public new Result Shape(string text, float xOffset, float yOffset, SKPaint paint)
{
if (string.IsNullOrEmpty(text))
{
return(new Result());
}
using var buffer = new Buffer();
switch (paint.TextEncoding)
{
case SKTextEncoding.Utf8:
buffer.AddUtf8(text);
break;
case SKTextEncoding.Utf16:
buffer.AddUtf16(text);
break;
case SKTextEncoding.Utf32:
buffer.AddUtf32(text);
break;
default:
throw new NotSupportedException("TextEncoding of type GlyphId is not supported.");
}
buffer.GuessSegmentProperties();
return(Shape(buffer, xOffset, yOffset, paint));
}
public void ShouldAddUtfBySpan()
{
using (var buffer = new Buffer())
{
var utf8 = Encoding.UTF8.GetBytes("A").AsSpan();
buffer.AddUtf8(utf8);
Assert.Equal(1, buffer.Length);
var utf16 = "B".AsSpan();
buffer.AddUtf16(utf16);
Assert.Equal(2, buffer.Length);
var utf32 = new[] { char.ConvertToUtf32("C", 0) };
buffer.AddUtf32(utf32);
Assert.Equal(3, buffer.Length);
}
}
/// <summary>
/// Shape an array of utf-32 code points
/// </summary>
/// <param name="bufferSet">A re-usable text shaping buffer set that results will be allocated from</param>
/// <param name="codePoints">The utf-32 code points to be shaped</param>
/// <param name="style">The user style for the text</param>
/// <param name="direction">LTR or RTL direction</param>
/// <param name="clusterAdjustment">A value to add to all reported cluster numbers</param>
/// <param name="asFallbackFor">The type face this font is a fallback for</param>
/// <param name="textAlignment">The text alignment of the paragraph, used to control placement of glyphs within character cell when letter spacing used</param>
/// <returns>A TextShaper.Result representing the shaped text</returns>
public Result Shape(ResultBufferSet bufferSet, Slice <int> codePoints, IStyle style, TextDirection direction, int clusterAdjustment, SKTypeface asFallbackFor, TextAlignment textAlignment)
{
// Work out if we need to force this to a fixed pitch and if
// so the unscale character width we need to use
float forceFixedPitchWidth = 0;
if (asFallbackFor != _typeface && asFallbackFor != null)
{
var originalTypefaceShaper = ForTypeface(asFallbackFor);
if (originalTypefaceShaper._isFixedPitch)
{
forceFixedPitchWidth = originalTypefaceShaper._fixedCharacterWidth;
}
}
// Work out how much to shift glyphs in the character cell when using letter spacing
// The idea here is to align the glyphs within the character cell the same way as the
// text block alignment so that left/right aligned text still aligns with the margin
// and centered text is still centered (and not shifted slightly due to the extra
// space that would be at the right with normal letter spacing).
float glyphLetterSpacingAdjustment = 0;
switch (textAlignment)
{
case TextAlignment.Right:
glyphLetterSpacingAdjustment = style.LetterSpacing;
break;
case TextAlignment.Center:
glyphLetterSpacingAdjustment = style.LetterSpacing / 2;
break;
}
using (var buffer = new HarfBuzzSharp.Buffer())
{
// Setup buffer
buffer.AddUtf32(new ReadOnlySpan <int>(codePoints.Underlying, codePoints.Start, codePoints.Length), 0, -1);
// Setup directionality (if supplied)
switch (direction)
{
case TextDirection.LTR:
buffer.Direction = Direction.LeftToRight;
break;
case TextDirection.RTL:
buffer.Direction = Direction.RightToLeft;
break;
default:
throw new ArgumentException(nameof(direction));
}
// Guess other attributes
buffer.GuessSegmentProperties();
// Shape it
_font.Shape(buffer);
// RTL?
