private const int HORIZONTAL_OFFSET = 2; //Reduces artifacts when scaling up
/// <summary>
/// Generate a font from a font file.
/// </summary>
/// <param name="fontFileName">Name of the font file</param>
/// <param name="fontSize">Size of the bitmap font</param>
/// <param name="lowerChar">The lowest character to render</param>
/// <param name="upperChar">The hightest character</param>
/// <returns>A description for the font</returns>
public static FontDescription GenerateFont(string fontFileName, float fontSize, char lowerChar = (char)32, char upperChar = (char)127)
{
var font = new FontFace(File.OpenRead(fontFileName));
var glyphs = new Dictionary <char, (GlyphLayout, Glyph)>();
var currentX = 0;
var currentY = 0;
var maxY = 0;
for (char i = lowerChar; i < upperChar; i++)
{
var glyph = font.GetGlyph(new CodePoint(i), fontSize);
int w = glyph.RenderWidth;
int h = glyph.RenderHeight;
//Glyph would be to big
if (currentX + w + HORIZONTAL_OFFSET > MAX_BITMAP_WIDTH)
{
currentY += maxY;
maxY = 0;
currentX = 0;
}
//Glyph is biggest in its line
if (h > maxY)
{
maxY = h;
}
IntRect?region;
if (w == 0 || h == 0)
{
//Glyph is invisible, so it has no region on the bitmap
region = null;
}
else
{
region = new IntRect(currentX, currentY, w, h);
}
var layout = new GlyphLayout(i, region, new Vector2(glyph.Width, glyph.Height), glyph.HorizontalMetrics.Bearing, glyph.HorizontalMetrics.Advance);
currentX += w + HORIZONTAL_OFFSET;
glyphs.Add(i, (layout, glyph));
}
var finalHeight = currentY + maxY;
var bitmap = new Image <Rgba32>(MAX_BITMAP_WIDTH, finalHeight);
var glyphTable = new Dictionary <char, GlyphLayout>();
bitmap.Mutate(ctx =>
{
foreach (var glyphEntry in glyphs)
{
var(layout, glyph) = glyphEntry.Value;
if (layout.BitmapRegion.HasValue)
{
//Glyph is renderable
var region = layout.BitmapRegion.Value;
var pos = new Point(region.X, region.Y);
var img = RenderGlyph(glyph);
ctx.DrawImage(img, 1f, pos);
}
glyphTable[glyphEntry.Key] = layout;
}
});
var metadata = new FontMetadata(
font.Family,
font.Subfamily,
fontSize,
FontMetadata.StyleFrom(font.Style),
(int)font.Weight,
FontMetadata.StretchFrom(font.Stretch));
return(new FontDescription(metadata, bitmap, new Glyphs(glyphTable)));
}
public FontDescription(FontMetadata metadata, Image <Rgba32> bitmap, Glyphs glyphs)
{
Metadata = metadata;
Bitmap = bitmap;
Glyphs = glyphs;
}