TextLine.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Core / System / Windows / Media / textformatting / TextLine.cs / 1 / TextLine.cs
                        
                        
                            //------------------------------------------------------------------------ 
//
//  Microsoft Windows Client Platform
//  Copyright (C) Microsoft Corporation
// 
//  File:      TextLine.cs
// 
//  Contents:  Text line API 
//
//  Spec:      [....]/sites/Avalon/Specs/Text%20Formatting%20API.doc 
//
//  Created:   2-25-2003 [....] ([....])
//
//----------------------------------------------------------------------- 

 
using System; 
using System.Collections;
using System.Collections.Generic; 
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Media;
using MS.Internal.TextFormatting; 
using MS.Internal.PresentationCore;
 
 
namespace System.Windows.Media.TextFormatting
{ 
    /// 
    /// Once a line is complete, FormatLine returns a TextLine object to the client.
    /// The text layout client may then use the TextLines measurement and drawing methods.
    ///  
    public abstract class TextLine : ITextMetrics, IDisposable
    { 
        ///  
        /// Clean up text line internal resource
        ///  
        public abstract void Dispose();


        ///  
        /// Client to draw the line
        ///  
        /// drawing context 
        /// drawing origin
        /// indicate the inversion of the drawing surface 
        public abstract void Draw(
            DrawingContext      drawingContext,
            Point               origin,
            InvertAxes          inversion 
            );
 
 
        /// 
        /// Client to collapse the line and get a collapsed line that fits for display 
        /// 
        /// a list of collapsing properties
        public abstract TextLine Collapse(
            params TextCollapsingProperties[]   collapsingPropertiesList 
            );
 
 
        /// 
        /// Client to get a collection of collapsed characer ranges after a line has been collapsed 
        /// 
        public abstract IList GetTextCollapsedRanges();

 
        /// 
        /// Client to get the character hit corresponding to the specified 
        /// distance from the beginning of the line. 
        /// 
        /// distance in text flow direction from the beginning of the line 
        /// character hit
        public abstract CharacterHit GetCharacterHitFromDistance(
            double      distance
            ); 

 
        ///  
        /// Client to get the distance from the beginning of the line from the specified
        /// character hit. 
        /// 
        /// character hit of the character to query the distance.
        /// distance in text flow direction from the beginning of the line.
        public abstract double GetDistanceFromCharacterHit( 
            CharacterHit    characterHit
            ); 
 

        ///  
        /// Client to get the next character hit for caret navigation
        /// 
        /// the current character hit
        /// the next character hit 
        public abstract CharacterHit GetNextCaretCharacterHit(
            CharacterHit    characterHit 
            ); 

 
        /// 
        /// Client to get the previous character hit for caret navigation
        /// 
        /// the current character hit 
        /// the previous character hit
        public abstract CharacterHit GetPreviousCaretCharacterHit( 
            CharacterHit    characterHit 
            );
 

        /// 
        /// Client to get the previous character hit after backspacing
        ///  
        /// the current character hit
        /// the character hit after backspacing 
        public abstract CharacterHit GetBackspaceCaretCharacterHit( 
            CharacterHit    characterHit
            ); 


        /// 
        /// Determine whether the input character hit is a valid caret stop. 
        /// 
        /// the current character hit 
        /// the starting cp index of the line 
        /// 
        /// It is used by Framework to iterate through each codepoint in the line to 
        /// see if the code point is a caret stop. In general, the leading edge of
        /// codepoint is a valid caret stop if moving forward and then backward will
        /// return back to it,  vice versa for the trailing edge of a codepoint.
        ///  
        [FriendAccessAllowed]
        internal bool IsAtCaretCharacterHit(CharacterHit characterHit, int cpFirst) 
        { 
            // TrailingLength is used as a flag to indicate whether the character
            // hit is on the leading or trailing edge of the character. 
            if (characterHit.TrailingLength == 0)
            {
                CharacterHit nextHit = GetNextCaretCharacterHit(characterHit);
                if (nextHit == characterHit) 
                {
                    // At this point we only know that no caret stop is available 
                    // after the input, we caliberate the input to the end of the line. 
                    nextHit = new CharacterHit(cpFirst + Length - 1, 1);
                } 

                CharacterHit previousHit = GetPreviousCaretCharacterHit(nextHit);
                return previousHit == characterHit;
            } 
            else
            { 
                CharacterHit previousHit = GetPreviousCaretCharacterHit(characterHit); 
                CharacterHit nextHit     = GetNextCaretCharacterHit(previousHit);
                return nextHit == characterHit; 
            }
        }

 

        ///  
        /// Client to get an array of bounding rectangles of a range of characters within a text line. 
        /// 
        /// index of first character of specified range 
        /// number of characters of the specified range
        /// an array of bounding rectangles.
        public abstract IList GetTextBounds(
            int     firstTextSourceCharacterIndex, 
            int     textLength
            ); 
 

