ca-svg.H

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/*
                          Aleph_w
 
  Data structures & Algorithms
  version 2.0.0b
  https://github.com/lrleon/Aleph-w
 
  This file is part of Aleph-w library
 
  Copyright (c) 2002-2026 Leandro Rabindranath Leon
 
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
 
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
 
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/
 
#ifndef CA_SVG_H
#define CA_SVG_H
 
#include <array>
#include <cmath>
#include <concepts>
#include <cstdint>
#include <filesystem>
#include <fstream>
#include <limits>
#include <ostream>
#include <sstream>
#include <string>
#include <utility>
 
#include <ah-errors.H>
#include <tpl_array.H>
 
#include <ca-frame-stream.H>
#include <ca-io.H>
#include <tpl_ca_concepts.H>
#include <tpl_ca_hex_lattice.H>
#include <tpl_ca_triangular_lattice.H>
 
namespace Aleph {
namespace CA {
 
struct SVG_Render_Options
{
  double cell_size = 18.0;            
  double stroke_width = 0.75;         
  bool draw_grid = true;              
  bool omit_dead_cells = false;       
  RGB8 stroke_colour{190, 190, 190};  
};
 
namespace ca_svg_detail {
 
[[nodiscard]] inline std::string rgb_hex(const RGB8 c)
{
  constexpr char digits[] = "0123456789abcdef";
  std::string out = "#000000";
  out[1] = digits[c.r >> 4];
  out[2] = digits[c.r & 0x0f];
  out[3] = digits[c.g >> 4];
  out[4] = digits[c.g & 0x0f];
  out[5] = digits[c.b >> 4];
  out[6] = digits[c.b & 0x0f];
  return out;
}
 
struct Bounds
{
  double min_x = std::numeric_limits<double>::infinity();
  double min_y = std::numeric_limits<double>::infinity();
  double max_x = -std::numeric_limits<double>::infinity();
  double max_y = -std::numeric_limits<double>::infinity();
 
  void include(const double x, const double y) noexcept
  {
    min_x = std::min(min_x, x);
    min_y = std::min(min_y, y);
    max_x = std::max(max_x, x);
    max_y = std::max(max_y, y);
  }
};
 
inline void write_svg_header(std::ostream &out, const Bounds &b, const SVG_Render_Options &opts)
{
  const double pad = opts.draw_grid ? opts.stroke_width : 0.0;
  const double x = b.min_x - pad;
  const double y = b.min_y - pad;
  const double w = std::max(1.0, b.max_x - b.min_x + 2.0 * pad);
  const double h = std::max(1.0, b.max_y - b.min_y + 2.0 * pad);
  out << "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";
  out << "<svg xmlns=\"http://www.w3.org/2000/svg\" viewBox=\"" << x << ' ' << y << ' ' << w << ' '
      << h << "\" width=\"" << w << "\" height=\"" << h << "\">\n";
}
 
inline void write_style(std::ostream &out, const SVG_Render_Options &opts)
{
  if (opts.draw_grid)
    out << " stroke=\"" << rgb_hex(opts.stroke_colour) << "\" stroke-width=\"" << opts.stroke_width
        << '"';
  else
    out << " stroke=\"none\"";
}
 
inline void write_points(std::ostream &out, const Array<std::array<double, 2>> &pts)
{
  for (std::size_t i = 0; i < pts.size(); ++i)
    {
      if (i != 0)
        out << ' ';
      out << pts(i)[0] << ',' << pts(i)[1];
    }
}
 
[[nodiscard]] inline Array<std::array<double, 2>> hex_points(Hex_Axial a, const double radius)
{
  const auto centre = axial_to_pixel_pointy(a, radius);
  Array<std::array<double, 2>> pts(6);
  for (int k = 0; k < 6; ++k)
    {
      constexpr double pi = 3.14159265358979323846;
      const double angle = (60.0 * static_cast<double>(k) - 30.0) * pi / 180.0;
      pts.append(std::array<double, 2>{centre[0] + radius * std::cos(angle),
                                       centre[1] + radius * std::sin(angle)});
    }
  return pts;
}
 
