Fonts.cs source code in C# .NET

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Code:

/ Net / Net / 3.5.50727.3053 / DEVDIV / depot / DevDiv / releases / Orcas / SP / wpf / src / Core / CSharp / System / Windows / Media / Fonts.cs / 1 / Fonts.cs

                            //---------------------------------------------------------------------------- 
//
// Copyright (c) Microsoft Corporation.  All rights reserved.
//
// Description: The Fonts class provides font enumeration APIs. 
//              See spec at http://avalon/text/DesignDocsAndSpecs/Font%20Enumeration%20API.htm
// 
// 
// History:
//  03/02/2004 : mleonov - Created 
//
//---------------------------------------------------------------------------

using System; 
using System.Text;
using System.IO; 
using System.Globalization; 
using System.Collections;
using System.Collections.Generic; 
using System.Diagnostics;
using System.Windows;

using MS.Internal; 
using MS.Internal.FontCache;
using MS.Internal.FontFace; 
using MS.Internal.PresentationCore; 
using MS.Internal.Shaping;
using System.Security; 

namespace System.Windows.Media
{
    ///  
    /// The FontEmbeddingManager class provides font enumeration APIs.
    ///  
    public static class Fonts 
    {
        //----------------------------------------------------- 
        //
        //  Public Methods
        //
        //----------------------------------------------------- 

        #region Public Methods 
 
        /// 
        /// Enumerates font families from an arbitrary location. 
        /// 
        /// An absolute URI of a folder containing fonts or a font file.
        /// Collection of FontFamily objects from the specified folder or file.
        ///  
        /// The specified location must be an absolute file URI or path, and the caller must have
        /// FileIOPermission(FileIOPermissionAccess.Read) for the location. Each resulting FontFamily 
        /// object includes the specified location in its friendly name and has no base URI. 
        /// 
        public static ICollection GetFontFamilies(string location) 
        {
            if (location == null)
                throw new ArgumentNullException("location");
 
            return GetFontFamilies(null, location);
        } 
 
        /// 
        /// Enumerates font families in the same folder as the specified base URI. 
        /// 
        /// An absolute URI of a folder containing fonts or a resource in that folder.
        /// Collection of FontFamily objects from the specified folder.
        ///  
        /// The caller must have FileIOPermission(FileIOPermissionAccess.Read) for the folder
        /// specified by baseUri. Each resulting FontFamily object has the specified Uri as its 
        /// BaseUri property has a friendly name of the form "./#Family Name". 
        /// 
        public static ICollection GetFontFamilies(Uri baseUri) 
        {
            if (baseUri == null)
                throw new ArgumentNullException("baseUri");
 
            return GetFontFamilies(baseUri, null);
        } 
 

        ///  
        /// Enumerates font families in the font location specified by a base URI and/or a location string.
        /// 
        /// Base URI used to determine the font location if the location parameter is not specified
        /// or is relative, and the value of the BaseUri property of each FontFamily in the resulting collection. This 
        /// parameter can be null if the location parameter specifies an absolute location.
        /// Optional relative or absolute URI reference. The location is used (with baseUri) to 
        /// determine the font folder and is exposed as part of the Source property of each FontFamily in the resulting 
        /// collection. If location is null or empty then "./" is implied, meaning same folder as the base URI.
        /// Collection of FontFamily objects from the specified font location. 
        /// 
        /// The caller must have FileIOPermission(FileIOPermissionAccess.Read) for the specified font folder.
        /// Each resulting FontFamily object has the specified base Uri as its BaseUri property and includes the
        /// specified location as part of the friendly name specified by the Source property. 
        /// 
        public static ICollection GetFontFamilies(Uri baseUri, string location) 
        { 
            // Both Uri parameters are optional but neither can be relative.
            if (baseUri != null && !baseUri.IsAbsoluteUri) 
                throw new ArgumentException(SR.Get(SRID.UriNotAbsolute), "baseUri");

