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Check Glyph Coverage Before Choosing Fallbacks

Before you wire up fallback families, it helps to know what your primary font can already cover. This recipe shows a quick way to probe individual scalar values with Font.TryGetGlyphs(...) or scan a string so you can make fallback decisions based on actual glyph coverage instead of guesswork.

Check individual code points

using SixLabors.Fonts;
using SixLabors.Fonts.Unicode;

Font font = SystemFonts.CreateFont("Segoe UI", 16);

bool hasLatinA = font.TryGetGlyphs(new CodePoint('A'), out _);
bool hasOmega = font.TryGetGlyphs(new CodePoint(0x03A9), out _); // Ω GREEK CAPITAL LETTER OMEGA
bool hasEmoji = font.TryGetGlyphs(new CodePoint(0x1F600), out _); // 😀 GRINNING FACE

Scan a whole string for missing glyphs

using System.Collections.Generic;
using SixLabors.Fonts;
using SixLabors.Fonts.Unicode;

string text = "Hello 123 مرحبا 😀";
Font font = SystemFonts.CreateFont("Segoe UI", 16);
List<CodePoint> missing = new();

foreach (CodePoint codePoint in text.AsSpan().EnumerateCodePoints())
{
    if (!font.TryGetGlyphs(codePoint, out _))
    {
        missing.Add(codePoint);
    }
}

This is a simple way to decide whether you need FallbackFontFamilies before you measure or render the text.

If you want a broader face-level view instead of checking a specific string, use Font.FontMetrics.GetAvailableCodePoints().

Glyph coverage is only the first question. A font can contain glyphs for individual code points but still lack the shaping behavior, marks, variation sequences, or color glyph data needed for the text to look right in a real script. Use coverage checks to choose candidate fallback families, then measure or render with the same TextOptions you will use in production.

Emoji and complex scripts are the usual cases where this distinction matters. A visible emoji can be a grapheme made from several code points, and Arabic, Indic, or Southeast Asian scripts can require shaping features that are not captured by a one-code-point probe.

For the conceptual fallback guidance, see Fallback Fonts and Multilingual Text. For face-level coverage inspection, see Font Metrics.

Practical guidance

  • Use coverage checks to choose fallback candidates, not to prove final rendered quality.
  • Test grapheme clusters such as emoji sequences as whole strings with production layout options.
  • Prefer face-level coverage inspection when building diagnostics or font picker tooling.
  • Keep fallback order intentional so broad-coverage fonts do not hide preferred design choices.
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