[[nodiscard]] inline Array<std::array<double, 2>> tri_points(Tri_Coord c, const double side)
{
  constexpr double sqrt3 = 1.7320508075688772;
  const double h = side * sqrt3 / 2.0;
  const auto centre = tri_pixel_centre(c, side);
  // Built with explicit appends: Array(3) preallocates exact capacity,
  // and the three vertices read clearer than a braced list-init.
  using Pt = std::array<double, 2>;
  Array<Pt> pts(3);
  if (tri_is_up(c))
    {
      pts.append(Pt{centre[0], centre[1] - (2.0 * h / 3.0)});
      pts.append(Pt{centre[0] - side / 2.0, centre[1] + h / 3.0});
      pts.append(Pt{centre[0] + side / 2.0, centre[1] + h / 3.0});
    }
  else
    {
      pts.append(Pt{centre[0], centre[1] + (2.0 * h / 3.0)});
      pts.append(Pt{centre[0] - side / 2.0, centre[1] - h / 3.0});
      pts.append(Pt{centre[0] + side / 2.0, centre[1] - h / 3.0});
    }
  return pts;
}
 
}  // namespace ca_svg_detail
 
template <typename Lattice, typename Palette>
inline void render_lattice_svg(std::ostream &out,
                               const Lattice &frame,
                               Palette &&palette,
                               const SVG_Render_Options &opts = {},
                               const typename Lattice::state_type &dead_state
                               = typename Lattice::state_type{})
  requires requires(Palette &&p, const typename Lattice::state_type &v) {
    { p(v) } -> std::convertible_to<RGB8>;
  }
{
  static_assert(LatticeLike<Lattice>, "render_lattice_svg requires a LatticeLike frame");
  static_assert(Lattice::rank == 2, "render_lattice_svg requires a rank-2 frame");
  ah_domain_error_if(opts.cell_size <= 0.0) << "render_lattice_svg: cell_size must be positive";
 
  ca_svg_detail::Bounds b;
  if constexpr (HexRenderable<Lattice>)
    {
      for (ca_size_t r = 0; r < frame.rows(); ++r)
        for (ca_size_t q = 0; q < frame.cols(); ++q)
          for (const auto &p : ca_svg_detail::hex_points(
                 Hex_Axial{static_cast<ca_index_t>(q), static_cast<ca_index_t>(r)}, opts.cell_size))
            b.include(p[0], p[1]);
      // Empty hex grid → seed a degenerate but finite box so the SVG
      // header does not serialise inf/nan.
      if (frame.rows() == 0 or frame.cols() == 0)
        {
          b.include(0.0, 0.0);
          b.include(static_cast<double>(frame.cols()) * opts.cell_size,
                    static_cast<double>(frame.rows()) * opts.cell_size);
        }
    }
  else if constexpr (TriRenderable<Lattice>)
    {
      for (ca_size_t r = 0; r < frame.rows(); ++r)
        for (ca_size_t c = 0; c < frame.cols(); ++c)
          for (const auto &p : ca_svg_detail::tri_points(
                 Tri_Coord{static_cast<ca_index_t>(r), static_cast<ca_index_t>(c)}, opts.cell_size))
            b.include(p[0], p[1]);
      if (frame.rows() == 0 or frame.cols() == 0)
        {
          b.include(0.0, 0.0);
          b.include(static_cast<double>(frame.cols()) * opts.cell_size,
                    static_cast<double>(frame.rows()) * opts.cell_size);
        }
    }
  else
    {
      b.include(0.0, 0.0);
      b.include(static_cast<double>(frame.size(1)) * opts.cell_size,
                static_cast<double>(frame.size(0)) * opts.cell_size);
    }
 