            // Determine the font location from the base URI and location string.
            Uri fontLocation; 
            if (!string.IsNullOrEmpty(location) && Uri.TryCreate(location, UriKind.Absolute, out fontLocation))
            { 
                // absolute location; make sure we support absolute font family references for this scheme 
                if (!Util.IsSupportedSchemeForAbsoluteFontFamilyUri(fontLocation))
                    throw new ArgumentException(SR.Get(SRID.InvalidAbsoluteUriInFontFamilyName), "location"); 

                // make sure the absolute location is a valid URI reference rather than a Win32 path as
                // we don't support the latter in a font family reference
                location = fontLocation.GetComponents(UriComponents.AbsoluteUri, UriFormat.SafeUnescaped); 
            }
            else 
            { 
                // relative location; we need a base URI
                if (baseUri == null) 
                    throw new ArgumentNullException("baseUri", SR.Get(SRID.NullBaseUriParam, "baseUri", "location"));

                // the location part must include a path component, otherwise we'll look in windows fonts and ignore the base URI
                if (string.IsNullOrEmpty(location)) 
                    location = "./";
                else if (Util.IsReferenceToWindowsFonts(location)) 
                    location = "./" + location; 

                fontLocation = new Uri(baseUri, location); 
            }

            // Create the font families.
            return CreateFamilyCollection( 
                fontLocation,   // fontLocation
                baseUri,        // fontFamilyBaseUri 
                location        // fontFamilyLocationReference 
                );
        } 


        /// 
        /// Enumerates typefaces from an arbitrary location. 
        /// 
        /// An absolute URI of a folder containing fonts or a font file. 
        /// Collection of Typeface objects from the specified folder or file. 
        /// 
        /// The specified location must be an absolute file URI or path, and the caller must have 
        /// FileIOPermission(FileIOPermissionAccess.Read) for the location. The FontFamily of each
        /// resulting Typeface object includes the specified location in its friendly name and has
        /// no base URI.
        ///  
        public static ICollection GetTypefaces(string location)
        { 
            if (location == null) 
                throw new ArgumentNullException("location");
 
            return new TypefaceCollection(GetFontFamilies(null, location));
        }

        ///  
        /// Enumerates typefaces in the same folder as the specified base URI.
        ///  
        /// An absolute URI of a folder containing fonts or a resource in that folder. 
        /// Collection of Typeface objects from the specified folder.
        ///  
        /// The caller must have FileIOPermission(FileIOPermissionAccess.Read) for the folder
        /// specified by baseUri. The FontFamily of each resulting Typeface object has the specified
        /// Uri as its BaseUri property has a friendly name of the form "./#Family Name".
        ///  
        public static ICollection GetTypefaces(Uri baseUri)
        { 
            if (baseUri == null) 
                throw new ArgumentNullException("baseUri");
 
            return new TypefaceCollection(GetFontFamilies(baseUri, null));
        }

        ///  
        /// Enumerates typefaces in the font location specified by a base URI and/or a location string.
        ///  
        /// Base URI used to determine the font location if the location parameter is not specified 
        /// or is relative, and the value of the BaseUri property of each FontFamily in the resulting collection. This
        /// parameter can be null if the location parameter specifies an absolute location. 
        /// Optional relative or absolute URI reference. The location is used (with baseUri) to
        /// determine the font folder and is exposed as part of the Source property of each FontFamily in the resulting
        /// collection. If location is null or empty then "./" is implied, meaning same folder as the base URI.
        /// Collection of Typeface objects from the specified font location. 
        /// 
        /// The caller must have FileIOPermission(FileIOPermissionAccess.Read) for the specified font folder. 
        /// Each resulting FontFamily object has the specified base Uri as its BaseUri property and includes the 
        /// specified location as part of the friendly name specified by the Source property.
        ///  
        public static ICollection GetTypefaces(Uri baseUri, string location)
        {
            return new TypefaceCollection(GetFontFamilies(baseUri, location));
        } 

        #endregion Public Methods 
 
        //------------------------------------------------------
        // 
        //  Public Properties
        //
        //-----------------------------------------------------
 
