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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.
//
// Description: Text line formatter.
//
using System.Windows;
using System.Windows.Documents;
using System.Windows.Media.TextFormatting;
using MS.Internal.Text;
using MS.Internal.Documents;
using MS.Internal.PtsHost.UnsafeNativeMethods;
#pragma warning disable 1634, 1691 // avoid generating warnings about unknown
// message numbers and unknown pragmas for PRESharp contol
namespace MS.Internal.PtsHost
{
internal abstract class LineBase : UnmanagedHandle
{
internal LineBase(BaseParaClient paraClient) : base(paraClient.PtsContext)
{
_paraClient = paraClient;
}
// ------------------------------------------------------------------
//
// TextSource Implementation
//
// ------------------------------------------------------------------
#region TextSource Implementation
/// <summary>
/// Get a text run at specified text source position.
/// </summary>
/// <param name="dcp">
/// dcp of specified position relative to start of line
/// </param>
internal abstract TextRun GetTextRun(int dcp);
/// <summary>
/// Get text immediately before specified text source position.
/// </summary>
/// <param name="dcp">
/// dcp of specified position relative to start of line
/// </param>
internal abstract TextSpan<CultureSpecificCharacterBufferRange> GetPrecedingText(int dcp);
/// <summary>
/// Get Text effect index from text source character index
/// </summary>
/// <param name="dcp">
/// dcp of specified position relative to start of line
/// </param>
internal abstract int GetTextEffectCharacterIndexFromTextSourceCharacterIndex(int dcp);
#endregion TextSource Implementation
//-------------------------------------------------------------------
//
// Protected Methods
//
//-------------------------------------------------------------------
#region Protected Methods
/// <summary>
/// Fetch the next run at text position.
/// </summary>
/// <param name="position">
/// Current position in text array
/// </param>
/// <returns></returns>
protected TextRun HandleText(StaticTextPointer position)
{
DependencyObject element;
StaticTextPointer endOfRunPosition;
Invariant.Assert(position.GetPointerContext(LogicalDirection.Forward) == TextPointerContext.Text, "TextPointer does not point to characters.");
if (position.Parent != null)
{
element = position.Parent;
}
else
{
element = _paraClient.Paragraph.Element;
}
// Extract the aggregated properties into something that the textrun can use.
// For properties that can be applied to Highlight services, need to use 'textHighlights'.
// Right now only background is properly retrieved.
TextProperties textProps = new TextProperties(element, position, false /* inline objects */, true /* get background */,
_paraClient.Paragraph.StructuralCache.TextFormatterHost.PixelsPerDip);
// Calculate the end of the run by finding either:
// a) the next intersection of highlight ranges, or
// b) the natural end of this textrun
endOfRunPosition = position.TextContainer.Highlights.GetNextPropertyChangePosition(position, LogicalDirection.Forward);
// Clamp the text run at an arbitrary limit, so we don't make
// an unbounded allocation.
if (position.GetOffsetToPosition(endOfRunPosition) > 4096)
{
endOfRunPosition = position.CreatePointer(4096);
}
// Get character buffer for the text run.
char[] textBuffer = new char[position.GetOffsetToPosition(endOfRunPosition)];
// Copy characters from text run into buffer. Note the actual number of characters copied,
// which may be different than the buffer's length. Buffer length only specifies the maximum
// number of characters
int charactersCopied = position.GetTextInRun(LogicalDirection.Forward, textBuffer, 0, textBuffer.Length);
// Create text run using the actual number of characters copied
return new TextCharacters(textBuffer, 0, charactersCopied, textProps);
}
/// <summary>
/// Return next TextRun at element edge start position
/// </summary>
/// <param name="position">
/// Current position in text array
/// </param>
protected TextRun HandleElementStartEdge(StaticTextPointer position)
{
Invariant.Assert(position.GetPointerContext(LogicalDirection.Forward) == TextPointerContext.ElementStart, "TextPointer does not point to element start edge.");
// In the future, handle visibility collapsed.
TextRun run = null;
TextElement element = (TextElement)position.GetAdjacentElement(LogicalDirection.Forward);
Debug.Assert(element != null, "Cannot use ITextContainer that does not provide TextElement instances.");
Invariant.Assert(!(element is Block), "We do not expect any Blocks inside Paragraphs");
// Treat figure and floaters as special hidden runs.
if (element is Figure || element is Floater)
{
// Get the length of the element
int cch = TextContainerHelper.GetElementLength(_paraClient.Paragraph.StructuralCache.TextContainer, element);
// Create special hidden run.
run = new FloatingRun(cch, element is Figure);
if (element is Figure)
{
_hasFigures = true;
}
else
{
_hasFloaters = true;
}
}
else if (element is LineBreak)
{
int cch = TextContainerHelper.GetElementLength(_paraClient.Paragraph.StructuralCache.TextContainer, element);
run = new LineBreakRun(cch, PTS.FSFLRES.fsflrSoftBreak);
}
else if (element.IsEmpty)
{
// Empty TextElement should affect line metrics.
// TextFormatter does not support this feature right now, so as workaround
// TextRun with ZERO WIDTH SPACE is used.
