void IndeterminateProgressThreadProc( )
{
try
{
Thread.Sleep(2222);
UITaskHelper.Invoke(this, CancellationToken.None,
() =>
{
ucMatches.ShowIndeterminateProgress(true);
ucMatches.ShowInfo("The engine is busy, please wait…", true);
ucText.SetMatches(RegexMatches.Empty, cbShowCaptures.IsChecked == true, GetEolOption( ));
});
}
catch (ThreadInterruptedException)
{
// ignore
}
catch (ThreadAbortException)
{
// ignore
}
catch (Exception exc)
{
_ = exc;
if (Debugger.IsAttached)
{
Debugger.Break( );
}
// ignore
}
}
void RecolouringThreadProc(ICancellable cnc)
{
RegexMatches matches;
string eol;
bool show_captures;
lock (this)
{
matches = LastMatches;
eol = LastEol;
show_captures = LastShowCaptures;
}
TextData td = null;
Rect clip_rect = Rect.Empty;
int top_index = 0;
int bottom_index = 0;
UITaskHelper.Invoke(rtb, () =>
{
td = null;
var start_doc = rtb.Document.ContentStart;
var end_doc = rtb.Document.ContentStart;
if (!start_doc.HasValidLayout || !end_doc.HasValidLayout)
{
return;
}
var td0 = rtb.GetTextData(eol);
if (cnc.IsCancellationRequested)
{
return;
}
td = td0;
clip_rect = new Rect(new Size(rtb.ViewportWidth, rtb.ViewportHeight));
TextPointer top_pointer = rtb.GetPositionFromPoint(new Point(0, 0), snapToText: true).GetLineStartPosition(-1, out int _);
if (cnc.IsCancellationRequested)
{
return;
}
top_index = td.TextPointers.GetIndex(top_pointer, LogicalDirection.Backward);
if (cnc.IsCancellationRequested)
{
return;
}
if (top_index < 0)
{
top_index = 0;
}
TextPointer bottom_pointer = rtb.GetPositionFromPoint(new Point(0, rtb.ViewportHeight), snapToText: true).GetLineStartPosition(+1, out int lines_skipped);
if (cnc.IsCancellationRequested)
{
return;
}
if (bottom_pointer == null || lines_skipped == 0)
{
bottom_index = td.Text.Length;
}
else
{
bottom_index = td.TextPointers.GetIndex(bottom_pointer, LogicalDirection.Forward);
if (cnc.IsCancellationRequested)
{
return;
}
}
if (bottom_index > td.Text.Length)
{
bottom_index = td.Text.Length;
}
if (bottom_index < top_index)
{
bottom_index = top_index; // (including 'if bottom_index == 0')
}
});
if (cnc.IsCancellationRequested)
{
return;
}
if (td == null)
{
return;
}
if (td.Text.Length == 0)
{
return;
}
Debug.Assert(top_index >= 0);
Debug.Assert(bottom_index >= top_index);
Debug.Assert(bottom_index <= td.Text.Length);
// (NOTE. Overlaps are possible in this example: (?=(..))
var segments_and_styles = new List <(Segment segment, StyleInfo styleInfo)>( );
var segments_to_uncolour = new List <Segment>( );
segments_to_uncolour.Add(new Segment(top_index, bottom_index - top_index + 1));
if (matches != null && matches.Count > 0)
{
int i = -1;
foreach (var match in matches.Matches)
{
++i;
if (cnc.IsCancellationRequested)
{
break;
}
Debug.Assert(match.Success);
// TODO: consider these conditions for bi-directional text
if (match.TextIndex + match.TextLength < top_index)
{
continue;
}
if (match.TextIndex > bottom_index)
{
continue; // (do not break; the order of indices is unspecified)
}
var highlight_index = unchecked (i % HighlightStyleInfos.Length);
Segment.Except(segments_to_uncolour, match.TextIndex, match.TextLength);
segments_and_styles.Add((new Segment(match.TextIndex, match.TextLength), HighlightStyleInfos[highlight_index]));
