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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: TextLine wrapper used by TextBoxView.
//
using System.Globalization;
using System.Windows.Controls.Primitives;
using System.Windows.Documents;
using System.Windows.Media;
using System.Windows.Media.TextFormatting;
using MS.Internal;
using MS.Internal.Text;
namespace System.Windows.Controls
{
/// <summary>
/// TextLine wrapper used by TextBoxView.
/// </summary>
internal class TextBoxLine : TextSource, IDisposable
{
//-------------------------------------------------------------------
//
// Constructors
//
//-------------------------------------------------------------------
#region Constructors
/// <summary>
/// Constructor.
/// </summary>
/// <param name="owner">Owner of the line.</param>
internal TextBoxLine(TextBoxView owner)
{
_owner = owner;
PixelsPerDip = _owner.GetDpi().PixelsPerDip;
}
#endregion Constructors
// ------------------------------------------------------------------
//
// Public Methods
//
// ------------------------------------------------------------------
#region Public Methods
/// <summary>
/// Free all resources associated with the line. Prepare it for reuse.
/// </summary>
public void Dispose()
{
// Dispose text line
if (_line != null)
{
_line.Dispose();
_line = null;
}
GC.SuppressFinalize(this);
}
/// <summary>
/// Get a text run at specified text source position.
/// </summary>
public override TextRun GetTextRun(int dcp)
{
TextRun run = null;
StaticTextPointer position = _owner.Host.TextContainer.CreateStaticPointerAtOffset(dcp);
switch (position.GetPointerContext(LogicalDirection.Forward))
{
case TextPointerContext.Text:
run = HandleText(position);
break;
case TextPointerContext.None:
run = new TextEndOfParagraph(_syntheticCharacterLength);
break;
case TextPointerContext.ElementStart:
case TextPointerContext.ElementEnd:
case TextPointerContext.EmbeddedElement:
default:
Invariant.Assert(false, "Unsupported position type.");
break;
}
Invariant.Assert(run != null, "TextRun has not been created.");
Invariant.Assert(run.Length > 0, "TextRun has to have positive length.");
if (run.Properties != null)
{
run.Properties.PixelsPerDip = this.PixelsPerDip;
}
return run;
}
/// <summary>
/// Get text immediately before specified text source position.
/// </summary>
public override TextSpan<CultureSpecificCharacterBufferRange> GetPrecedingText(int dcp)
{
CharacterBufferRange precedingText = CharacterBufferRange.Empty;
CultureInfo culture = null;
if (dcp > 0)
{
// Create TextPointer at dcp
ITextPointer position = _owner.Host.TextContainer.CreatePointerAtOffset(dcp, LogicalDirection.Backward);
// Return text in run. If it is at start of TextContainer this will return an empty string.
// Typically the caller requires just the preceding character. Worst case is the entire
// preceding sentence, which we approximate with a 128 char limit.
int runLength = Math.Min(128, position.GetTextRunLength(LogicalDirection.Backward));
char[] text = new char[runLength];
position.GetTextInRun(LogicalDirection.Backward, text, 0, runLength);
precedingText = new CharacterBufferRange(text, 0, runLength);
culture = DynamicPropertyReader.GetCultureInfo((Control)_owner.Host);
}
return new TextSpan<CultureSpecificCharacterBufferRange>(
precedingText.Length, new CultureSpecificCharacterBufferRange(culture, precedingText));
}
/// <summary>
/// TextFormatter to map a text source character index to a text effect character index
/// </summary>
/// <param name="textSourceCharacterIndex"> text source character index </param>
/// <returns> the text effect index corresponding to the text effect character index </returns>
public override int GetTextEffectCharacterIndexFromTextSourceCharacterIndex(int textSourceCharacterIndex)
{
return textSourceCharacterIndex;
}
#endregion Public Methods
//-------------------------------------------------------------------
//
// Internal Methods
//
//-------------------------------------------------------------------
#region Internal Methods
/// <summary>
/// Create and format text line.
/// </summary>
/// <param name="dcp">First character position for the line.</param>
/// <param name="formatWidth">Width to pass to LS formatter.</param>
/// <param name="paragraphWidth">Line wrapping width.</param>
/// <param name="lineProperties">Line's properties.</param>
/// <param name="textRunCache">Run cache.</param>
/// <param name="formatter">Text formatter.</param>
/// <remarks>
/// formatWidth/paragraphWidth is an attempt to work around bug 114719.
/// Unfortunately, Line Services cannot guarantee that once a line
/// has been measured, measuring the same content with the actual line
/// width will produce the same line.
///
/// For example, suppose we format dcp 0 with paragraphWidth = 100.
