public void Add(byte[] ttf, float fontPixelHeight,
IEnumerable <CharacterRange> characterRanges)
{
if (ttf == null || ttf.Length == 0)
{
throw new ArgumentNullException(nameof(ttf));
}
if (fontPixelHeight <= 0)
{
throw new ArgumentOutOfRangeException(nameof(fontPixelHeight));
}
if (characterRanges == null)
{
throw new ArgumentNullException(nameof(characterRanges));
}
if (!characterRanges.Any())
{
throw new ArgumentException("characterRanges must have a least one value.");
}
var fontInfo = StbTrueType.CreateFont(ttf, 0);
if (fontInfo == null)
{
throw new Exception("Failed to init font.");
}
var scaleFactor = StbTrueType.stbtt_ScaleForPixelHeight(fontInfo, fontPixelHeight);
int ascent, descent, lineGap;
StbTrueType.stbtt_GetFontVMetrics(fontInfo, &ascent, &descent, &lineGap);
foreach (var range in characterRanges)
{
if (range.Start > range.End)
{
continue;
}
var cd = new StbTrueType.stbtt_packedchar[range.End - range.Start + 1];
fixed(StbTrueType.stbtt_packedchar *chardataPtr = cd)
{
StbTrueType.stbtt_PackFontRange(_context, fontInfo.data, 0, fontPixelHeight,
range.Start,
range.End - range.Start + 1,
chardataPtr);
}
for (var i = 0; i < cd.Length; ++i)
{
var yOff = cd[i].yoff;
yOff += ascent * scaleFactor;
var glyphInfo = new GlyphInfo
{
X = cd[i].x0,
Y = cd[i].y0,
Width = cd[i].x1 - cd[i].x0,
Height = cd[i].y1 - cd[i].y0,
XOffset = (int)cd[i].xoff,
YOffset = (int)Math.Round(yOff),
XAdvance = (int)Math.Round(cd[i].xadvance)
};
_glyphs[i + range.Start] = glyphInfo;
}
}
}