#pragma once

// TrueType outlines, as a font provider for include/text.h.
//
// Scope, and why it is this and not "TTF and OTF":
//
// .ttf and .otf are both sfnt containers -- the same table directory, the same
// cmap, the same hmtx. What differs is how outlines are stored. TrueType puts
// quadratic B-spline contours in a `glyf` table; OpenType/PostScript puts cubic
// béziers in a `CFF ` table encoded as Type 2 charstrings, which is a
// stack-based interpreted format and a separate project.
//
// Checked before writing any of it: JetBrains Mono and Roboto -- the two fonts
// this system is going to use -- both ship `glyf` and neither ships `CFF `. So
// CFF support would buy nothing today, and the honest thing is to implement the
// format the fonts actually use and say so, rather than half-implement two.
//
// Everything here is from Apple's TrueType Reference Manual and the OpenType
// specification, both public documents.

struct ttf {
  const unsigned char *data;
  uint32 len;

  uint32 glyf, glyf_len;
  uint32 loca, loca_len;
  uint32 cmap4;               // offset of the format 4 subtable, 0 if none
  uint32 hmtx;
  int    num_glyphs;
  int    num_hmetrics;
  int    units_per_em;
  int    long_loca;           // indexToLocFormat: 0 = 16-bit offsets, 1 = 32
  int    ascent, descent;

  // Rasterisation target size, in pixels per em. Set by ttf_open.
  int    px;
};

// Parse a font already in memory. Returns 0, or -1 if it is not a TrueType
// font this can read. `data` must outlive the struct -- nothing is copied.
int ttf_open(struct ttf *, const void *data, uint32 len, int pixels_per_em);

// Rasterise one codepoint into `cov`. Returns 0, or -1 if the font has no such
// glyph or it will not fit. Exposed because the host harness uses it directly.
int ttf_render(struct ttf *, uint32 cp, struct glyph *out, unsigned char *cov,
               int covcap, int *ox, int *oy);

// A font provider over it, for text.h. The struct must outlive the font.
struct font *ttf_font(struct ttf *);