        #region Public Properties
 
        ///  
        /// Font families from the default system font location.
        ///  
        /// Collection of FontFamily objects from the default system font location.
        public static ICollection SystemFontFamilies
        {
            get 
            {
                return _defaultFontCollection; 
            } 
        }
 
        /// 
        /// Type faces from the default system font location.
        /// 
        /// Collection of Typeface objects from the default system font location. 
        public static ICollection SystemTypefaces
        { 
            get 
            {
                return new TypefaceCollection(_defaultFontCollection); 
            }
        }

 
        #endregion Public Properties
 
        //------------------------------------------------------ 
        //
        //  Private Methods 
        //
        //------------------------------------------------------

        #region Private Methods 

 
        ///  
        /// This method enumerates the font families in the specified font location and returns the resulting
        /// collection of FontFamily objects. 
        /// 
        /// Absolute URI of file or folder containing font data
        /// Optional base URI, exposed as the BaseUri property of each FontFamily.
        /// Optional location reference, exposed as part of the Source 
        /// property of each FontFamily.
        ///  
        /// SecurityCritical    - Calls the critical FamilyCollection constructor; fontLocation may be critical 
        /// TreatAsSafe         - FamilyCollection does security demands for the necessary permissions; fontLocation is
        ///                       not exposed by the resulting FontFamily objects 
        /// 
        [SecurityCritical,SecurityTreatAsSafe]
        private static ICollection CreateFamilyCollection(
            Uri     fontLocation, 
            Uri     fontFamilyBaseUri,
            string  fontFamilyLocationReference 
            ) 
        {
            // Use reference comparison to determine the critical isWindowsFonts value. We want this 
            // to be true ONLY if we're called internally to enumerate the default family collection.
            // See the SecurityNote for the FamilyCollection constructor.
            FamilyCollection familyCollection = new FamilyCollection(
                fontLocation, 
                object.ReferenceEquals(fontLocation, Util.WindowsFontsUriObject) // isWindowsFonts
                ); 
            CacheManager.Lookup(familyCollection); 

            FontFamily[] fontFamilyList = new FontFamily[familyCollection.FamilyCount]; 
            int i = 0;
            foreach (CachedFontFamily family in familyCollection.GetFontFamilies())
            {
                string fontFamilyReference = Util.ConvertFamilyNameAndLocationToFontFamilyReference( 
                    family.OrdinalName,
                    fontFamilyLocationReference 
                    ); 

                string friendlyName = Util.ConvertFontFamilyReferenceToFriendlyName(fontFamilyReference); 

                fontFamilyList[i++] = new FontFamily(fontFamilyBaseUri, friendlyName);
            }
            Debug.Assert(i == familyCollection.FamilyCount); 
            return Array.AsReadOnly(fontFamilyList);
        } 
 

        ///  
        /// Creates a collection of font families in the Windows Fonts folder.
        /// 
        /// 
        /// This method is used to initialized the static _defaultFontCollection field. By having this 
        /// safe wrapper for CreateFamilyCollection we avoid having to create a static initializer and
        /// declare it critical. 
        ///  
        /// 
        /// Critical    - This method accesses the critical Util.WindowsFontsUriObject 
        /// TreatAsSafe - It specifies null as the BaseUri of the resulting FontFamily objects
        /// 
        [SecurityCritical, SecurityTreatAsSafe]
        private static ICollection CreateDefaultFamilyCollection() 
        {
            return CreateFamilyCollection( 
                Util.WindowsFontsUriObject, // fontLocation 
                null,                       // fontFamilyBaseUri,
                null                        // fontFamilyLocationReference 
                );
        }

        #endregion Private Methods 

        //----------------------------------------------------- 
        // 
        //  Private Classes
        // 
        //------------------------------------------------------

        #region Private Classes
 
        private struct TypefaceCollection : ICollection
        { 
            private IEnumerable _families; 

            public TypefaceCollection(IEnumerable families) 
            {
                _families = families;
            }
 
