LinkUtilities.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / WinForms / Managed / System / WinForms / LinkUtilities.cs / 1 / LinkUtilities.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Windows.Forms { 
using System; 
using System.Drawing;
using System.Windows.Forms; 
using Microsoft.Win32;
using System.Globalization;
using System.Security.Permissions;
 
    internal class LinkUtilities {
 
        // IE fonts and colors 
        static Color ielinkColor = Color.Empty;
        static Color ieactiveLinkColor = Color.Empty; 
        static Color ievisitedLinkColor = Color.Empty;

        const string IESettingsRegPath = "Software\\Microsoft\\Internet Explorer\\Settings";
        public const string IEMainRegPath = "Software\\Microsoft\\Internet Explorer\\Main"; 
        const string IEAnchorColor = "Anchor Color";
        const string IEAnchorColorVisited = "Anchor Color Visited"; 
        const string IEAnchorColorHover = "Anchor Color Hover"; 

        ///  
        /// 
        ///     Retrieves a named IE color from the registry. There are constants at the top
        ///     of this file of the valid names to retrieve.
        ///  
        private static Color GetIEColor(string name) {
            // SECREVIEW : We are just reading the IE color settings from the registry... 
            // 
            // SECUNDONE : This assert doesn't work... assert everything for now...
            // 
            //new RegistryPermission(RegistryPermissionAccess.Read, "HKCU\\" + IESettingsRegPath).Assert();
            new RegistryPermission(PermissionState.Unrestricted).Assert();
            try {
                RegistryKey key = Registry.CurrentUser.OpenSubKey(IESettingsRegPath); 

                if (key != null) { 
 
                    // Since this comes from the registry, be very careful about its contents.
                    // 
                    string s = (string)key.GetValue(name);
                    if (s != null) {
                        string[] rgbs = s.Split(new char[] {','});
                        int[] rgb = new int[3]; 

                        int nMax = Math.Min(rgb.Length, rgbs.Length); 
 
                        //NOTE: if we can't parse rgbs[i], rgb[i] will be set to 0.
                        for (int i = 0; i < nMax; i++) 
                        {
                            int.TryParse(rgbs[i], out rgb[i]);
                        }
 
                        return Color.FromArgb(rgb[0], rgb[1], rgb[2]);
                    } 
                } 

                if (string.Equals(name, IEAnchorColor, StringComparison.OrdinalIgnoreCase)) { 
                    return Color.Blue;
                }
                else if (string.Equals(name, IEAnchorColorVisited, StringComparison.OrdinalIgnoreCase)) {
                    return Color.Purple; 
                }
                else if (string.Equals(name, IEAnchorColorHover, StringComparison.OrdinalIgnoreCase)) { 
                    return Color.Red; 
                }
                else { 
                    return Color.Red;
                }
            }
            finally { 
                System.Security.CodeAccessPermission.RevertAssert();
            } 
 
        }
 
        public static Color IELinkColor {
            get {
                if (ielinkColor.IsEmpty) {
                    ielinkColor = GetIEColor(IEAnchorColor); 
                }
                return ielinkColor; 
            } 
        }
 
        public static Color IEActiveLinkColor {
            get {
                if (ieactiveLinkColor.IsEmpty) {
                    ieactiveLinkColor = GetIEColor(IEAnchorColorHover); 
                }
                return ieactiveLinkColor; 
            } 
        }
        public static Color IEVisitedLinkColor { 
            get {
                if (ievisitedLinkColor.IsEmpty) {
                    ievisitedLinkColor = GetIEColor(IEAnchorColorVisited);
                } 
                return ievisitedLinkColor;
            } 
        } 

        ///  
        /// 
        ///     Retrieves the IE settings for link behavior from the registry.
        /// 
        public static LinkBehavior GetIELinkBehavior() { 
            // SECREVIEW : We are just reading the IE color settings from the registry...
            // 
            // SECUNDONE : This assert doesn't work... assert everything for now... 
            //
            //new RegistryPermission(RegistryPermissionAccess.Read, "HKCU\\" + IEMainRegPath).Assert(); 
            new RegistryPermission(PermissionState.Unrestricted).Assert();
            try {
                RegistryKey key = Registry.CurrentUser.OpenSubKey(IEMainRegPath);
                if (key != null) { 
                    string s = (string)key.GetValue("Anchor Underline");
 
                    if (s != null && string.Compare(s, "no", true, CultureInfo.InvariantCulture) == 0) { 
                        return LinkBehavior.NeverUnderline;
                    } 
                    if (s != null && string.Compare(s, "hover", true, CultureInfo.InvariantCulture) == 0) {
                        return LinkBehavior.HoverUnderline;
                    }
                    else { 
                        return LinkBehavior.AlwaysUnderline;
                    } 
                } 
            }
            finally { 
                System.Security.CodeAccessPermission.RevertAssert();
            }

            return LinkBehavior.AlwaysUnderline; 
        }
 
        public static void EnsureLinkFonts(Font baseFont, LinkBehavior link, ref Font linkFont, ref Font hoverLinkFont) { 
            if (linkFont != null && hoverLinkFont != null) {
                return; 
            }

            bool underlineLink = true;
            bool underlineHover = true; 

            if (link == LinkBehavior.SystemDefault) { 
                link = GetIELinkBehavior(); 
            }
 
            switch (link) {
                case LinkBehavior.AlwaysUnderline:
                    underlineLink = true;
                    underlineHover = true; 
                    break;
                case LinkBehavior.HoverUnderline: 
                    underlineLink = false; 
                    underlineHover = true;
                    break; 
                case LinkBehavior.NeverUnderline:
                    underlineLink = false;
                    underlineHover = false;
                    break; 
            }
 
            Font f = baseFont; 

            // We optimize for the "same" value (never & always) to avoid creating an 
            // extra font object.
            //
            if (underlineHover == underlineLink) {
                FontStyle style = f.Style; 
                if (underlineHover) {
                    style |= FontStyle.Underline; 
                } 
                else {
                    style &= ~FontStyle.Underline; 
                }
                hoverLinkFont = new Font(f, style);
                linkFont = hoverLinkFont;
            } 
            else {
                FontStyle hoverStyle = f.Style; 
                if (underlineHover) { 
                    hoverStyle |= FontStyle.Underline;
                } 
                else {
                    hoverStyle &= ~FontStyle.Underline;
                }
 
                hoverLinkFont = new Font(f, hoverStyle);
 
                FontStyle linkStyle = f.Style; 
                if (underlineLink) {
                    linkStyle |= FontStyle.Underline; 
                }
                else {
                    linkStyle &= ~FontStyle.Underline;
                } 

                linkFont = new Font(f, linkStyle); 
            } 
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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LinkUtilities.cs source code in C# .NET

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