}
}
if (cnc.IsCancellationRequested)
{
return;
}
List <(Segment segment, StyleInfo styleInfo)> segments_to_uncolour_with_style =
segments_to_uncolour
.Select(s => (s, NormalStyleInfo))
.ToList( );
if (cnc.IsCancellationRequested)
{
return;
}
int center_index = (top_index + bottom_index) / 2;
var all_segments_and_styles =
segments_and_styles.Concat(segments_to_uncolour_with_style)
.OrderBy(s => Math.Abs(center_index - (s.segment.Index + s.segment.Length / 2)))
.ToList( );
if (cnc.IsCancellationRequested)
{
return;
}
RtbUtilities.ApplyStyle(cnc, ChangeEventHelper, pbProgress, td, all_segments_and_styles);
if (cnc.IsCancellationRequested)
{
return;
}
UITaskHelper.BeginInvoke(pbProgress, () =>
{
pbProgress.Visibility = Visibility.Hidden;
});
}
bool CollectEof(ICancellable cnc, TextData td, Rect clip_rect, int top_index)
{
if (cnc.IsCancellationRequested)
{
return(false);
}
var rtb = Rtb;
double max_x = double.NaN;
Rect end_rect = Rect.Empty;
UITaskHelper.Invoke(rtb,
() =>
{
var end = rtb.Document.ContentEnd;
end_rect = end.GetCharacterRect(LogicalDirection.Forward); // (no width)
if (end_rect.Bottom < clip_rect.Top || end_rect.Top > clip_rect.Bottom)
{
return;
}
max_x = end_rect.Left;
// if no RTL, then return a quick answer
var begin_line = end.GetLineStartPosition(0);
if (begin_line != null)
{
var r = new TextRange(begin_line, end);
var text = r.Text;
bool has_RTL = false;
for (int k = 0; k < text.Length; ++k)
{
if (cnc.IsCancellationRequested)
{
return;
}
if (UnicodeUtilities.IsRTL(text[k]))
{
has_RTL = true;
break;
}
}
if (!has_RTL)
{
return;
}
}
// we have RTL segments that need additional navigation to find the rightmost X
for (var tp = end; ;)
{
if (cnc.IsCancellationRequested)
{
return;
}
tp = tp.GetNextInsertionPosition(LogicalDirection.Backward);
if (tp == null)
{
break;
}
// WORKAROUND for lines like "0ראל", when "0" is matched and highlighted
tp = tp.GetInsertionPosition(LogicalDirection.Forward);
var rect = tp.GetCharacterRect(LogicalDirection.Forward);
if (rect.Bottom < end_rect.Bottom)
{
break;
}
if (max_x < rect.Left)
{
max_x = rect.Left;
}
}
});
if (cnc.IsCancellationRequested)
{
return(false);
}
lock (this)
{
if (double.IsNaN(max_x))
{
PositionEof = Rect.Empty;
}
else
{
PositionEof = new Rect(new Point(max_x, end_rect.Top), end_rect.Size);
PositionEof.Offset(rtb.HorizontalOffset, rtb.VerticalOffset);
}
}
DelayedInvalidateVisual( );
return(true);
}
bool CollectEols(ICancellable cnc, TextData td, Rect clip_rect, int top_index)
{
if (cnc.IsCancellationRequested)
{
return(false);
}
var rtb = Rtb;
List <Rect> positions_eols = new List <Rect>( );
// lines with no right-to-left segments
var matches = EolRegex.Matches(td.Text);
for (int i = 0; i < matches.Count; ++i)
{
if (cnc.IsCancellationRequested)
{
return(false);
}
int index = matches[i].Index;
if (index < top_index)
{
continue;
}
int previous_index = i == 0 ? 0 : matches[i - 1].Index;
bool has_RTL = false;
for (int k = previous_index; k < index; ++k)
{
if (cnc.IsCancellationRequested)
{
return(false);
}
if (UnicodeUtilities.IsRTL(td.Text[k]))
{
has_RTL = true;
break;
}
}
if (has_RTL)
{
// RTL needs more navigation to find the rightmost X
Rect left_rect = Rect.Empty;