TextProperties textProps = new TextProperties(element, position, false /* inline objects */, true /* get background */,
_paraClient.Paragraph.StructuralCache.TextFormatterHost.PixelsPerDip);
char[] textBuffer = new char[_elementEdgeCharacterLength * 2];
// Assert that _elementEdgeCharacterLength is 1 before we use hard-coded indices
Invariant.Assert(_elementEdgeCharacterLength == 1, "Expected value of _elementEdgeCharacterLength is 1");
textBuffer[0] = (char)0x200B;
textBuffer[1] = (char)0x200B;
run = new TextCharacters(textBuffer, 0, textBuffer.Length, textProps);
}
else
{
Inline inline = (Inline) element;
DependencyObject parent = inline.Parent;
FlowDirection inlineFlowDirection = inline.FlowDirection;
FlowDirection parentFlowDirection = inlineFlowDirection;
TextDecorationCollection inlineTextDecorations = DynamicPropertyReader.GetTextDecorations(inline);
if(parent != null)
{
parentFlowDirection = (FlowDirection)parent.GetValue(FrameworkElement.FlowDirectionProperty);
}
if (inlineFlowDirection != parentFlowDirection)
{
// Inline's flow direction is different from its parent. Need to create new TextSpanModifier with flow direction
if (inlineTextDecorations == null || inlineTextDecorations.Count == 0)
{
run = new TextSpanModifier(
_elementEdgeCharacterLength,
null,
null,
inlineFlowDirection
);
}
else
{
run = new TextSpanModifier(
_elementEdgeCharacterLength,
inlineTextDecorations,
inline.Foreground,
inlineFlowDirection
);
}
}
else
{
if (inlineTextDecorations == null || inlineTextDecorations.Count == 0)
{
run = new TextHidden(_elementEdgeCharacterLength);
}
else
{
run = new TextSpanModifier(
_elementEdgeCharacterLength,
inlineTextDecorations,
inline.Foreground
);
}
}
}
return run;
}
/// <summary>
/// Fetch the next run at element end edge position.
/// ElementEndEdge; we can have 2 possibilities:
/// (1) Close edge of element associated with the text paragraph,
/// create synthetic LineBreak run to end the current line.
/// (2) End of inline element, hide CloseEdge character and continue
/// </summary>
/// <param name="position"></param>
/// Position in current text array
protected TextRun HandleElementEndEdge(StaticTextPointer position)
{
Invariant.Assert(position.GetPointerContext(LogicalDirection.Forward) == TextPointerContext.ElementEnd, "TextPointer does not point to element end edge.");
TextRun run;
if (position.Parent == _paraClient.Paragraph.Element)
{
// (1) Close edge of element associated with the text paragraph,
// create synthetic LineBreak run to end the current line.
run = new ParagraphBreakRun(_syntheticCharacterLength, PTS.FSFLRES.fsflrEndOfParagraph);
}
else
{
TextElement element = (TextElement)position.GetAdjacentElement(LogicalDirection.Forward);
Debug.Assert(element != null, "Element should be here.");
Inline inline = (Inline) element;
DependencyObject parent = inline.Parent;
FlowDirection parentFlowDirection = inline.FlowDirection;
if(parent != null)
{
parentFlowDirection = (FlowDirection)parent.GetValue(FrameworkElement.FlowDirectionProperty);
}
if (inline.FlowDirection != parentFlowDirection)
{
run = new TextEndOfSegment(_elementEdgeCharacterLength);
}
else
{
TextDecorationCollection textDecorations = DynamicPropertyReader.GetTextDecorations(inline);
if (textDecorations == null || textDecorations.Count == 0)
{
// (2) End of inline element, hide CloseEdge character and continue
run = new TextHidden(_elementEdgeCharacterLength);
}
else
{
run = new TextEndOfSegment(_elementEdgeCharacterLength);
}
}
}
return run;
}
/// <summary>
/// Fetch the next run at embedded object position.
/// </summary>
/// <param name="dcp">
/// Character offset of this run.
/// </param>
/// <param name="position">
/// Current position in the text array.
/// </param>
protected TextRun HandleEmbeddedObject(int dcp, StaticTextPointer position)
{
Invariant.Assert(position.GetPointerContext(LogicalDirection.Forward) == TextPointerContext.EmbeddedElement, "TextPointer does not point to embedded object.");
TextRun run = null;
DependencyObject embeddedObject = position.GetAdjacentElement(LogicalDirection.Forward) as DependencyObject;
if (embeddedObject is UIElement)
{
// Extract the aggregated properties into something that the textrun can use.
TextRunProperties textProps = new TextProperties(embeddedObject, position, true /* inline objects */, true /* get background */,
_paraClient.Paragraph.StructuralCache.TextFormatterHost.PixelsPerDip);
// Create inline object run.
run = new InlineObjectRun(TextContainerHelper.EmbeddedObjectLength, (UIElement)embeddedObject, textProps, _paraClient.Paragraph as TextParagraph);
}
else
{
// If the embedded object is of an unknown type, treat it as hidden content.
run = new TextHidden(TextContainerHelper.EmbeddedObjectLength);
}
return run;
}
#endregion Protected Methods
#region Internal Methods
/// <summary>
/// Synthetic character length.
/// </summary>
internal static int SyntheticCharacterLength
{
get
{
return _syntheticCharacterLength;
}
}
/// <summary>
/// Returns true if any figure runs have been handled by this text source - Only valid after line is formatted.
/// </summary>
internal bool HasFigures
{
get { return _hasFigures; }
}
/// <summary>
/// Returns true if any floater runs have been handled by this text source - Only valid after line is formatted.
/// </summary>
internal bool HasFloaters
{
get { return _hasFloaters; }
}
#endregion Internal Methods
#region Protected Fields
/// <summary>
/// Owner of the line
/// </summary>
protected readonly BaseParaClient _paraClient;
/// <summary>
/// Has any figures?
/// </summary>
protected bool _hasFigures;
/// <summary>
/// Has any floaters?
/// </summary>
protected bool _hasFloaters;
protected static int _syntheticCharacterLength = 1;
/// <summary>
/// Element edge character length.
/// Text and TextFlow assume that ElementEdge position has
/// always length = 1.
/// </summary>
protected static int _elementEdgeCharacterLength = 1;
#endregion Protected Fields
}
}
#pragma warning enable 1634, 1691
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