core/fxge/skrifa/src/outlines.cpp

// Copyright 2026 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// Based on https://github.com/googlefonts/fontations/pull/1820

#include "core/fxge/skrifa/src/outlines.h"

#include <stdio.h>
#include <string.h>

#include <fstream>
#include <iterator>
#include <string>
#include <string_view>
#include <vector>

#include "core/fxge/skrifa/src/main.rs.h"

void dump_outline(skrifa::Outline& outline);

void skrifa::run(rust::Str font_path) {
  // Load the font data
  std::string path_str(font_path.data(), font_path.size());
  std::ifstream input(path_str, std::ios::binary);
  std::vector<uint8_t> bytes((std::istreambuf_iterator<char>(input)),
                             (std::istreambuf_iterator<char>()));
  input.close();

  rust::Slice<const uint8_t> slice(bytes);

  // Load the font. Note that the bytes vector must live as long as the font
  auto font = skrifa::new_font(slice, 0);
  if (!font->is_ok()) {
    printf("Failed to load font!\n");
    return;
  }

  // Get the PostScript name
  std::string name(font->postscript_name());

  // And the family name
  auto family_name = std::string(font->family_name());

  printf("ps name = %s, family name = %s\n", name.c_str(), family_name.c_str());

  // How many glyphs?
  printf("Font has %d glyphs\n", font->num_glyphs());

  // The font's encoding is Adobe standard
  assert(font->encoding() == PsEncodingKind::Standard);

  // The Adobe standard code for 'x' is 120
  auto gid_from_code = font->code_to_gid(120);

  // But we also generate a Unicode mapping for glyphs present in the AGL
  auto gid = font->unicode_to_gid('x');

  assert(gid_from_code == gid);

  // Storage for our outline
  skrifa::Outline outline;

  // Load an unscaled outline
  font->unscaled_outline(gid, outline);
  dump_outline(outline);

  // Load the same outline at 16px
  font->scaled_outline(gid, 16.0, outline);
  dump_outline(outline);

  // Convert glyph name to unicode
  uint32_t period_unicode;
  assert(skrifa::agl_name_to_unicode("period", period_unicode));
  assert(period_unicode == '.');

  // Convert unicode to glyph name
  uint8_t period_name[64] = {};
  assert(
      skrifa::agl_unicode_to_name('.', rust::Slice<uint8_t>(period_name, 40)));
  assert(std::string_view(reinterpret_cast<const char*>(&period_name[0])) ==
         "period");
}

void dump_outline(skrifa::Outline& outline) {
  auto point_idx = 0;
  for (auto verb : outline.verbs) {
    switch (verb) {
      case skrifa::PathVerb::MoveTo: {
        auto p = outline.points[point_idx];
        point_idx += 1;
        printf("M%f,%f ", p.x, p.y);
        break;
      }
      case skrifa::PathVerb::LineTo: {
        auto p = outline.points[point_idx];
        point_idx += 1;
        printf("L%f,%f ", p.x, p.y);
        break;
      }
      case skrifa::PathVerb::QuadTo: {
        auto c0 = outline.points[point_idx];
        auto p = outline.points[point_idx + 1];
        point_idx += 2;
        printf("Q%f,%f %f,%f ", c0.x, c0.y, p.x, p.y);
        break;
      }
      case skrifa::PathVerb::CurveTo: {
        auto c0 = outline.points[point_idx];
        auto c1 = outline.points[point_idx + 1];
        auto p = outline.points[point_idx + 2];
        point_idx += 3;
        printf("C%f,%f %f,%f %f,%f ", c0.x, c0.y, c1.x, c1.y, p.x, p.y);
        break;
      }
      case skrifa::PathVerb::Close:
        printf("Z");
        break;
      default:
        break;
    }
  }
  printf("\nadvance = %f\n", outline.advance_width);
}