  ca_svg_detail::write_svg_header(out, b, opts);
  if constexpr (HexRenderable<Lattice>)
    {
      for (ca_size_t r = 0; r < frame.rows(); ++r)
        for (ca_size_t q = 0; q < frame.cols(); ++q)
          {
            const Hex_Axial a{static_cast<ca_index_t>(q), static_cast<ca_index_t>(r)};
            const auto state = frame.at_axial(a);
            if (opts.omit_dead_cells and state == dead_state)
              continue;
            out << "  <polygon points=\"";
            ca_svg_detail::write_points(out, ca_svg_detail::hex_points(a, opts.cell_size));
            out << "\" fill=\"" << ca_svg_detail::rgb_hex(palette(state)) << '"';
            ca_svg_detail::write_style(out, opts);
            out << "/>\n";
          }
    }
  else if constexpr (TriRenderable<Lattice>)
    {
      for (ca_size_t r = 0; r < frame.rows(); ++r)
        for (ca_size_t c = 0; c < frame.cols(); ++c)
          {
            const Tri_Coord tc{static_cast<ca_index_t>(r), static_cast<ca_index_t>(c)};
            const auto state = frame.at_tri(tc);
            if (opts.omit_dead_cells and state == dead_state)
              continue;
            out << "  <polygon points=\"";
            ca_svg_detail::write_points(out, ca_svg_detail::tri_points(tc, opts.cell_size));
            out << "\" fill=\"" << ca_svg_detail::rgb_hex(palette(state)) << '"';
            ca_svg_detail::write_style(out, opts);
            out << "/>\n";
          }
    }
  else
    {
      using coord_t = typename Lattice::coord_type;
      for (ca_size_t r = 0; r < frame.size(0); ++r)
        for (ca_size_t c = 0; c < frame.size(1); ++c)
          {
            const auto state
              = frame.at(coord_t{static_cast<ca_index_t>(r), static_cast<ca_index_t>(c)});
            if (opts.omit_dead_cells and state == dead_state)
              continue;
            out << "  <rect x=\"" << static_cast<double>(c) * opts.cell_size << "\" y=\""
                << static_cast<double>(r) * opts.cell_size << "\" width=\"" << opts.cell_size
                << "\" height=\"" << opts.cell_size << "\" fill=\""
                << ca_svg_detail::rgb_hex(palette(state)) << '"';
            ca_svg_detail::write_style(out, opts);
            out << "/>\n";
          }
    }
  out << "</svg>\n";
  ah_runtime_error_if(not out) << "render_lattice_svg: output stream failed";
}
 
template <typename Lattice>
inline void render_lattice_svg(std::ostream &out,
                               const Lattice &frame,
                               const SVG_Render_Options &opts = {},
                               const typename Lattice::state_type &dead_state
                               = typename Lattice::state_type{})
{
  render_lattice_svg(out, frame, Binary_RGB_Mapper<typename Lattice::state_type>{}, opts,
                     dead_state);
}
 
template <typename Lattice, typename Palette>
[[nodiscard]] inline std::string render_lattice_svg_string(const Lattice &frame,
                                                           Palette &&palette,
                                                           const SVG_Render_Options &opts = {},
                                                           const typename Lattice::state_type
                                                             &dead_state
                                                           = typename Lattice::state_type{})
  requires requires(Palette &&p, const typename Lattice::state_type &v) {
    { p(v) } -> std::convertible_to<RGB8>;
  }
{
  std::ostringstream out;
  render_lattice_svg(out, frame, std::forward<Palette>(palette), opts, dead_state);
  return out.str();
}
 
template <typename Palette>
class Svg_Frame_Sink
{
  std::filesystem::path pattern_;
  Palette palette_;
  SVG_Render_Options opts_{};
  std::size_t zero_pad_ = 6;
 
public:
  Svg_Frame_Sink(std::filesystem::path path_pattern,
                 Palette palette,
                 SVG_Render_Options opts = {},
                 const std::size_t zero_pad = 6)
    : pattern_(std::move(path_pattern)), palette_(std::move(palette)), opts_(std::move(opts)),
      zero_pad_(zero_pad)
  {}
 
  template <typename Lattice>
  void accept(const std::size_t step, const Lattice &frame)
  {
    accept(step, frame, typename Lattice::state_type{});
  }
 
  template <typename Lattice>
  void accept(const std::size_t step,
              const Lattice &frame,
              const typename Lattice::state_type &dead_state)
  {
    const std::filesystem::path path = format_step_path(pattern_, step, zero_pad_);
    if (const auto parent = path.parent_path(); not parent.empty())
      std::filesystem::create_directories(parent);
    std::ofstream out(path);
    ah_runtime_error_if(not out) << "Svg_Frame_Sink::accept: cannot open '" << path.string() << "'";
    render_lattice_svg(out, frame, palette_, opts_, dead_state);
  }
 
  static void flush() {}
};
 
template <typename Palette>
Svg_Frame_Sink(std::filesystem::path, Palette, SVG_Render_Options = {}, std::size_t = 6)
  -> Svg_Frame_Sink<Palette>;
 
}  // namespace CA
}  // namespace Aleph
 
#endif  // CA_SVG_H