Function CreatePath

src/rendering/renderers/TextPathRender.cpp:112–153

}

static std::unique_ptr<tgfx::PathMeasure> CreatePath(const PathData& pathData, float first,
                                                     float end) {
  auto pathMeasure = tgfx::PathMeasure::MakeFrom(ToPath(pathData));
  auto pathLength = pathMeasure->getLength();

  if (pathMeasure->isClosed() || (first >= 0 && end <= pathLength)) {
    return pathMeasure;
  }

  auto newPathData = pathData;

  if (first < 0) {
    tgfx::Point pos{};
    tgfx::Point tan{};
    newPathData.clear();

    auto remainLength = abs(first);
    // 获取起点的法线角度
    if (pathMeasure->getPosTan(0, &pos, &tan)) {
      auto x = pos.x - remainLength * tan.x;
      auto y = pos.y - remainLength * tan.y;

      newPathData.moveTo(x, y);
      newPathData.lineTo(pos.x, pos.y);
      AppendPathData(newPathData, pathData);
    }
  }

  if (end > pathLength) {
    tgfx::Point pos{};
    tgfx::Point tan{};

    auto remainLength = end - pathLength;
    // 获取最后一点的法线角度
    if (pathMeasure->getPosTan(pathLength, &pos, &tan)) {
      auto x = pos.x + remainLength * tan.x;
      auto y = pos.y + remainLength * tan.y;
      newPathData.lineTo(x, y);
    }
  }
  return tgfx::PathMeasure::MakeFrom(ToPath(newPathData));
}

static std::pair<float, float> FindMinMaxPathPosition(
    const TextPathLayout& pathLayout, const std::vector<std::vector<GlyphHandle>>& glyphLines) {