public static IEnumerable <Run> GetFontRuns(Slice <int> codePoints, SKTypeface typeface)
{
var fontManager = SKFontManager.Default;
int currentRunPos = 0;
SKTypeface currentRunTypeface = null;
int pos = 0;
List <Run> runs = new List <Run>();
unsafe
{
fixed(int *pCodePoints = codePoints.Underlying)
{
int *pch = pCodePoints + codePoints.Start;
int length = codePoints.Length;
while (pos < length)
{
var RunFace = typeface;
int count = 0;
if (pch[pos] <= 32)
{
// Control characters and space always map to current typeface
count = 1;
RunFace = currentRunTypeface ?? typeface;
}
else
{
// Consume as many characters as possible using the requested type face
count = typeface.GetGlyphs((IntPtr)(pch + pos), length - pos, SKEncoding.Utf32, out var glyphs);
}
// Couldn't be mapped to current font, try to find a replacement
if (count == 0)
{
// Find fallback font
RunFace = fontManager.MatchCharacter(typeface.FamilyName, typeface.FontWeight, typeface.FontWidth, typeface.FontSlant, null, pch[pos]);
// If couldn't use the specified font
if (RunFace == null)
{
RunFace = typeface;
}
// Consume as many characters as possible using the requested type face
count = 1;// RunFace.GetGlyphs((IntPtr)(pch + pos), length - pos, SKEncoding.Utf32, out var glyphs);
}
// Do we need to start a new Run?
if (currentRunTypeface != RunFace)
{
flushCurrentRun();
currentRunTypeface = RunFace;
currentRunPos = pos;
}
// Move on
pos += count;
}
}
}
// Flush the final Run
flushCurrentRun();
// Done
return(runs);
void flushCurrentRun()
{
if (currentRunTypeface != null)
{
runs.Add(new Run()
{
Start = currentRunPos,
Length = pos - currentRunPos,
Typeface = currentRunTypeface,
});
}
}
}