Jazz2::UI::FontFormat struct
#include <Jazz2/UI/FontFormat.h>

On-disk layout of a packed font.

A font is a single self-contained file: the glyph metrics and the glyph atlas together, the atlas in the same QOI-based encoding every other image asset uses, all of it deflated. It holds one palette index per pixel rather than the expanded colours the old two-file (.png + .png.font) form carried, which cost four bytes per pixel on disk and again in memory.

A font is entirely index based: every pixel either names a palette color or is index 0 and draws nothing. There is no per-pixel coverage - the shading of a glyph comes from the colors it names, not from blending it into what is behind it - so the packer resolves anything in between and says so.

Glyphs are packed tightly: every one is measured to its actual inked area rather than sitting in a fixed cell, and each keeps a bearing so it still lands where it belongs on the line. A one pixel margin is left around each - so neighbours are two pixels apart - which is what stops bilinear sampling from bleeding one glyph into the next, the same margin the sprite sheets leave around each frame.

The layout is:

  • Signature, ContentFileType::Font, CurrentVersion and a flags byte
  • the size of the deflated block that follows, everything below being inside it
  • the atlas size, the line height, the base spacing and the character counts
  • a Glyph for each ASCII character, then a codepoint and a Glyph for each Unicode one
  • the atlas itself, one palette index per pixel

Public types

struct Glyph
Metrics of a single glyph.

Public static variables

static std::uint64_t Signature constexpr
Signature shared by the game's own file formats.
static std::uint8_t CurrentVersion constexpr
Version of the layout described here.
static std::int32_t GlyphMargin constexpr
Margin left around every glyph, in pixels (so neighbours are two pixels apart).
static std::uint32_t FallbackCodepoint constexpr
Codepoint of the glyph drawn in place of a character the font doesn't have.
static std::int32_t MaxGlyphSize constexpr
Largest glyph box the record above can describe.
static std::int32_t MaxGlyphBearing constexpr
Largest bearing (in absolute value) the record above can describe.