double max_x = double.NaN;
bool should_continue = false;
bool should_break = false;
UITaskHelper.Invoke(rtb,
() =>
{
TextPointer left = td.TextPointers.GetTextPointer(index);
left_rect = left.GetCharacterRect(LogicalDirection.Forward);
if (left_rect.Bottom < clip_rect.Top)
{
should_continue = true; return;
}
if (left_rect.Top > clip_rect.Bottom)
{
should_break = true; return;
}
max_x = left_rect.Left;
for (var tp = left.GetInsertionPosition(LogicalDirection.Backward); ;)
{
if (cnc.IsCancellationRequested)
{
return;
}
tp = tp.GetNextInsertionPosition(LogicalDirection.Backward);
if (tp == null)
{
break;
}
// WORKAROUND for lines like "0ראל", when "0" is matched and highlighted
tp = tp.GetInsertionPosition(LogicalDirection.Forward);
var rect_b = tp.GetCharacterRect(LogicalDirection.Backward);
var rect_f = tp.GetCharacterRect(LogicalDirection.Forward);
if (cnc.IsCancellationRequested)
{
return;
}
if (rect_b.Bottom < left_rect.Top && rect_f.Bottom < left_rect.Top)
{
break;
}
if (rect_b.Bottom > left_rect.Top)
{
if (max_x < rect_b.Left)
{
max_x = rect_b.Left;
}
}
if (rect_f.Bottom > left_rect.Top)
{
if (max_x < rect_f.Left)
{
max_x = rect_f.Left;
}
}
}
});
if (cnc.IsCancellationRequested)
{
return(false);
}
if (should_continue)
{
continue;
}
if (should_break)
{
break;
}
Rect eol_rect = new Rect(new Point(max_x, left_rect.Top), left_rect.Size);
eol_rect.Offset(rtb.HorizontalOffset, rtb.VerticalOffset);
positions_eols.Add(eol_rect);
}
else
{
// no RTL; quick answer
Rect eol_rect = Rect.Empty;
UITaskHelper.Invoke(rtb,
() =>
{
TextPointer left = td.TextPointers.GetTextPointer(index);
eol_rect = left.GetCharacterRect(LogicalDirection.Forward);
});
if (eol_rect.Bottom < clip_rect.Top)
{
continue;
}
if (eol_rect.Top > clip_rect.Bottom)
{
break;
}
eol_rect.Offset(rtb.HorizontalOffset, rtb.VerticalOffset);
positions_eols.Add(eol_rect);
}
}
if (cnc.IsCancellationRequested)
{
return(false);
}
lock (this)
{
PositionsEols = positions_eols;
}
DelayedInvalidateVisual( );
return(true);
}
void ThreadProc(ICancellable cnc)
{
if (!mShowWhitespaces)
{
return;
}
var rtb = Rtb;
TextData td = null;
Rect clip_rect = Rect.Empty;
int top_index = 0;
UITaskHelper.Invoke(rtb,
() =>
{
td = null;
var start_doc = rtb.Document.ContentStart;
var end_doc = rtb.Document.ContentStart;
if (!start_doc.HasValidLayout || !end_doc.HasValidLayout)
{
return;
}
var td0 = rtb.GetTextData(null);
if (cnc.IsCancellationRequested)
{
return;
}
td = td0;
clip_rect = new Rect(new Size(rtb.ViewportWidth, rtb.ViewportHeight));
TextPointer start_pointer = rtb.GetPositionFromPoint(new Point(0, 0), snapToText: true).GetLineStartPosition(-1, out int unused);
top_index = td.TextPointers.GetIndex(start_pointer, LogicalDirection.Backward);
if (top_index < 0)
{
top_index = 0;
}
});
if (cnc.IsCancellationRequested)
{
return;
}
if (td != null)
{
CollectEols(cnc, td, clip_rect, top_index);
if (cnc.IsCancellationRequested)
{
return;
}
CollectEof(cnc, td, clip_rect, top_index);
if (cnc.IsCancellationRequested)
{
return;
}
CollectSpaces(cnc, td, clip_rect, top_index);
}
}
void UpdateWhitespaceWarningThreadProc(ICancellable cnc)
{
bool has_whitespaces = false;
bool show_whitespaces_option = false;