/// Suppose this results in a line from dcp 0 - 10, with width = 95.
///
/// We would expect that a call to FormatLine with dcp = 0,
/// paragraphWidth = 95 would result in the same 10 char line.
/// But in practice it might return a 9 char line.
///
/// The workaround is to pass in an explicit formatting width across
/// multiple calls, even if the paragraphWidth changes.
/// </remarks>
internal void Format(int dcp, double formatWidth, double paragraphWidth, LineProperties lineProperties, TextRunCache textRunCache, TextFormatter formatter)
{
_lineProperties = lineProperties;
_dcp = dcp;
_paragraphWidth = paragraphWidth;
// We must ignore TextAlignment here since formatWidth does not
// necessarilly equal paragraphWidth. We'll adjust on later calls.
lineProperties.IgnoreTextAlignment = (lineProperties.TextAlignment != TextAlignment.Justify);
try
{
_line = formatter.FormatLine(this, dcp, formatWidth, lineProperties, null, textRunCache);
}
finally
{
lineProperties.IgnoreTextAlignment = false;
}
}
/// <summary>
/// Create and return visual node for the line.
/// </summary>
internal TextBoxLineDrawingVisual CreateVisual(Geometry selectionGeometry)
{
TextBoxLineDrawingVisual visual = new TextBoxLineDrawingVisual();
// Calculate shift in line offset to render trailing spaces or avoid clipping text.
double delta = CalculateXOffsetShift();
DrawingContext ctx = visual.RenderOpen();
if (selectionGeometry != null)
{
var uiScope = _owner?.Host?.TextContainer?.TextSelection?.TextEditor?.UiScope;
if (uiScope != null)
{
Brush selectionBrush = uiScope.GetValue(TextBoxBase.SelectionBrushProperty) as Brush;
if (selectionBrush != null)
{
double selectionBrushOpacity = (double)uiScope.GetValue(TextBoxBase.SelectionOpacityProperty);
ctx.PushOpacity(selectionBrushOpacity);
// We use a Pen created from the brush used for the selection with a default thickness.
// This fixes issues where the geometries for the independent selection do not overlap
// and gaps can be seen to the background of the control between selection geometries.
ctx.DrawGeometry(selectionBrush, new Pen() { Brush = selectionBrush }, selectionGeometry);
ctx.Pop();
}
}
}
_line.Draw(ctx, new Point(delta, 0), ((_lineProperties.FlowDirection == FlowDirection.RightToLeft) ? InvertAxes.Horizontal : InvertAxes.None));
ctx.Close();
return visual;
}
/// <summary>
/// Retrieve bounds of an object/character at specified text position.
/// </summary>
/// <param name="characterIndex">position of an object/character</param>
/// <param name="flowDirection">flow direction of object/character</param>
/// <returns>Bounds of an object/character</returns>
internal Rect GetBoundsFromTextPosition(int characterIndex, out FlowDirection flowDirection)
{
return GetBoundsFromPosition(characterIndex, 1, out flowDirection);
}
/// <summary>
/// Returns a collection of rectangles (Rect) that form the bounds of the region
/// specified between the start and end points.
/// </summary>
/// <param name="cp">Starting point of the region</param>
/// <param name="cch">Length in characters of the region</param>
/// <param name="xOffset">Offset of line in x direction, to be added to line bounds</param>
/// <param name="yOffset">Offset of line in y direction, to be added to line bounds</param>
/// <remarks>
/// This function calls GetTextBounds for the line, and then checks if there are
/// text run bounds. If they exist, it uses those as the bounding rectangles. If not,
/// it returns the rectangle for the first (and only) element of the text bounds.
/// </remarks>
internal List<Rect> GetRangeBounds(int cp, int cch, double xOffset, double yOffset)
{
List<Rect> rectangles = new List<Rect>();
// Adjust x offset for trailing spaces
double delta = CalculateXOffsetShift();
double adjustedXOffset = xOffset + delta;
IList<TextBounds> textBounds = _line.GetTextBounds(cp, cch);
Invariant.Assert(textBounds.Count > 0);
for (int boundIndex = 0; boundIndex < textBounds.Count; boundIndex++)
{
Rect rect = textBounds[boundIndex].Rectangle;
rect.X += adjustedXOffset;
rect.Y += yOffset;
rectangles.Add(rect);
}
return rectangles;
}
/// <summary>
/// Retrieve text position index from the distance.
/// </summary>
/// <param name="distance">distance relative to the beginning of the line</param>
/// <returns>Text position index</returns>
internal CharacterHit GetTextPositionFromDistance(double distance)
{
// Adjust distance to account for a line shift due to rendering of trailing spaces
double delta = CalculateXOffsetShift();
return _line.GetCharacterHitFromDistance(distance - delta);
}
/// <summary>
/// Retrieve text position for next caret position.
