Feature/embeddable fonts v3

[swmal]

Fonts supporting GSUB/GPOS tables (ligatures, kerning, mark-to-base, etc), subsetting. New TextShaper and TextLayoutEngine.

TextShaper

Advanced OpenType text shaping with GSUB/GPOS support. Returns shaped glyphs with positioning, ligatures, kerning, and mark placement for typography.

var font = OpenTypeFonts.GetFontData(FontFolders, "Roboto", FontSubFamily.Regular);
ITextShaper shaper = new TextShaper(font);
// Returns ShapedText (a collection of ShapedGlyphs).
ShapedText st= shaper.Shape("Test");
var taw = st.TotalAdvanceWidth;
foreach(var shapedGlyph in st.Glyphs)
{
   var gid = shapedGlyph.GlyphId;
   var xa = shapedGlyph.XAdvance;
   var cc = shapedGlyph.CharCount;
}

// memory optimized method for measurements
GlyphWidth[] gw = shaper.ShapeLight("Test", ShapingOptions.Full);

OpenTypeTextMeasurer

Implements the "old" ITextMeasurer interface. Wrapping is now the responsibility of the TextLayoutEngine (see below).

var font = OpenTypeFonts.GetFontData(FontFolders, "Roboto", FontSubFamily.Regular);
ITextShaper shaper = new TextShaper(font);
ITextMeasurer measurer = new OpenTypeFontTextMeasurer(shaper, ShapingOptions.Default);

TextLayoutEngine

High-performance text layout engine with line breaking, word wrapping, and paragraph formatting. Handles rich text with multiple fonts and styles, font metrics, advance widths, line heights, and multi-line text rendering for professional typography.

var font = OpenTypeFonts.GetFontData(FontFolders, "Roboto", FontSubFamily.Regular);
ITextShaper shaper = new TextShaper(font);
using var layoutEngine = new TextLayoutEngine(shaper);
var wrappedLines = layoutEngine.WrapText(
    "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus eget urna at sapien facilisis placerat. Integer mollis nibh vel tincidunt metus.",
    14f,
    450,
    ShapingOptions.Full
);
double lh = layoutEngine.GetLineHeightInPoints(14);
double bl = layoutEngine.GetBaseLineInPoints(14);
double d = layoutEngine.GetDescentInPoints(14);

EPPlus.Fonts.OpenType.Tests

Contains 200+ unit tests covering reading, serialization, subsetting and text-shaping.

EPPlus.Fonts.OpenType.Benchmarks

Performance benchmarking suite for measuring text shaping, layout, and font operations. Includes benchmarks for glyph shaping speed, memory allocation, cache performance, and comparison against baseline implementations for optimization tracking.

Previous tests with benchmark functionality (measured time, etc) has been moved from the Unit test project to the new Benchmark project.