            #region ICollection Members
 
            public void Add(Typeface item) 
            {
                throw new NotSupportedException(); 
            }

            public void Clear()
            { 
                throw new NotSupportedException();
            } 
 
            public bool Contains(Typeface item)
            { 
                foreach (Typeface t in this)
                {
                    if (t.Equals(item))
                        return true; 
                }
                return false; 
            } 

            public void CopyTo(Typeface[] array, int arrayIndex) 
            {
                if (array == null)
                {
                    throw new ArgumentNullException("array"); 
                }
 
                if (array.Rank != 1) 
                {
                    throw new ArgumentException(SR.Get(SRID.Collection_BadRank)); 
                }

                // The extra "arrayIndex >= array.Length" check in because even if _collection.Count
                // is 0 the index is not allowed to be equal or greater than the length 
                // (from the MSDN ICollection docs)
                if (arrayIndex < 0 || arrayIndex >= array.Length || (arrayIndex + Count) > array.Length) 
                { 
                    throw new ArgumentOutOfRangeException("arrayIndex");
                } 

                foreach (Typeface t in this)
                {
                    array[arrayIndex++] = t; 
                }
            } 
 
            public int Count
            { 
                get
                {
                    int count = 0;
                    foreach (Typeface t in this) 
                    {
                        ++count; 
                    } 
                    return count;
                } 
            }

            public bool IsReadOnly
            { 
                get
                { 
                    return true; 
                }
            } 

            public bool Remove(Typeface item)
            {
                throw new NotSupportedException(); 
            }
 
            #endregion 

            #region IEnumerable Members 

            public IEnumerator GetEnumerator()
            {
                foreach (FontFamily family in _families) 
                {
                    foreach (Typeface typeface in family.GetTypefaces()) 
                    { 
                        yield return typeface;
                    } 
                }
            }

            #endregion 

            #region IEnumerable Members 
 
            System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
            { 
                return ((IEnumerable)this).GetEnumerator();
            }

            #endregion 
        }
 
        #endregion Private Classes 

        //----------------------------------------------------- 
        //
        //  Private Fields
        //
        //----------------------------------------------------- 

        #region Private Fields 
 
        private static readonly ICollection _defaultFontCollection = CreateDefaultFamilyCollection();
 
        #endregion Private Fields
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
//---------------------------------------------------------------------------- 
//
// Copyright (c) Microsoft Corporation.  All rights reserved.
//
// Description: The Fonts class provides font enumeration APIs. 
//              See spec at http://avalon/text/DesignDocsAndSpecs/Font%20Enumeration%20API.htm
// 
// 
// History:
//  03/02/2004 : mleonov - Created 
//
//---------------------------------------------------------------------------

using System; 
using System.Text;
using System.IO; 
using System.Globalization; 
using System.Collections;
using System.Collections.Generic; 
using System.Diagnostics;
using System.Windows;

using MS.Internal; 
using MS.Internal.FontCache;
using MS.Internal.FontFace; 
using MS.Internal.PresentationCore; 
using MS.Internal.Shaping;
using System.Security; 

namespace System.Windows.Media
{
    ///  
    /// The FontEmbeddingManager class provides font enumeration APIs.
    ///  
    public static class Fonts 
    {
        //----------------------------------------------------- 
        //
        //  Public Methods
        //
        //----------------------------------------------------- 

        #region Public Methods 
 
        /// 
        /// Enumerates font families from an arbitrary location. 
        /// 
        /// An absolute URI of a folder containing fonts or a font file.
        /// Collection of FontFamily objects from the specified folder or file.
        ///  
        /// The specified location must be an absolute file URI or path, and the caller must have
        /// FileIOPermission(FileIOPermissionAccess.Read) for the location. Each resulting FontFamily 
        /// object includes the specified location in its friendly name and has no base URI. 
        /// 
        public static ICollection GetFontFamilies(string location) 
        {
            if (location == null)
                throw new ArgumentNullException("location");
 