/// </summary>
/// <param name="index">CharacterHit for current position</param>
/// <returns>Text position index</returns>
internal CharacterHit GetNextCaretCharacterHit(CharacterHit index)
{
return _line.GetNextCaretCharacterHit(index);
}
/// <summary>
/// Retrieve text position for previous caret position.
/// </summary>
/// <param name="index">CharacterHit for current position</param>
/// <returns>Text position index</returns>
internal CharacterHit GetPreviousCaretCharacterHit(CharacterHit index)
{
return _line.GetPreviousCaretCharacterHit(index);
}
/// <summary>
/// Retrieve text position for backspace caret position.
/// </summary>
/// <param name="index">CharacterHit for current position</param>
/// <returns>Text position index</returns>
internal CharacterHit GetBackspaceCaretCharacterHit(CharacterHit index)
{
return _line.GetBackspaceCaretCharacterHit(index);
}
/// <summary>
/// Returns true of char hit is at caret unit boundary.
/// </summary>
/// <param name="charHit">
/// CharacterHit to be tested.
/// </param>
internal bool IsAtCaretCharacterHit(CharacterHit charHit)
{
return _line.IsAtCaretCharacterHit(charHit, _dcp);
}
#endregion Internal Methods
//-------------------------------------------------------------------
//
// Internal Properties
//
//-------------------------------------------------------------------
#region Internal Properties
/// <summary>
/// Calculated width of the line.
/// </summary>
internal double Width
{
get
{
if (IsWidthAdjusted)
{
// Trailing spaces add to width
return _line.WidthIncludingTrailingWhitespace;
}
else
{
return _line.Width;
}
}
}
/// <summary>
/// Height of the line; line advance distance.
/// </summary>
internal double Height { get { return _line.Height; } }
/// <summary>
/// Is this the last line of the paragraph?
/// </summary>
internal bool EndOfParagraph
{
get
{
// If there are no Newline characters, it is not the end of paragraph.
if (_line.NewlineLength == 0) { return false; }
// Since there are Newline characters in the line, do more expensive and
// accurate check.
IList<TextSpan<TextRun>> runs = _line.GetTextRunSpans();
return (((TextSpan<TextRun>)runs[runs.Count - 1]).Value is TextEndOfParagraph);
}
}
/// <summary>
/// Length of the line excluding any synthetic characters.
/// </summary>
internal int Length
{
get { return _line.Length - (EndOfParagraph ? 1 : 0); }
}
/// <summary>
/// Length of the line excluding any synthetic characters and line breaks.
/// </summary>
internal int ContentLength { get { return _line.Length - _line.NewlineLength; } }
/// <summary>
/// True if line ends in hard line break.
/// </summary>
internal bool HasLineBreak
{
get
{
return (_line.NewlineLength > 0);
}
}
#endregion Internal Properties
//-------------------------------------------------------------------
//
// Private Methods
//
//-------------------------------------------------------------------
#region Private Methods
/// <summary>
/// Fetch the next run at text position.
/// </summary>
private TextRun HandleText(StaticTextPointer position)
{
// Calculate the end of the run by finding either:
// a) the next intersection of highlight ranges, or
// b) the natural end of this textrun
StaticTextPointer endOfRunPosition = _owner.Host.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);
}
var highlights = position.TextContainer.Highlights;
// Factor in any speller error squiggles on the run.
TextDecorationCollection highlightDecorations = highlights.GetHighlightValue(position, LogicalDirection.Forward, typeof(SpellerHighlightLayer)) as TextDecorationCollection;
TextRunProperties properties = _lineProperties.DefaultTextRunProperties;
if (highlightDecorations != null)
{
if (_spellerErrorProperties == null)
{
_spellerErrorProperties = new TextProperties((TextProperties)properties, highlightDecorations);
}
properties = _spellerErrorProperties;
}
var textEditor = position.TextContainer.TextSelection?.TextEditor;
// Apply selection highlighting if needed
if ((textEditor?.TextView?.RendersOwnSelection == true)
&& highlights.GetHighlightValue(position, LogicalDirection.Forward, typeof(TextSelection)) != DependencyProperty.UnsetValue)
{
// We need to create a new TextProperties instance here since we are going to change the Foreground and Background.
