|
// 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.
using System;
using System.Collections;
using System.Globalization;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.TextFormatting;
namespace MS.Internal.Text
{
/// <summary>
/// TextModifier that can modify properties of a text span.
/// It supports modifying TextDecorations and bid embedding levels
/// over a span of runs.
/// </summary>
internal class TextSpanModifier : TextModifier
{
private int _length;
private TextDecorationCollection _modifierDecorations;
private Brush _modifierBrush;
private FlowDirection _flowDirection;
private bool _hasDirectionalEmbedding;
/// <summary>
/// Creates a TextSpanModifier with the specified length and
/// properties to modify TextDecorations.
/// Instance created will not affect bidi embedding level.
/// </summary>
public TextSpanModifier(int length, TextDecorationCollection textDecorations, Brush foregroundBrush)
{
_length = length;
_modifierDecorations = textDecorations;
_modifierBrush = foregroundBrush;
}
/// <summary>
/// Creates a TextSpanModifier with the specified length and
/// properties. Instance created will modify Bidi embedding level. It will also modify TextDecorations if the
/// input TextDecorations is not null.
/// </summary>
public TextSpanModifier(int length, TextDecorationCollection textDecorations, Brush foregroundBrush, FlowDirection flowDirection)
: this (length, textDecorations, foregroundBrush)
{
_hasDirectionalEmbedding = true;
_flowDirection = flowDirection;
}
/// <summary>
/// Character length
/// </summary>
public sealed override int Length
{
get { return _length; }
}
/// <summary>
/// A set of properties shared by every characters in the run
/// It is null for a TextModifier run.
/// </summary>
public sealed override TextRunProperties Properties
{
get { return null; }
}
/// <summary>
/// Modifies the properties of a text run.
/// </summary>
/// <param name="properties">Properties of a text run or the return value of
/// ModifyProperties for a nested text modifier.</param>
/// <returns>Returns the actual text run properties to be used for formatting,
/// subject to further modification by text modifiers at outer scopes.</returns>
public sealed override TextRunProperties ModifyProperties(TextRunProperties properties)
{
// Get the text decorations applied to the text modifier run. If there are
// none, we don't change anything.
if (properties == null || _modifierDecorations == null || _modifierDecorations.Count == 0)
return properties;
// Let brush be the foreground brush for the text modifier run. Any text
// decorations defined at the text modifier scope that have a null Pen
// should be drawn using this brush, which means we may need to copy some
// TextDecoration objects and set the Pen property on the copies. We can
// elide this if the same brush is used at both scopes. We shouldn't miss
// too many optimization opportunities by using the (lower cost) reference
// comparison here because in most cases where the brushes are equal it's
// because it's an inherited property.
Brush brush = _modifierBrush;
if (object.ReferenceEquals(brush, properties.ForegroundBrush))
{
// No need to set the pen property.
brush = null;
}
// We're going to create a merged set of text decorations.
TextDecorationCollection mergedDecorations;
// Get the text decorations of the affected run, if any.
TextDecorationCollection runDecorations = properties.TextDecorations;
if (runDecorations == null || runDecorations.Count == 0)
{
// Only the text modifier run defines text decorations so
// we don't need to merge anything.
if (brush == null)
{
// Use the text decorations of the modifier run.
mergedDecorations = _modifierDecorations;
}
else
{
// The foreground brushes differ so copy the text decorations to a
// new collection and make sure each has a non-null pen.
mergedDecorations = CopyTextDecorations(_modifierDecorations, brush);
}
}
else
{
// Add the modifier decorations first because we want text decorations
// defined at the inner scope (e.g., by the run) to be drawn on top.
mergedDecorations = CopyTextDecorations(_modifierDecorations, brush);
// Add the text decorations defined at the inner scope; we never need
// to set the pen for these because they should be drawn using the
// foreground brush.
foreach (TextDecoration td in runDecorations)
{
mergedDecorations.Add(td);
}
}
return new MergedTextRunProperties(properties, mergedDecorations);
}
public override bool HasDirectionalEmbedding
{
get { return _hasDirectionalEmbedding; }
}
public override FlowDirection FlowDirection
{
get { return _flowDirection; }
}
private TextDecorationCollection CopyTextDecorations(TextDecorationCollection textDecorations, Brush brush)
{
TextDecorationCollection result = new TextDecorationCollection();
Pen pen = null;
foreach (TextDecoration td in textDecorations)
{
if (td.Pen == null && brush != null)
{
if (pen == null)
pen = new Pen(brush, 1);
TextDecoration copy = td.Clone();
copy.Pen = pen;
result.Add(copy);
}
else
{
result.Add(td);
}
}
return result;
}
private class MergedTextRunProperties : TextRunProperties
{
TextRunProperties _runProperties;
TextDecorationCollection _textDecorations;
internal MergedTextRunProperties(
TextRunProperties runProperties,
TextDecorationCollection textDecorations)
{
_runProperties = runProperties;
_textDecorations = textDecorations;
PixelsPerDip = _runProperties.PixelsPerDip;
}
public override Typeface Typeface
{
get { return _runProperties.Typeface; }
}
public override double FontRenderingEmSize
{
get { return _runProperties.FontRenderingEmSize; }
}
public override double FontHintingEmSize
{
get { return _runProperties.FontHintingEmSize; }
}
public override TextDecorationCollection TextDecorations
{
get { return _textDecorations; }
}
public override Brush ForegroundBrush
{
get { return _runProperties.ForegroundBrush; }
}
public override Brush BackgroundBrush
{
get { return _runProperties.BackgroundBrush; }
}
public override CultureInfo CultureInfo
{
get { return _runProperties.CultureInfo; }
}
public override TextEffectCollection TextEffects
{
get { return _runProperties.TextEffects; }
}
public override BaselineAlignment BaselineAlignment
{
get { return _runProperties.BaselineAlignment; }
}
public override TextRunTypographyProperties TypographyProperties
{
get { return _runProperties.TypographyProperties; }
}
public override NumberSubstitution NumberSubstitution
{
get { return _runProperties.NumberSubstitution; }
}
}
}
}
|