        ///  
        /// Client to get a collection of TextRun span objects within a line
        /// 
        public abstract IList> GetTextRunSpans();
 

        ///  
        /// Client to get IndexedGlyphRuns enumerable to enumerate each IndexedGlyphRun object 
        /// in the line. Through IndexedGlyphRun client can obtain glyph information of
        /// a text source character. 
        /// 
        public abstract IEnumerable GetIndexedGlyphRuns();

 
        /// 
        /// Client to get a boolean value indicates whether content of the line overflows 
        /// the specified paragraph width. 
        /// 
        public abstract bool HasOverflowed 
        { get; }


        ///  
        /// Client to get a boolean value indicates whether a line has been collapsed
        ///  
        public abstract bool HasCollapsed 
        { get; }
 

        /// 
        /// Client to get a Boolean flag indicating whether the line is truncated in the
        /// middle of a word. This flag is set only when TextParagraphProperties.TextWrapping 
        /// is set to TextWrapping.Wrap and a single word is longer than the formatting
        /// paragraph width. In such situation, TextFormatter truncates the line in the middle 
        /// of the word to honor the desired behavior specified by TextWrapping.Wrap setting. 
        /// 
        public virtual bool IsTruncated 
        {
            get { return false; }
        }
 

        ///  
        /// Client to acquire a state at the point where line is broken by line breaking process; 
        /// can be null when the line ends by the ending of the paragraph. Client may pass this
        /// value back to TextFormatter as an input argument to TextFormatter.FormatLine when 
        /// formatting the next line within the same paragraph.
        /// 
        public abstract TextLineBreak GetTextLineBreak();
 
        #region ITextMetrics
 
        ///  
        /// Client to get the number of text source positions of this line
        ///  
        public abstract int Length
        { get; }

 
        /// 
        /// Client to get the number of whitespace characters at the end of the line. 
        ///  
        public abstract int TrailingWhitespaceLength
        { get; } 


        /// 
        /// Client to get the number of characters following the last character 
        /// of the line that may trigger reformatting of the current line.
        ///  
        public abstract int DependentLength 
        { get; }
 

        /// 
        /// Client to get the number of newline characters at line end
        ///  
        public abstract int NewlineLength
        { get; } 
 

        ///  
        /// Client to get distance from paragraph start to line start
        /// 
        public abstract double Start
        { get; } 

 
        ///  
        /// Client to get the total width of this line
        ///  
        public abstract double Width
        { get; }

 
        /// 
        /// Client to get the total width of this line including width of whitespace characters at the end of the line. 
        ///  
        public abstract double WidthIncludingTrailingWhitespace
        { get; } 


        /// 
        /// Client to get the height of the line 
        /// 
        public abstract double Height 
        { get; } 

 
        /// 
        /// Client to get the height of the text (or other content) in the line; this property may differ from the Height
        /// property if the client specified the line height
        ///  
        public abstract double TextHeight
        { get; } 
 

        ///  
        /// Client to get the height of the actual black of the line
        /// 
        public abstract double Extent
        { get; } 

 
        ///  
        /// Client to get the distance from top to baseline of this text line
        ///  
        public abstract double Baseline
        { get; }

 
        /// 
        /// Client to get the distance from the top of the text (or other content) to the baseline of this text line; 
        /// this property may differ from the Baseline property if the client specified the line height 
        /// 
        public abstract double TextBaseline 
        { get; }


        ///  
        /// Client to get the distance from the before edge of line height
        /// to the baseline of marker of the line if any. 
        ///  
        public abstract double MarkerBaseline
        { get; } 


        /// 
        /// Client to get the overall height of the list items marker of the line if any. 
        /// 
        public abstract double MarkerHeight 
        { get; } 

 
        /// 
        /// Client to get the distance covering all black preceding the leading edge of the line.
        /// 
        public abstract double OverhangLeading 
        { get; }
 
 
        /// 
        /// Client to get the distance covering all black following the trailing edge of the line. 
        /// 
        public abstract double OverhangTrailing
        { get; }
 

        ///  
        /// Client to get the distance from the after edge of line height to the after edge of the extent of the line. 
        /// 
        public abstract double OverhangAfter 
        { get; }
        #endregion
    }
 

    ///  
    /// Indicate the inversion of axes of the drawing surface 
    /// 
    [Flags] 
    public enum InvertAxes
    {
        /// 
        /// Drawing surface is not inverted in either axis 
        /// 
        None = 0, 
 
        /// 
        /// Drawing surface is inverted in horizontal axis 
        /// 
        Horizontal = 1,

        ///  
        /// Drawing surface is inverted in vertical axis
        ///  
        Vertical = 2, 

        ///  
        /// Drawing surface is inverted in both axes
        /// 
        Both = (Horizontal | Vertical),
    } 
}

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