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//------------------------------------------------------------------------------
// <copyright file="LinkUtilities.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
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";
/// <include file='doc\LinkUtilities.uex' path='docs/doc[@for="LinkUtilities.GetIEColor"]/*' />
/// <devdoc>
/// Retrieves a named IE color from the registry. There are constants at the top
/// of this file of the valid names to retrieve.
/// </devdoc>
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);
key.Close();
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;
}
}
/// Produces a color for visited links using SystemColors
public static Color GetVisitedLinkColor()
{
int r = (SystemColors.Window.R + SystemColors.WindowText.R + 1) / 2;
int g = SystemColors.WindowText.G;
int b = (SystemColors.Window.B + SystemColors.WindowText.B + 1) / 2;
return Color.FromArgb(r, g, b);
}
/// <include file='doc\LinkUtilities.uex' path='docs/doc[@for="LinkUtilities.GetIELinkBehavior"]/*' />
/// <devdoc>
/// Retrieves the IE settings for link behavior from the registry.
/// </devdoc>
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 = null;
try {
key = Registry.CurrentUser.OpenSubKey(IEMainRegPath);
}
catch (System.Security.SecurityException) {
// User does not have right to access Registry path HKCU\\Software\\Microsoft\\Internet Explorer\\Main.
// Catch SecurityException silently and let the return value fallback to AlwaysUnderline.
}
if (key != null) {
string s = (string)key.GetValue("Anchor Underline");
key.Close();
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);
}
}
}
}
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