            return GetFontFamilies(null, location);
        } 
 
        /// 
        /// Enumerates font families in the same folder as the specified base URI. 
        /// 
        /// An absolute URI of a folder containing fonts or a resource in that folder.
        /// Collection of FontFamily objects from the specified folder.
        ///  
        /// The caller must have FileIOPermission(FileIOPermissionAccess.Read) for the folder
        /// specified by baseUri. Each resulting FontFamily object has the specified Uri as its 
        /// BaseUri property has a friendly name of the form "./#Family Name". 
        /// 
        public static ICollection GetFontFamilies(Uri baseUri) 
        {
            if (baseUri == null)
                throw new ArgumentNullException("baseUri");
 
            return GetFontFamilies(baseUri, null);
        } 
 

        ///  
        /// Enumerates font families in the font location specified by a base URI and/or a location string.
        /// 
        /// Base URI used to determine the font location if the location parameter is not specified
        /// or is relative, and the value of the BaseUri property of each FontFamily in the resulting collection. This 
        /// parameter can be null if the location parameter specifies an absolute location.
        /// Optional relative or absolute URI reference. The location is used (with baseUri) to 
        /// determine the font folder and is exposed as part of the Source property of each FontFamily in the resulting 
        /// collection. If location is null or empty then "./" is implied, meaning same folder as the base URI.
        /// Collection of FontFamily objects from the specified font location. 
        /// 
        /// The caller must have FileIOPermission(FileIOPermissionAccess.Read) for the specified font folder.
        /// Each resulting FontFamily object has the specified base Uri as its BaseUri property and includes the
        /// specified location as part of the friendly name specified by the Source property. 
        /// 
        public static ICollection GetFontFamilies(Uri baseUri, string location) 
        { 
            // Both Uri parameters are optional but neither can be relative.
            if (baseUri != null && !baseUri.IsAbsoluteUri) 
                throw new ArgumentException(SR.Get(SRID.UriNotAbsolute), "baseUri");

            // Determine the font location from the base URI and location string.
            Uri fontLocation; 
            if (!string.IsNullOrEmpty(location) && Uri.TryCreate(location, UriKind.Absolute, out fontLocation))
            { 
                // absolute location; make sure we support absolute font family references for this scheme 
                if (!Util.IsSupportedSchemeForAbsoluteFontFamilyUri(fontLocation))
                    throw new ArgumentException(SR.Get(SRID.InvalidAbsoluteUriInFontFamilyName), "location"); 

                // make sure the absolute location is a valid URI reference rather than a Win32 path as
                // we don't support the latter in a font family reference
                location = fontLocation.GetComponents(UriComponents.AbsoluteUri, UriFormat.SafeUnescaped); 
            }
            else 
            { 
                // relative location; we need a base URI
                if (baseUri == null) 
                    throw new ArgumentNullException("baseUri", SR.Get(SRID.NullBaseUriParam, "baseUri", "location"));

                // the location part must include a path component, otherwise we'll look in windows fonts and ignore the base URI
                if (string.IsNullOrEmpty(location)) 
                    location = "./";
                else if (Util.IsReferenceToWindowsFonts(location)) 
                    location = "./" + location; 

                fontLocation = new Uri(baseUri, location); 
            }

            // Create the font families.
            return CreateFamilyCollection( 
                fontLocation,   // fontLocation
                baseUri,        // fontFamilyBaseUri 
                location        // fontFamilyLocationReference 
                );
        } 


        /// 
        /// Enumerates typefaces from an arbitrary location. 
        /// 
        /// An absolute URI of a folder containing fonts or a font file. 
        /// Collection of Typeface objects from the specified folder or file. 
        /// 
        /// The specified location must be an absolute file URI or path, and the caller must have 
        /// FileIOPermission(FileIOPermissionAccess.Read) for the location. The FontFamily of each
        /// resulting Typeface object includes the specified location in its friendly name and has
        /// no base URI.
        ///  
        public static ICollection GetTypefaces(string location)
        { 
            if (location == null) 
                throw new ArgumentNullException("location");
 