string eol = null;
BaseTextData td = null;
UITaskHelper.Invoke(this,
() =>
{
show_whitespaces_option = cbShowWhitespaces.IsChecked == true;
eol = GetEolOption( );
td = ucPattern.GetBaseTextData(eol);
if (cnc.IsCancellationRequested)
{
return;
}
});
if (cnc.IsCancellationRequested)
{
return;
}
has_whitespaces = RegexHasWhitespace.IsMatch(td.Text);
if (!has_whitespaces)
{
UITaskHelper.Invoke(this,
() =>
{
td = ucText.GetBaseTextData(eol);
});
has_whitespaces = RegexHasWhitespace.IsMatch(td.Text);
}
bool show1 = false;
bool show2 = false;
if (show_whitespaces_option)
{
if (has_whitespaces)
{
show2 = true;
}
}
else
{
if (has_whitespaces)
{
show1 = true;
}
}
UITaskHelper.Invoke(this,
() =>
{
if (show1 && lblWhitespaceWarning1.Parent == null)
{
lblWarnings.Inlines.Add(lblWhitespaceWarning1);
}
if (!show1 && lblWhitespaceWarning1.Parent != null)
{
lblWarnings.Inlines.Remove(lblWhitespaceWarning1);
}
if (show2 && lblWhitespaceWarning2.Parent == null)
{
lblWarnings.Inlines.Add(lblWhitespaceWarning2);
}
if (!show2 && lblWhitespaceWarning2.Parent != null)
{
lblWarnings.Inlines.Remove(lblWhitespaceWarning2);
}
});
}
void FindMatchesThreadProc(ICancellable cnc)
{
string eol = null;
string pattern = null;
string text = null;
bool first_only = false;
IRegexEngine engine = null;
UITaskHelper.Invoke(this,
() =>
{
eol = GetEolOption( );
pattern = ucPattern.GetBaseTextData(eol).Text;
if (cnc.IsCancellationRequested)
{
return;
}
text = ucText.GetBaseTextData(eol).Text;
if (cnc.IsCancellationRequested)
{
return;
}
first_only = cbShowFirstOnly.IsChecked == true;
engine = CurrentRegexEngine;
});
if (cnc.IsCancellationRequested)
{
return;
}
if (string.IsNullOrEmpty(pattern))
{
UITaskHelper.BeginInvoke(this,
() =>
{
ucText.SetMatches(RegexMatches.Empty, cbShowCaptures.IsChecked == true, GetEolOption( ));
ucMatches.ShowNoPattern( );
lblMatches.Text = "Matches";
pnlShowAll.Visibility = Visibility.Collapsed;
pnlShowFirst.Visibility = Visibility.Collapsed;
});
}
else
{
IMatcher parsed_pattern = null;
RegexMatches matches = null;
bool is_good = false;
try
{
UITaskHelper.BeginInvoke(this, CancellationToken.None, () => ucMatches.ShowMatchingInProgress(true));
parsed_pattern = engine.ParsePattern(pattern);
var indeterminate_progress_thread = new Thread(IndeterminateProgressThreadProc)
{
IsBackground = true
};
try
{
indeterminate_progress_thread.Start( );
matches = parsed_pattern.Matches(text, cnc);
}
finally
{
HideIndeterminateProgress(indeterminate_progress_thread);
}
is_good = true;
}
catch (Exception exc)
{
if (cnc.IsCancellationRequested)
{
return;
}
UITaskHelper.BeginInvoke(this, CancellationToken.None,
() =>
{
ucText.SetMatches(RegexMatches.Empty, cbShowCaptures.IsChecked == true, GetEolOption( ));
ucMatches.ShowError(exc, engine.Capabilities.HasFlag(RegexEngineCapabilityEnum.ScrollErrorsToEnd));
lblMatches.Text = "Error";
pnlShowAll.Visibility = Visibility.Collapsed;
pnlShowFirst.Visibility = Visibility.Collapsed;
});
Debug.Assert(!is_good);
}
finally
{
UITaskHelper.BeginInvoke(this, CancellationToken.None, () => ucMatches.ShowMatchingInProgress(false));
}
if (cnc.IsCancellationRequested)
{
return;
}
if (is_good)
{
int count = matches.Count;
var matches_to_show = first_only ?
