hdmx table

Caches pre-computed horizontal device metrics (advance widths) at specific pixel sizes for faster rendering.

Scope

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

Specs

• (No explicit spec URL found in implementation source)
• 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": {
    "hdmx": {
      "version": 0,
      "records": null,
      "sizeDeviceRecord": 0,
      "_checksum": 0
    }
  }
}

Top-level Fields

• version - number (0..65535)
• records - implementation-defined
• sizeDeviceRecord - number

Additional Nested Keys Seen In Implementation

• None inferred from source.

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.