            return new TypefaceCollection(GetFontFamilies(null, location));
        }

        ///  
        /// Enumerates typefaces in the same folder as the specified base URI.
        ///  
        /// An absolute URI of a folder containing fonts or a resource in that folder. 
        /// Collection of Typeface objects from the specified folder.
        ///  
        /// The caller must have FileIOPermission(FileIOPermissionAccess.Read) for the folder
        /// specified by baseUri. The FontFamily of each resulting Typeface object has the specified
        /// Uri as its BaseUri property has a friendly name of the form "./#Family Name".
        ///  
        public static ICollection GetTypefaces(Uri baseUri)
        { 
            if (baseUri == null) 
                throw new ArgumentNullException("baseUri");
 
            return new TypefaceCollection(GetFontFamilies(baseUri, null));
        }

        ///  
        /// Enumerates typefaces in the font location specified by a base URI and/or a location string.
        ///  
        /// Base URI used to determine the font location if the location parameter is not specified 
        /// or is relative, and the value of the BaseUri property of each FontFamily in the resulting collection. This
        /// parameter can be null if the location parameter specifies an absolute location. 
        /// Optional relative or absolute URI reference. The location is used (with baseUri) to
        /// determine the font folder and is exposed as part of the Source property of each FontFamily in the resulting
        /// collection. If location is null or empty then "./" is implied, meaning same folder as the base URI.
        /// Collection of Typeface objects from the specified font location. 
        /// 
        /// The caller must have FileIOPermission(FileIOPermissionAccess.Read) for the specified font folder. 
        /// Each resulting FontFamily object has the specified base Uri as its BaseUri property and includes the 
        /// specified location as part of the friendly name specified by the Source property.
        ///  
        public static ICollection GetTypefaces(Uri baseUri, string location)
        {
            return new TypefaceCollection(GetFontFamilies(baseUri, location));
        } 

        #endregion Public Methods 
 
        //------------------------------------------------------
        // 
        //  Public Properties
        //
        //-----------------------------------------------------
 
        #region Public Properties
 
        ///  
        /// Font families from the default system font location.
        ///  
        /// Collection of FontFamily objects from the default system font location.
        public static ICollection SystemFontFamilies
        {
            get 
            {
                return _defaultFontCollection; 
            } 
        }
 
        /// 
        /// Type faces from the default system font location.
        /// 
        /// Collection of Typeface objects from the default system font location. 
        public static ICollection SystemTypefaces
        { 
            get 
            {
                return new TypefaceCollection(_defaultFontCollection); 
            }
        }

 
        #endregion Public Properties
 
        //------------------------------------------------------ 
        //
        //  Private Methods 
        //
        //------------------------------------------------------

        #region Private Methods 

 
        ///  
        /// This method enumerates the font families in the specified font location and returns the resulting
        /// collection of FontFamily objects. 
        /// 
        /// Absolute URI of file or folder containing font data
        /// Optional base URI, exposed as the BaseUri property of each FontFamily.
        /// Optional location reference, exposed as part of the Source 
        /// property of each FontFamily.
        ///  
        /// SecurityCritical    - Calls the critical FamilyCollection constructor; fontLocation may be critical 
        /// TreatAsSafe         - FamilyCollection does security demands for the necessary permissions; fontLocation is
        ///                       not exposed by the resulting FontFamily objects 
        /// 
        [SecurityCritical,SecurityTreatAsSafe]
        private static ICollection CreateFamilyCollection(
            Uri     fontLocation, 
            Uri     fontFamilyBaseUri,
            string  fontFamilyLocationReference 
            ) 
        {
            // Use reference comparison to determine the critical isWindowsFonts value. We want this 
            // to be true ONLY if we're called internally to enumerate the default family collection.
            // See the SecurityNote for the FamilyCollection constructor.
            FamilyCollection familyCollection = new FamilyCollection(
                fontLocation, 
                object.ReferenceEquals(fontLocation, Util.WindowsFontsUriObject) // isWindowsFonts
                ); 
            CacheManager.Lookup(familyCollection); 