new RegexMatches(Math.Min(1, count), matches.Matches.Take(1)) :
matches;
if (cnc.IsCancellationRequested)
{
return;
}
UITaskHelper.BeginInvoke(this,
() =>
{
ucText.SetMatches(matches_to_show, cbShowCaptures.IsChecked == true, GetEolOption( ));
ucMatches.SetMatches(text, matches_to_show, first_only, cbShowSucceededGroupsOnly.IsChecked == true, cbShowCaptures.IsChecked == true);
lblMatches.Text = count == 0 ? "Matches" : count == 1 ? "1 match" : $"{count:#,##0} matches";
pnlShowAll.Visibility = first_only && count > 1 ? Visibility.Visible : Visibility.Collapsed;
pnlShowFirst.Visibility = !first_only && count > 1 ? Visibility.Visible : Visibility.Collapsed;
});
}
}
}
void HighlightingThreadProc(ICancellable cnc)
{
IRegexEngine regex_engine;
string eol;
lock (this)
{
regex_engine = mRegexEngine;
eol = mEol;
}
if (regex_engine == null)
{
return;
}
TextData td = null;
Rect clip_rect = Rect.Empty;
int top_index = 0;
int bottom_index = 0;
bool is_focused = false;
UITaskHelper.Invoke(rtb, () =>
{
td = null;
var start_doc = rtb.Document.ContentStart;
var end_doc = rtb.Document.ContentStart;
if (!start_doc.HasValidLayout || !end_doc.HasValidLayout)
{
return;
}
var td0 = rtb.GetTextData(eol);
if (cnc.IsCancellationRequested)
{
return;
}
td = td0;
clip_rect = new Rect(new Size(rtb.ViewportWidth, rtb.ViewportHeight));
TextPointer top_pointer = rtb.GetPositionFromPoint(new Point(0, 0), snapToText: true).GetLineStartPosition(-1, out int _);
if (cnc.IsCancellationRequested)
{
return;
}
top_index = td.TextPointers.GetIndex(top_pointer, LogicalDirection.Backward);
if (top_index < 0)
{
top_index = 0;
}
TextPointer bottom_pointer = rtb.GetPositionFromPoint(new Point(0, rtb.ViewportHeight), snapToText: true).GetLineStartPosition(+1, out int lines_skipped);
if (cnc.IsCancellationRequested)
{
return;
}
if (bottom_pointer == null || lines_skipped == 0)
{
bottom_index = td.Text.Length;
}
else
{
bottom_index = td.TextPointers.GetIndex(bottom_pointer, LogicalDirection.Forward);
if (cnc.IsCancellationRequested)
{
return;
}
}
if (bottom_index > td.Text.Length)
{
bottom_index = td.Text.Length;
}
if (bottom_index < top_index)
{
bottom_index = top_index; // (including 'if bottom_index == 0')
}
is_focused = rtb.IsFocused;
});
if (cnc.IsCancellationRequested)
{
return;
}
if (td == null)
{
return;
}
if (td.Text.Length == 0)
{
return;
}
Debug.Assert(top_index >= 0);
Debug.Assert(bottom_index >= top_index);
Debug.Assert(bottom_index <= td.Text.Length);
Highlights highlights = null;
if (is_focused)
{
var visible_segment = new Segment(top_index, bottom_index - top_index + 1);
highlights = new Highlights( );
regex_engine.HighlightPattern(cnc, highlights, td.Text, td.SelectionStart, td.SelectionEnd, visible_segment);
}
if (cnc.IsCancellationRequested)
{
return;
}
lock ( Locker )
{
ChangeEventHelper.Invoke(CancellationToken.None, () =>
{
TryHighlight(ref LeftHighlightedParenthesis, highlights?.LeftPar ?? Segment.Empty, td, PatternParaHighlightStyleInfo);
if (cnc.IsCancellationRequested)
{
return;
}
TryHighlight(ref RightHighlightedParenthesis, highlights?.RightPar ?? Segment.Empty, td, PatternParaHighlightStyleInfo);
if (cnc.IsCancellationRequested)
{
return;
}
TryHighlight(ref LeftHighlightedBracket, highlights?.LeftBracket ?? Segment.Empty, td, PatternCharGroupBracketHighlightStyleInfo);
if (cnc.IsCancellationRequested)
{
return;
}
TryHighlight(ref RightHighlightedBracket, highlights?.RightBracket ?? Segment.Empty, td, PatternCharGroupBracketHighlightStyleInfo);
if (cnc.IsCancellationRequested)
{
return;
}
TryHighlight(ref LeftHighlightedCurlyBrace, highlights?.LeftCurlyBrace ?? Segment.Empty, td, PatternRangeCurlyBraceHighlightStyleInfo);
if (cnc.IsCancellationRequested)
{
return;
}
