hmtx table

Stores per-glyph horizontal metrics — advance width and left side bearing for each glyph.

Scope

• Format family: Shared SFNT
• Table tag in JSON: hmtx

Specs

• https://learn.microsoft.com/en-us/typography/opentype/spec/hmtx
• OpenType table registry: https://learn.microsoft.com/en-us/typography/opentype/spec/otff#font-tables

JSON Skeleton

This skeleton reflects fields currently parsed/written by Font Flux JS for this table.

{
  "tables": {
    "hmtx": {
      "hMetrics": null,
      "leftSideBearings": [],
      "_checksum": 0
    }
  }
}

Top-level Fields

• hMetrics - implementation-defined [spec type: LongHorMetric]
• leftSideBearings - array [spec type: FWORD]

Additional Nested Keys Seen In Implementation

• advanceWidth
• lsb

Notes

• Preserve _checksum for stable round-tripping.
• If a table is only partially understood, prefer keeping unknown bytes in _raw instead of dropping data.
• Validate with .validate() after edits.