            FontFamily[] fontFamilyList = new FontFamily[familyCollection.FamilyCount]; 
            int i = 0;
            foreach (CachedFontFamily family in familyCollection.GetFontFamilies())
            {
                string fontFamilyReference = Util.ConvertFamilyNameAndLocationToFontFamilyReference( 
                    family.OrdinalName,
                    fontFamilyLocationReference 
                    ); 

                string friendlyName = Util.ConvertFontFamilyReferenceToFriendlyName(fontFamilyReference); 

                fontFamilyList[i++] = new FontFamily(fontFamilyBaseUri, friendlyName);
            }
            Debug.Assert(i == familyCollection.FamilyCount); 
            return Array.AsReadOnly(fontFamilyList);
        } 
 

        ///  
        /// Creates a collection of font families in the Windows Fonts folder.
        /// 
        /// 
        /// This method is used to initialized the static _defaultFontCollection field. By having this 
        /// safe wrapper for CreateFamilyCollection we avoid having to create a static initializer and
        /// declare it critical. 
        ///  
        /// 
        /// Critical    - This method accesses the critical Util.WindowsFontsUriObject 
        /// TreatAsSafe - It specifies null as the BaseUri of the resulting FontFamily objects
        /// 
        [SecurityCritical, SecurityTreatAsSafe]
        private static ICollection CreateDefaultFamilyCollection() 
        {
            return CreateFamilyCollection( 
                Util.WindowsFontsUriObject, // fontLocation 
                null,                       // fontFamilyBaseUri,
                null                        // fontFamilyLocationReference 
                );
        }

        #endregion Private Methods 

        //----------------------------------------------------- 
        // 
        //  Private Classes
        // 
        //------------------------------------------------------

        #region Private Classes
 
        private struct TypefaceCollection : ICollection
        { 
            private IEnumerable _families; 

            public TypefaceCollection(IEnumerable families) 
            {
                _families = families;
            }
 
            #region ICollection Members
 
            public void Add(Typeface item) 
            {
                throw new NotSupportedException(); 
            }

            public void Clear()
            { 
                throw new NotSupportedException();
            } 
 
            public bool Contains(Typeface item)
            { 
                foreach (Typeface t in this)
                {
                    if (t.Equals(item))
                        return true; 
                }
                return false; 
            } 

            public void CopyTo(Typeface[] array, int arrayIndex) 
            {
                if (array == null)
                {
                    throw new ArgumentNullException("array"); 
                }
 
                if (array.Rank != 1) 
                {
                    throw new ArgumentException(SR.Get(SRID.Collection_BadRank)); 
                }

                // The extra "arrayIndex >= array.Length" check in because even if _collection.Count
                // is 0 the index is not allowed to be equal or greater than the length 
                // (from the MSDN ICollection docs)
                if (arrayIndex < 0 || arrayIndex >= array.Length || (arrayIndex + Count) > array.Length) 
                { 
                    throw new ArgumentOutOfRangeException("arrayIndex");
                } 

                foreach (Typeface t in this)
                {
                    array[arrayIndex++] = t; 
                }
            } 
 
            public int Count
            { 
                get
                {
                    int count = 0;
                    foreach (Typeface t in this) 
                    {
                        ++count; 
                    } 
                    return count;
                } 
            }

            public bool IsReadOnly
            { 
                get
                { 
                    return true; 
                }
            } 

            public bool Remove(Typeface item)
            {
                throw new NotSupportedException(); 
            }
 
            #endregion 

            #region IEnumerable Members 

            public IEnumerator GetEnumerator()
            {
                foreach (FontFamily family in _families) 
                {
                    foreach (Typeface typeface in family.GetTypefaces()) 
                    { 
                        yield return typeface;
                    } 
                }
            }

            #endregion 

            #region IEnumerable Members 
 
            System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
            { 
                return ((IEnumerable)this).GetEnumerator();
            }

            #endregion 
        }
 
        #endregion Private Classes 

        //----------------------------------------------------- 
        //
        //  Private Fields
        //
        //----------------------------------------------------- 

        #region Private Fields 
 
        private static readonly ICollection _defaultFontCollection = CreateDefaultFamilyCollection();
 
        #endregion Private Fields
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
                        

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