DrawingState.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Core / CSharp / MS / Internal / TextFormatting / DrawingState.cs / 1305600 / DrawingState.cs
                        
                        
                            //------------------------------------------------------------------------ 
//
//  Microsoft Windows Client Platform
//  Copyright (C) Microsoft Corporation
// 
//  File:      DrawingState.cs
// 
//  Contents:  Drawing state of full text 
//
//  Created:   1-29-2005 Worachai Chaoweeraprasit (wchao) 
//
//-----------------------------------------------------------------------

 
using System;
using System.Diagnostics; 
using System.Windows; 
using System.Windows.Media;
 

namespace MS.Internal.TextFormatting
{
    ///  
    /// Formatting state of full text
    ///  
    internal sealed class DrawingState : IDisposable 
    {
        private TextMetrics.FullTextLine    _currentLine;               // full text line currently formatted 
        private DrawingContext              _drawingContext;            // current drawing context
        private Point                       _lineOrigin;                // line origin XY relative to drawing context reference location
        private Point                       _vectorToLineOrigin;        // vector to line origin in UV relative to paragraph start
        private MatrixTransform             _antiInversion;             // anti-inversion transform applied on drawing surface 
        private bool                        _overrideBaseGuidelineY;    // a flag indicating whether a new guideline overrides the line's Y guideline
        private double                      _baseGuidelineY;            // the Y guideline of the text line. 
 
        /// 
        /// Construct drawing state for full text 
        /// 
        internal DrawingState(
            DrawingContext                  drawingContext,
            Point                           lineOrigin, 
            MatrixTransform                 antiInversion,
            TextMetrics.FullTextLine        currentLine 
            ) 
        {
            _drawingContext = drawingContext; 
            _antiInversion = antiInversion;
            _currentLine = currentLine;

            if (antiInversion == null) 
            {
                _lineOrigin = lineOrigin; 
            } 
            else
            { 
                _vectorToLineOrigin = lineOrigin;
            }

            if (_drawingContext != null) 
            {
                // LineServices draws GlyphRun and TextDecorations in multiple 
                // callbacks and GlyphRuns may have different baselines. Pushing guideline 
                // for each DrawGlyphRun are too costly. We optimize for the common case where
                // GlyphRuns and TextDecorations in the TextLine share the same baseline. 
                _baseGuidelineY = lineOrigin.Y + currentLine.Baseline;

                _drawingContext.PushGuidelineY1(_baseGuidelineY);
            } 
        }
 
        ///  
        /// Set guideline Y for a drawing operation if necessary. It is a no-op if the Y value is the same
        /// as the guideline Y of the line. Otherwise, it will push the Y to override the guideline of the line. 
        /// A SetGuidelineY() must be paired with an UnsetGuidelineY() to ensure balanced push and pop.
        /// 
        internal void SetGuidelineY(double runGuidelineY)
        { 
            if (_drawingContext == null)
                return; 
 
            Invariant.Assert(!_overrideBaseGuidelineY);
 
            if (runGuidelineY != _baseGuidelineY)
            {
                // Push a new guideline to override the line's guideline
                _drawingContext.PushGuidelineY1(runGuidelineY); 

                _overrideBaseGuidelineY = true; // the new Guideline Y overrides the line's guideline until next unset. 
            } 
        }
 
        /// 
        /// Unset guideline Y for a drawing operation if necessary. It is a no-op if the Y value is the same
        /// as the guideline Y of the line. Otherwise, it will push the Y to override the guideline of the line.
        /// A SetGuidelineY() must be paired with an UnsetGuidelineY() to ensure balanced push and pop. 
        /// 
        internal void UnsetGuidelineY() 
        { 
            if (_overrideBaseGuidelineY)
            { 
                _drawingContext.Pop();
                _overrideBaseGuidelineY = false;
            }
        } 

        ///  
        /// Clean up internal state. 
        /// 
        public void Dispose() 
        {
            // clear the guideline at line's baseline
            if (_drawingContext != null)
            { 
                _drawingContext.Pop();
            } 
        } 

 
        /// 
        /// Current drawing context
        /// 
        internal DrawingContext DrawingContext 
        {
            get { return _drawingContext; } 
        } 

 
        /// 
        /// Anti-inversion transform applied on drawing surface
        /// 
        internal MatrixTransform AntiInversion 
        {
            get { return _antiInversion; } 
        } 

 
        /// 
        /// Origin XY of the current line relative to the drawing context reference location
        /// 
        internal Point LineOrigin 
        {
            get { return _lineOrigin; } 
        } 

 
        /// 
        /// Vector to line origin in UV relative to paragraph start
        /// 
        internal Point VectorToLineOrigin 
        {
            get { return _vectorToLineOrigin; } 
        } 

 
        /// 
        /// Line currently being drawn
        /// 
        internal TextMetrics.FullTextLine CurrentLine 
        {
            get { return _currentLine; } 
        } 
    }
} 

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