var selectionProps = new TextProperties((TextProperties)properties, highlightDecorations);
// The UiScope that owns this line should be the source for text/highlight properties
var uiScope = textEditor?.UiScope;
if (uiScope != null)
{
// Background should not be drawn since the selection is drawn below us
selectionProps.SetBackgroundBrush(null);
Brush selectionTextBrush = uiScope.GetValue(TextBoxBase.SelectionTextBrushProperty) as Brush;
if (selectionTextBrush != null)
{
selectionProps.SetForegroundBrush(selectionTextBrush);
}
}
properties = selectionProps;
}
// Get character buffer for the text run.
char[] textBuffer = new char[position.GetOffsetToPosition(endOfRunPosition)];
// Copy characters from text run into buffer. Since we are dealing with plain text content,
// we expect to get all the characters from position to endOfRunPosition.
int charactersCopied = position.GetTextInRun(LogicalDirection.Forward, textBuffer, 0, textBuffer.Length);
Invariant.Assert(charactersCopied == textBuffer.Length);
// Create text run, using characters copied as length
return new TextCharacters(textBuffer, 0, charactersCopied, properties);
}
/// <summary>
/// Retrieve bounds of an object/character at specified text index.
/// </summary>
/// <param name="cp">character index of an object/character</param>
/// <param name="cch">number of positions occupied by object/character</param>
/// <param name="flowDirection">flow direction of object/character</param>
/// <returns>Bounds of an object/character</returns>
private Rect GetBoundsFromPosition(int cp, int cch, out FlowDirection flowDirection)
{
Rect rect;
// Adjust x offset for trailing spaces
double delta = CalculateXOffsetShift();
IList<TextBounds> textBounds = _line.GetTextBounds(cp, cch);
Invariant.Assert(textBounds != null && textBounds.Count == 1, "Expecting exactly one TextBounds for a single text position.");
IList<TextRunBounds> runBounds = textBounds[0].TextRunBounds;
if (runBounds != null)
{
Invariant.Assert(runBounds.Count == 1, "Expecting exactly one TextRunBounds for a single text position.");
rect = runBounds[0].Rectangle;
}
else
{
rect = textBounds[0].Rectangle;
}
rect.X += delta;
flowDirection = textBounds[0].FlowDirection;
return rect;
}
/// <summary>
/// Returns amount of shift for X-offset to render trailing spaces
/// and TextAlignment offset.
/// </summary>
private double CalculateXOffsetShift()
{
double xOffset = 0;
if (_lineProperties.TextAlignmentInternal == TextAlignment.Right)
{
xOffset = _paragraphWidth - _line.Width;
}
else if (_lineProperties.TextAlignmentInternal == TextAlignment.Center)
{
xOffset = (_paragraphWidth - _line.Width) / 2;
}
if (IsXOffsetAdjusted)
{
if (_lineProperties.TextAlignmentInternal == TextAlignment.Center)
{
// Return trailing spaces length divided by two so line remains centered.
xOffset += (_line.Width - _line.WidthIncludingTrailingWhitespace) / 2;
}
else
{
xOffset += (_line.Width - _line.WidthIncludingTrailingWhitespace);
}
}
return xOffset;
}
#endregion Private Methods
//-------------------------------------------------------------------
//
// Private Properites
//
//-------------------------------------------------------------------
#region Private Properties
/// <summary>
/// True if line's X-offset needs adjustment to render trailing spaces.
/// </summary>
private bool IsXOffsetAdjusted
{
get
{
return ((_lineProperties.TextAlignmentInternal == TextAlignment.Right || _lineProperties.TextAlignmentInternal == TextAlignment.Center) && IsWidthAdjusted);
}
}
/// <summary>
/// True if line's width is adjusted to include trailing spaces. For right and center alignment we need to
/// adjust line offset as well, but for left alignment we need to only make a width asjustment.
/// </summary>
private bool IsWidthAdjusted
{
get
{
// Trailing spaces rendered only around hard breaks
return (HasLineBreak || EndOfParagraph);
}
}
#endregion Private Properties
//-------------------------------------------------------------------
//
// Private Fields
//
//-------------------------------------------------------------------
#region Private Fields
/// <summary>
/// Owner of the line.
/// </summary>
private readonly TextBoxView _owner;
/// <summary>
/// Cached text line.
/// </summary>
private TextLine _line;
/// <summary>
/// Index of the first character in the line.
/// </summary>
private int _dcp;
/// <summary>
/// Properties of the line.
/// </summary>
private LineProperties _lineProperties;
/// <summary>
/// Properties of the line when covered by a spelling error squiggle.
/// </summary>
private TextProperties _spellerErrorProperties;
/// <summary>
/// Width of the enclosing paragraph, used for TextAlignment calculations.
/// </summary>
private double _paragraphWidth;
/// <summary>
/// TextEndOfParagraph character count.
/// </summary>
private const int _syntheticCharacterLength = 1;
#endregion Private Fields
}
}
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