/// <summary>
/// Splits the <see cref="TextRun"/> at specified length.
/// </summary>
/// <param name="length">The length.</param>
/// <returns>The split result.</returns>
public SplitTextCharactersResult Split(int length)
{
var glyphCount = 0;
var firstCharacters = GlyphRun.Characters.Take(length);
var codepointEnumerator = new CodepointEnumerator(firstCharacters);
while (codepointEnumerator.MoveNext())
{
glyphCount++;
}
if (GlyphRun.Characters.Length == length)
{
return(new SplitTextCharactersResult(this, null));
}
if (GlyphRun.GlyphIndices.Length == glyphCount)
{
return(new SplitTextCharactersResult(this, null));
}
var firstGlyphRun = new GlyphRun(
Properties.Typeface.GlyphTypeface,
Properties.FontRenderingEmSize,
GlyphRun.GlyphIndices.Take(glyphCount),
GlyphRun.GlyphAdvances.Take(glyphCount),
GlyphRun.GlyphOffsets.Take(glyphCount),
GlyphRun.Characters.Take(length),
GlyphRun.GlyphClusters.Take(glyphCount));
var firstTextRun = new ShapedTextCharacters(firstGlyphRun, Properties);
var secondGlyphRun = new GlyphRun(
Properties.Typeface.GlyphTypeface,
Properties.FontRenderingEmSize,
GlyphRun.GlyphIndices.Skip(glyphCount),
GlyphRun.GlyphAdvances.Skip(glyphCount),
GlyphRun.GlyphOffsets.Skip(glyphCount),
GlyphRun.Characters.Skip(length),
GlyphRun.GlyphClusters.Skip(glyphCount));
var secondTextRun = new ShapedTextCharacters(secondGlyphRun, Properties);
return(new SplitTextCharactersResult(firstTextRun, secondTextRun));
}
/// <summary>
/// Creates a shapeable text run with unique properties.
/// </summary>
/// <param name="text">The text to create text runs from.</param>
/// <param name="defaultProperties">The default text run properties.</param>
/// <param name="biDiLevel">The bidi level of the run.</param>
/// <param name="previousProperties"></param>
/// <returns>A list of shapeable text runs.</returns>
private static ShapeableTextCharacters CreateShapeableRun(ReadOnlySlice <char> text,
TextRunProperties defaultProperties, sbyte biDiLevel, ref TextRunProperties?previousProperties)
{
var defaultTypeface = defaultProperties.Typeface;
var currentTypeface = defaultTypeface;
var previousTypeface = previousProperties?.Typeface;
if (TryGetShapeableLength(text, currentTypeface, null, out var count, out var script))
{
if (script == Script.Common && previousTypeface is not null)
{
if (TryGetShapeableLength(text, previousTypeface.Value, defaultTypeface, out var fallbackCount, out _))
{
return(new ShapeableTextCharacters(text.Take(fallbackCount),
defaultProperties.WithTypeface(previousTypeface.Value), biDiLevel));
}
}
return(new ShapeableTextCharacters(text.Take(count), defaultProperties.WithTypeface(currentTypeface),
biDiLevel));
}
if (previousTypeface is not null)
{
if (TryGetShapeableLength(text, previousTypeface.Value, defaultTypeface, out count, out _))
{
return(new ShapeableTextCharacters(text.Take(count),
defaultProperties.WithTypeface(previousTypeface.Value), biDiLevel));
}
}
var codepoint = Codepoint.ReplacementCodepoint;
var codepointEnumerator = new CodepointEnumerator(text.Skip(count));
while (codepointEnumerator.MoveNext())
{
if (codepointEnumerator.Current.IsWhiteSpace)
{
continue;
}
codepoint = codepointEnumerator.Current;
break;
}
//ToDo: Fix FontFamily fallback
var matchFound =
FontManager.Current.TryMatchCharacter(codepoint, defaultTypeface.Style, defaultTypeface.Weight,
defaultTypeface.Stretch, defaultTypeface.FontFamily, defaultProperties.CultureInfo,
out currentTypeface);
if (matchFound && TryGetShapeableLength(text, currentTypeface, defaultTypeface, out count, out _))
{
//Fallback found
return(new ShapeableTextCharacters(text.Take(count), defaultProperties.WithTypeface(currentTypeface),
biDiLevel));
}
// no fallback found
currentTypeface = defaultTypeface;
var glyphTypeface = currentTypeface.GlyphTypeface;
var enumerator = new GraphemeEnumerator(text);
while (enumerator.MoveNext())
{
var grapheme = enumerator.Current;
if (!grapheme.FirstCodepoint.IsWhiteSpace && glyphTypeface.TryGetGlyph(grapheme.FirstCodepoint, out _))
{
break;
}
count += grapheme.Text.Length;
}
return(new ShapeableTextCharacters(text.Take(count), defaultProperties, biDiLevel));
}
