GlyphingCache.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Core / MS / Internal / Shaping / GlyphingCache.cs / 1 / GlyphingCache.cs
                        

                        
                            //---------------------------------------------------------------------------- 
//
// Copyright (c) Microsoft Corporation.  All rights reserved.
//
// Description: High level glyphing cache 
//
// History: 5-19-2005 [....] created 
// 
//---------------------------------------------------------------------------
 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Globalization; 
using System.Windows.Media;
using System.Windows.Media.TextFormatting; 
 
using MS.Internal;
using MS.Internal.TextFormatting; 

namespace MS.Internal.Shaping
{
    ///  
    /// GlyphingCache stores the runtime state of shaping engines and the mapping between Unicode scalar
    /// value and the physical font being used to display it. This class is not thread-safe. The client is 
    /// responsible for synchronizing access from multiple threads. It is generally recommended that the client 
    /// manages a single instance of this class per text formatting session.
    /// 
    /// It currently only caches one key-value pair:
    /// o Typeface - TypefaceMap
    ///
    /// This pair is cached in SizeLimitedCache which implement LRU algorithm through 
    /// a linked list. When cache is full, the least used entry in the cache will be replaced
    /// by the latest entry. 
    ///  
    internal class GlyphingCache
    { 
        private SizeLimitedCache  _sizeLimitedCache;
        private ShapingEngineManager _shapeManager;

        internal GlyphingCache(int capacity) 
        {
            _sizeLimitedCache  = new SizeLimitedCache(capacity); 
            _shapeManager      = new ShapingEngineManager(); 
        }
 
        internal void GetShapeableText(
            Typeface                    typeface,
            CharacterBufferReference    characterBufferReference,
            int                         stringLength, 
            TextRunProperties           textRunProperties,
            CultureInfo                 digitCulture, 
            bool                        rightToLeft, 
            IList shapeableList,
            IShapeableTextCollector     collector 
            )
        {
            if (!typeface.Symbol)
            { 
                Lookup(typeface).GetShapeableText(
                    characterBufferReference, 
                    stringLength, 
                    textRunProperties,
                    digitCulture, 
                    rightToLeft,
                    shapeableList,
                    collector
                    ); 
            }
            else 
            { 
                // It's a non-Unicode ("symbol") font, where code points have non-standard meanings. We
                // therefore want to bypass the usual itemization and font linking. Instead, just map 
                // everything to the default script and first GlyphTypeface.

                ShapeTypeface shapeTypeface = new ShapeTypeface(
                    _shapeManager, 
                    typeface.TryGetGlyphTypeface(),
                    null // device font 
                    ); 

                collector.Add( 
                    shapeableList,
                    new CharacterBufferRange(characterBufferReference, stringLength),
                    textRunProperties,
                    new Item(ScriptID.Default, ItemFlags.Default), 
                    shapeTypeface,
                    1.0,   // scale in Em 
                    false  // null shape 
                    );
            } 
        }

        /// 
        /// Look up the font mapping data for a typeface. 
        /// 
        private TypefaceMap Lookup(Typeface key) 
        { 
            TypefaceMap typefaceMap = _sizeLimitedCache.Get(key);
            if (typefaceMap == null) 
            {
                typefaceMap = new TypefaceMap(
                    key.FontFamily,
                    key.FallbackFontFamily, 
                    key.CanonicalStyle,
                    key.CanonicalWeight, 
                    key.CanonicalStretch, 
                    key.NullFont,
                    _shapeManager 
                    );

                _sizeLimitedCache.Add(
                    key, 
                    typefaceMap,
                    false   // is not permanent in the cache. 
                    ); 
            }
 
            return typefaceMap;
        }
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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