bool rtl = buffer.Direction == Direction.RightToLeft;
// Work out glyph scaling and offsetting for super/subscript
float glyphScale = style.FontSize / overScale;
float glyphVOffset = 0;
if (style.FontVariant == FontVariant.SuperScript)
{
glyphScale *= 0.65f;
glyphVOffset -= style.FontSize * 0.35f;
}
if (style.FontVariant == FontVariant.SubScript)
{
glyphScale *= 0.65f;
glyphVOffset += style.FontSize * 0.1f;
}
// Create results and get buffes
var r = new Result();
r.GlyphIndicies = bufferSet.GlyphIndicies.Add((int)buffer.Length, false);
r.GlyphPositions = bufferSet.GlyphPositions.Add((int)buffer.Length, false);
r.Clusters = bufferSet.Clusters.Add((int)buffer.Length, false);
r.CodePointXCoords = bufferSet.CodePointXCoords.Add(codePoints.Length, false);
r.CodePointXCoords.Fill(0);
// Convert points
var gp = buffer.GlyphPositions;
var gi = buffer.GlyphInfos;
float cursorX = 0;
float cursorY = 0;
float cursorXCluster = 0;
for (int i = 0; i < buffer.Length; i++)
{
r.GlyphIndicies[i] = (ushort)gi[i].Codepoint;
r.Clusters[i] = (int)gi[i].Cluster + clusterAdjustment;
// Update code point positions
if (!rtl)
{
// First cluster, different cluster, or same cluster with lower x-coord
if (i == 0 ||
(r.Clusters[i] != r.Clusters[i - 1]) ||
(cursorX < r.CodePointXCoords[r.Clusters[i] - clusterAdjustment]))
{
r.CodePointXCoords[r.Clusters[i] - clusterAdjustment] = cursorX;
}
}
// Get the position
var pos = gp[i];
// Update glyph position
r.GlyphPositions[i] = new SKPoint(
cursorX + pos.XOffset * glyphScale + glyphLetterSpacingAdjustment,
cursorY - pos.YOffset * glyphScale + glyphVOffset
);
// Update cursor position
cursorX += pos.XAdvance * glyphScale;
cursorY += pos.YAdvance * glyphScale;
if (i + 1 == gi.Length || gi[i].Cluster != gi[i + 1].Cluster)
{
cursorX += style.LetterSpacing;
}
// Are we falling back for a fixed pitch font and is the next character a
// new cluster? If so advance by the width of the original font, not this
// fallback font
if (forceFixedPitchWidth != 0)
{
// New cluster?
if (i + 1 >= buffer.Length || gi[i].Cluster != gi[i + 1].Cluster)
{
// Work out fixed pitch position of next cluster
cursorXCluster += forceFixedPitchWidth * glyphScale;
if (cursorXCluster > cursorX)
{
// Nudge characters to center them in the fixed pitch width
if (i == 0 || gi[i - 1].Cluster != gi[i].Cluster)
{
r.GlyphPositions[i].X += (cursorXCluster - cursorX) / 2;
}
// Use fixed width character position
cursorX = cursorXCluster;
}
else
{
// Character is wider (probably an emoji) so we
// allow it to exceed the fixed pitch character width
cursorXCluster = cursorX;
}
}
}
// Store RTL cursor position
if (rtl)
{
// First cluster, different cluster, or same cluster with lower x-coord
if (i == 0 ||
(r.Clusters[i] != r.Clusters[i - 1]) ||
(cursorX > r.CodePointXCoords[r.Clusters[i] - clusterAdjustment]))
{
r.CodePointXCoords[r.Clusters[i] - clusterAdjustment] = cursorX;
}
}
}
// Finalize cursor positions by filling in any that weren't
// referenced by a cluster
if (rtl)
{
r.CodePointXCoords[0] = cursorX;
for (int i = codePoints.Length - 2; i >= 0; i--)
{
if (r.CodePointXCoords[i] == 0)
{
r.CodePointXCoords[i] = r.CodePointXCoords[i + 1];
}
}
}
else
{
for (int i = 1; i < codePoints.Length; i++)
{
if (r.CodePointXCoords[i] == 0)
{
r.CodePointXCoords[i] = r.CodePointXCoords[i - 1];
}
}
}
// Also return the end cursor position
r.EndXCoord = new SKPoint(cursorX, cursorY);
// And some other useful metrics
r.Ascent = _fontMetrics.Ascent * style.FontSize / overScale;
r.Descent = _fontMetrics.Descent * style.FontSize / overScale;
r.XMin = _fontMetrics.XMin * style.FontSize / overScale;
// Done
return(r);
}
}