FontFamilyConverter.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Core / System / Windows / Media / FontFamilyConverter.cs / 1 / FontFamilyConverter.cs
                        
                        
                            //+------------------------------------------------------------------------ 
//
//  Microsoft Windows Client Platform
//  Copyright (C) Microsoft Corporation, 2002
// 
//  File:      FontFamilyConverter.cs
// 
//  Contents:  FontFamilyConverter implementation 
//
//  Spec:      [....]/sites/Avalon/Specs/Fonts.htm 
//
//  Created:   2-1-2005 [....] ([....])
//
//----------------------------------------------------------------------- 

using System; 
using System.ComponentModel; 
using System.ComponentModel.Design.Serialization;
using System.Diagnostics; 
using System.Globalization;
using System.Windows.Navigation;
using System.Windows.Markup;
 
using SR=MS.Internal.PresentationCore.SR;
using SRID=MS.Internal.PresentationCore.SRID; 
 
// Allow suppression of presharp warnings
#pragma warning disable 1634, 1691 

namespace System.Windows.Media
{
    ///  
    /// FontFamilyConverter - converter class for converting between the FontFamily
    /// and String types. 
    ///  
    public class FontFamilyConverter : TypeConverter
    { 
        /// 
        /// CanConvertFrom - Returns whether or not the given type can be converted to a
        /// FontFamily.
        ///  
        public override bool CanConvertFrom(ITypeDescriptorContext td, Type t)
        { 
            return t == typeof(string); 
        }
 
        /// 
        /// CanConvertTo - Returns whether or not this class can convert to the specified type.
        /// Conversion is possible only if the source and destination types are FontFamily and
        /// string, respectively, and the font family is not anonymous (i.e., the Source propery 
        /// is not null).
        ///  
        /// ITypeDescriptorContext 
        /// Type to convert to
        /// true if conversion is possible 
        public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
        {
            if (destinationType == typeof(string))
            { 
                if (context != null)
                { 
                    // When serializing to XAML we want to write the FontFamily as an attribute if and 
                    // only if it's a named font family.
                    FontFamily fontFamily = context.Instance as FontFamily; 

                    // Suppress PRESharp warning that fontFamily can be null; apparently PRESharp
                    // doesn't understand short circuit evaluation of operator &&.
#pragma warning suppress 56506 
                    return fontFamily != null && fontFamily.Source != null && fontFamily.Source.Length != 0;
                } 
                else 
                {
                    // Some clients call typeConverter.CanConvertTo(typeof(string)), in which case we 
                    // don't have the FontFamily instance to convert. Most font families are named, and
                    // we can always give some kind of name, so return true.
                    return true;
                } 
            }
            else if (destinationType == typeof(FontFamily)) 
            { 
                return true;
            } 
            return base.CanConvertTo(context, destinationType);
        }

        ///  
        /// ConvertFrom - Converts the specified object to a FontFamily.
        ///  
        public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo cultureInfo, object o) 
        {
            if ((o != null) && (o.GetType() == typeof(string))) 
            {
                string s = o as string;

                if (s == null || s.Length == 0) 
                {
                    throw GetConvertFromException(s); 
                } 

                // Logic below is similar to TypeConverterHelper.GetUriFromUriContext, 
                // except that we cannot treat font family string as a Uri,
                // and that we handle cases when context is null.

                Uri baseUri = null; 

                if (context != null) 
                { 
                    IUriContext iuc = (IUriContext)context.GetService(typeof(IUriContext));
                    if (iuc != null) 
                    {
                        if (iuc.BaseUri != null)
                        {
                            baseUri = iuc.BaseUri; 

                            if (!baseUri.IsAbsoluteUri) 
                            { 
                                baseUri = new Uri(BaseUriHelper.BaseUri, baseUri);
                            } 
                        }
                        else
                        {
                            // If we reach here, the base uri we got from IUriContext is "". 
                            // Here we resolve it to application's base
                            baseUri = BaseUriHelper.BaseUri; 
                        } 
                    }
                } 

                return new FontFamily(baseUri, s);
            }
            return base.ConvertFrom(context, cultureInfo, o); ; 
        }
 
        ///  
        /// ConvertTo - Converts the specified object to an instance of the specified type.
        ///  
        public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
        {
            if (null == value)
            { 
                throw new ArgumentNullException("value");
            } 
 
            FontFamily fontFamily = value as FontFamily;
            if (fontFamily == null) 
            {
                throw new ArgumentException(SR.Get(SRID.General_Expected_Type, "FontFamily"), "value");
            }
 
            if (null == destinationType)
            { 
                throw new ArgumentNullException("destinationType"); 
            }
 
            if (destinationType == typeof(string))
            {
                if (fontFamily.Source != null)
                { 
                    // Usual case: it's a named font family.
                    return fontFamily.Source; 
                } 
                else
                { 
                    // If client calls typeConverter.CanConvertTo(typeof(string)) then we'll return
                    // true always, even though we don't have access to the FontFamily instance; so
                    // we need to be able to return some kind of family name even if Source==null.
                    string name = null; 

                    CultureInfo parentCulture = null; 
                    if (culture != null) 
                    {
                        if (culture.Equals(CultureInfo.InvariantCulture)) 
                        {
                            culture = null;
                        }
                        else 
                        {
                            parentCulture = culture.Parent; 
                            if (parentCulture != null && 
                                (parentCulture.Equals(CultureInfo.InvariantCulture) || parentCulture == culture))
                            { 
                                parentCulture = null;
                            }
                        }
                    } 

                    // Try looking up the name in the FamilyNames dictionary. 
                    LanguageSpecificStringDictionary names = fontFamily.FamilyNames; 

                    if (culture != null && names.TryGetValue(XmlLanguage.GetLanguage(culture.IetfLanguageTag), out name)) 
                    {
                        // LanguageSpecificStringDictionary does not allow null string to be added.
                        Debug.Assert(name != null);
                    } 
                    else if (parentCulture != null && names.TryGetValue(XmlLanguage.GetLanguage(parentCulture.IetfLanguageTag), out name))
                    { 
                        // LanguageSpecificStringDictionary does not allow null string to be added. 
                        Debug.Assert(name != null);
                    } 
                    else if (names.TryGetValue(XmlLanguage.Empty, out name))
                    {
                        // LanguageSpecificStringDictionary does not allow null string to be added.
                        Debug.Assert(name != null); 
                    }
                    else 
                    { 
                        // Try the first target font compatible with the culture.
                        foreach (FontFamilyMap familyMap in fontFamily.FamilyMaps) 
                        {
                            if (FontFamilyMap.MatchCulture(familyMap.Language, culture))
                            {
                                name = familyMap.Target; 
                                break;
                            } 
                        } 

                        // Use global ui as a last resort. 
                        if (name == null)
                            name = FontFamily.GlobalUI;
                    }
 
                    return name;
                } 
            } 

            return base.ConvertTo(context, culture, value, destinationType); 
        }
    }
}

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

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