TextEffectResolver.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Framework / System / Windows / Documents / TextEffectResolver.cs / 1 / TextEffectResolver.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
// 
// Description: Text Effect Setter 
//
// History: 
//  3/24/2004  [....] Created
//  10/28/2004 [....] rewrite the helper class
//
//--------------------------------------------------------------------------- 

using System.Collections.Generic; 
 
using System.Windows.Controls;
using System.Windows.Documents; 
using System.Windows.Media;

using MS.Internal.Text;
 
namespace System.Windows.Documents
{ 
    ///  
    /// Helper class to help set text effects into the Text container
    ///  
    public static class TextEffectResolver
    {

        //--------------------------- 
        // public static methods
        //--------------------------- 
 
        /// 
        /// resolves text effect on a text range to a list of text effect targets. 
        /// The method will walk the text and perform the following task:
        /// 1) For each continous block of text, create a text effect targeting the scoping element
        /// 2) For the text effect created, calculate the starting cp index and cp count for the effect
        /// 
        /// The method will create freezable copy of the TextEffect passed in and fill in
        /// CharacterIndex and Count for the range. 
        ///  
        /// starting text pointer
        /// end text pointer 
        /// effect that is apply on the text
        public static TextEffectTarget[] Resolve(
            TextPointer             startPosition,
            TextPointer             endPosition, 
            TextEffect              effect
            ) 
        { 
            if (effect == null)
                throw new ArgumentNullException("effect"); 

            ValidationHelper.VerifyPositionPair(startPosition, endPosition);
            TextPointer   effectStart   = new TextPointer(startPosition);
 
            // move to the first character symbol at or after Start position
            MoveToFirstCharacterSymbol(effectStart); 
 
            TextEffect effectCopy;
            List list = new List(); 

            // we will now traverse the TOM and resolve text effects to the immediate parent
            // of the characters. We are effectively applying the text effect onto
            // block of continous text. 
            while (effectStart.CompareTo(endPosition) < 0)
            { 
                // create a copy of the text effect 
                // so that we can set the CharacterIndex and Count
                effectCopy                 = effect.Clone(); 

                // create a position
                TextPointer continuousTextEnd = new TextPointer(effectStart);
 
                // move the position to the end of the continuous text block
                MoveToFirstNonCharacterSymbol(continuousTextEnd, endPosition); 
 
                // make sure we are not out of the range
                continuousTextEnd = (TextPointer)TextPointerBase.Min(continuousTextEnd, endPosition); 

                // set the character index to be the distance from the Start
                // of this text block to the Start of the text container
                effectCopy.PositionStart = effectStart.TextContainer.Start.GetOffsetToPosition(effectStart); 

                // count is the distance from the text block start to end 
                effectCopy.PositionCount = effectStart.GetOffsetToPosition(continuousTextEnd); 

                list.Add( 
                    new TextEffectTarget(
                        effectStart.Parent,
                        effectCopy
                        ) 
                 );
 
                // move the effectStart to the beginning of the next text block. 
                effectStart = continuousTextEnd;
                MoveToFirstCharacterSymbol(effectStart); 
            }

            return list.ToArray();
        } 

 
        //--------------------------- 
        // Private static methods
        //--------------------------- 

        // move to the first character symbol
        private static void MoveToFirstCharacterSymbol(TextPointer navigator)
        { 
            while (navigator.GetPointerContext(LogicalDirection.Forward) != TextPointerContext.Text
                && navigator.MoveToNextContextPosition(LogicalDirection.Forward)) ; 
        } 

        // move to the first non-character symbol, but not pass beyond the limit 
        private static void MoveToFirstNonCharacterSymbol(
            TextPointer navigator,   // navigator to move
            TextPointer  stopHint     // don't move further if we already pass beyond this point
            ) 
        {
            while (navigator.GetPointerContext(LogicalDirection.Forward) == TextPointerContext.Text 
                && navigator.CompareTo(stopHint) < 0 
                && navigator.MoveToNextContextPosition(LogicalDirection.Forward)) ;
        } 
    }

    /// 
    /// result from TextEffectSetter which contains the TextEffect created and the DependencyObject 
    /// to which the TextEffect should be set.
    ///  
    public class TextEffectTarget 
    {
        private DependencyObject   _element; 
        private TextEffect         _effect;

        internal TextEffectTarget(
            DependencyObject element, 
            TextEffect       effect
            ) 
        { 
            if (element == null)
                throw new ArgumentNullException("element"); 

            if (effect == null)
                throw new ArgumentNullException("effect");
 
            _element = element;
            _effect  = effect; 
        } 

        ///  
        /// The DependencyObject that the TextEffect is targetting.
        /// 
        public DependencyObject Element
        { 
            get { return _element; }
        } 
 
        /// 
        /// The TextEffect 
        /// 
        public TextEffect TextEffect
        {
            get { return _effect; } 
        }
 
        ///  
        /// Enable the TextEffect on the target. If the texteffect is
        /// already enabled, this will be a no-op. 
        /// 
        public void Enable()
        {
            TextEffectCollection textEffects = DynamicPropertyReader.GetTextEffects(_element); 
            if (textEffects == null)
            { 
                textEffects = new TextEffectCollection(); 

                // use it as reference to avoid creating a copy (Freezable pattern) 
                _element.SetValue(TextElement.TextEffectsProperty, textEffects);
            }

 
            // check whether this instance is already enabled
            for (int i = 0; i < textEffects.Count; i++) 
            { 
                if (textEffects[i] == _effect)
                    return; // no-op 
            }

            // use this as reference.
            textEffects.Add(_effect); 
        }
 
        ///  
        /// Disable TextEffect on the target. If the texteffect is
        /// already disabled, this will be a no-op. 
        /// 
        public void Disable()
        {
            TextEffectCollection textEffects = DynamicPropertyReader.GetTextEffects(_element); 

            if (textEffects != null) 
            { 
                for (int i = 0; i < textEffects.Count; i++)
                { 
                    if (textEffects[i] == _effect)
                    {
                        // remove the exact instance of the effect from the collection
                        textEffects.RemoveAt(i); 
                        return;
                    } 
                } 
            }
        } 

        /// 
        /// Return whether the text effect is enabled on the target element
        ///  
        public bool IsEnabled
        { 
            get 
            {
                TextEffectCollection textEffects = DynamicPropertyReader.GetTextEffects(_element); 
                if (textEffects != null)
                {
                    for (int i = 0; i < textEffects.Count; i++)
                    { 
                        if (textEffects[i] == _effect)
                        { 
                           return true; 
                        }
                    } 
                }

                return false;
            } 

        } 
 

    } 
}


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

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