetric:
                    return Feature.OnWin2k;
                    
 
                case SystemParameter.VerticalFocusThicknessMetric:
                    return Feature.OnXp;
                    
 
                case SystemParameter.HorizontalFocusThicknessMetric:
                    return Feature.OnXp;
            }
            return false;
        }
 
    }
}