TryHighlight(ref RightHighlightedCurlyBrace, highlights?.RightCurlyBrace ?? Segment.Empty, td, PatternRangeCurlyBraceHighlightStyleInfo);
if (cnc.IsCancellationRequested)
{
return;
}
});
}
}
void RecolouringThreadProc(ICancellable cnc)
{
IRegexEngine regex_engine;
string eol;
lock (this)
{
regex_engine = mRegexEngine;
eol = mEol;
}
if (regex_engine == null)
{
return;
}
TextData td = null;
Rect clip_rect = Rect.Empty;
int top_index = 0;
int bottom_index = 0;
UITaskHelper.Invoke(rtb, () =>
{
td = null;
var start_doc = rtb.Document.ContentStart;
var end_doc = rtb.Document.ContentStart;
if (!start_doc.HasValidLayout || !end_doc.HasValidLayout)
{
return;
}
var td0 = rtb.GetTextData(eol);
if (cnc.IsCancellationRequested)
{
return;
}
td = td0;
clip_rect = new Rect(new Size(rtb.ViewportWidth, rtb.ViewportHeight));
TextPointer top_pointer = rtb.GetPositionFromPoint(new Point(0, 0), snapToText: true).GetLineStartPosition(-1, out int _);
if (cnc.IsCancellationRequested)
{
return;
}
top_index = td.TextPointers.GetIndex(top_pointer, LogicalDirection.Backward);
if (cnc.IsCancellationRequested)
{
return;
}
if (top_index < 0)
{
top_index = 0;
}
TextPointer bottom_pointer = rtb.GetPositionFromPoint(new Point(0, rtb.ViewportHeight), snapToText: true).GetLineStartPosition(+1, out int lines_skipped);
if (cnc.IsCancellationRequested)
{
return;
}
if (bottom_pointer == null || lines_skipped == 0)
{
bottom_index = td.Text.Length;
}
else
{
bottom_index = td.TextPointers.GetIndex(bottom_pointer, LogicalDirection.Forward);
if (cnc.IsCancellationRequested)
{
return;
}
}
if (bottom_index > td.Text.Length)
{
bottom_index = td.Text.Length;
}
if (bottom_index < top_index)
{
bottom_index = top_index; // (including 'if bottom_index == 0')
}
});
if (cnc.IsCancellationRequested)
{
return;
}
if (td == null)
{
return;
}
if (td.Text.Length == 0)
{
return;
}
Debug.Assert(top_index >= 0);
Debug.Assert(bottom_index >= top_index);
//Debug.Assert( bottom_index < td.OldPointers.Count );
Debug.Assert(bottom_index <= td.Text.Length);
var visible_segment = new Segment(top_index, bottom_index - top_index + 1);
var segments_to_colourise = new ColouredSegments( );
regex_engine.ColourisePattern(cnc, segments_to_colourise, td.Text, visible_segment);
if (cnc.IsCancellationRequested)
{
return;
}
int center_index = (top_index + bottom_index) / 2;
var arranged_escapes = segments_to_colourise.Escapes
.OrderBy(s => Math.Abs(center_index - (s.Index + s.Length / 2)))
.ToList( );
RtbUtilities.ApplyStyle(cnc, ChangeEventHelper, null, td, segments_to_colourise.Comments, PatternCommentStyleInfo);
RtbUtilities.ApplyStyle(cnc, ChangeEventHelper, null, td, arranged_escapes, PatternEscapeStyleInfo);
RtbUtilities.ApplyStyle(cnc, ChangeEventHelper, null, td, segments_to_colourise.GroupNames, PatternGroupNameStyleInfo);
var uncovered_segments = new List <Segment> {
new Segment(0, td.Text.Length)
};
foreach (var s in segments_to_colourise.All.SelectMany(s => s))
{
if (cnc.IsCancellationRequested)
{
return;
}
Segment.Except(uncovered_segments, s);
}
Segment.Except(uncovered_segments, LeftHighlightedParenthesis);
Segment.Except(uncovered_segments, RightHighlightedParenthesis);
Segment.Except(uncovered_segments, LeftHighlightedBracket);
Segment.Except(uncovered_segments, RightHighlightedBracket);
Segment.Except(uncovered_segments, LeftHighlightedCurlyBrace);
Segment.Except(uncovered_segments, RightHighlightedCurlyBrace);
var segments_to_uncolour =
uncovered_segments
.Select(s => Segment.Intersection(s, visible_segment))
.Where(s => !s.IsEmpty)
.OrderBy(s => Math.Abs(center_index - (s.Index + s.Length / 2)))
.ToList( );
if (cnc.IsCancellationRequested)
{
return;
}
RtbUtilities.ApplyStyle(cnc, ChangeEventHelper, null, td, segments_to_uncolour, PatternNormalStyleInfo);
}