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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
//
//
// Contents: Drawing state of full text
//
//
using System;
using System.Diagnostics;
using System.Windows;
using System.Windows.Media;
namespace MS.Internal.TextFormatting
{
/// <summary>
/// Formatting state of full text
/// </summary>
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.
/// <summary>
/// Construct drawing state for full text
/// </summary>
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);
}
}
/// <summary>
/// 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.
/// </summary>
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.
}
}
/// <summary>
/// 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.
/// </summary>
internal void UnsetGuidelineY()
{
if (_overrideBaseGuidelineY)
{
_drawingContext.Pop();
_overrideBaseGuidelineY = false;
}
}
/// <summary>
/// Clean up internal state.
/// </summary>
public void Dispose()
{
// clear the guideline at line's baseline
if (_drawingContext != null)
{
_drawingContext.Pop();
}
}
/// <summary>
/// Current drawing context
/// </summary>
internal DrawingContext DrawingContext
{
get { return _drawingContext; }
}
/// <summary>
/// Anti-inversion transform applied on drawing surface
/// </summary>
internal MatrixTransform AntiInversion
{
get { return _antiInversion; }
}
/// <summary>
/// Origin XY of the current line relative to the drawing context reference location
/// </summary>
internal Point LineOrigin
{
get { return _lineOrigin; }
}
/// <summary>
/// Vector to line origin in UV relative to paragraph start
/// </summary>
internal Point VectorToLineOrigin
{
get { return _vectorToLineOrigin; }
}
/// <summary>
/// Line currently being drawn
/// </summary>
internal TextMetrics.FullTextLine CurrentLine
{
get { return _currentLine; }
}
}
}
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