ft-text-renderer.cc

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2009-2022 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
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////////////////////////////////////////////////////////////////////////
 
#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif
 
#include "base-text-renderer.h"
#include "ft-text-renderer.h"
 
#if defined (HAVE_FREETYPE)
 
#if defined (HAVE_PRAGMA_GCC_DIAGNOSTIC)
#  pragma GCC diagnostic push
#  pragma GCC diagnostic ignored "-Wold-style-cast"
#endif
 
#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_GLYPH_H
 
#if defined (HAVE_FONTCONFIG)
#  include <fontconfig/fontconfig.h>
#endif
 
#if defined (HAVE_PRAGMA_GCC_DIAGNOSTIC)
#  pragma GCC diagnostic pop
#endif
 
#include <clocale>
#include <cwchar>
#include <map>
#include <utility>
 
#include "singleton-cleanup.h"
#include "unistr-wrappers.h"
 
#include "defaults.h"
#include "error.h"
#include "file-ops.h"
#include "oct-env.h"
#include "pr-output.h"
#include "sysdep.h"
#include "text-renderer.h"
 
namespace octave
{
  // FIXME: maybe issue at most one warning per glyph/font/size/weight
  //        combination.
 
  static void
  warn_missing_glyph (FT_ULong c)
  {
    warning_with_id ("Octave:missing-glyph",
                     "text_renderer: skipping missing glyph for character '%lx'", c);
  }
 
  static void
  warn_glyph_render (FT_ULong c)
  {
    warning_with_id ("Octave:glyph-render",
                     "text_renderer: unable to render glyph for character '%lx'", c);
  }
 
#if defined (_MSC_VER)
  // FIXME: is this really needed?
  //
  // This is just a trick to avoid multiple symbol definitions.
  // PermMatrix.h contains a dllexport'ed Array<octave_idx_type>
  // that will cause MSVC not to generate a new instantiation and
  // use the imported one instead.
#  include "PermMatrix.h"
#endif
 
  // Forward declaration
  static void ft_face_destroyed (void *object);
 
  class
  ft_manager
  {
  private:
 
    ft_manager (void)
      : m_library (), m_freetype_initialized (false),
        m_fontconfig_initialized (false)
    {
      if (FT_Init_FreeType (&m_library))
        error ("unable to initialize FreeType library");
      else
        m_freetype_initialized = true;
 
#if defined (HAVE_FONTCONFIG)
      if (! FcInit ())
        error ("unable to initialize fontconfig library");
      else
        m_fontconfig_initialized = true;
#endif
    }
 
  public:
 
    // No copying!
 
    ft_manager (const ft_manager&) = delete;
 
    ft_manager& operator = (const ft_manager&) = delete;
 
  private:
 
    ~ft_manager (void)
    {
      if (m_freetype_initialized)
        FT_Done_FreeType (m_library);
 
#if defined (HAVE_FONTCONFIG)
      // FIXME: Skip the call to FcFini because it can trigger the assertion
      //
      //   octave: fccache.c:507: FcCacheFini: Assertion 'fcCacheChains[i] == ((void *)0)' failed.
      //
      // if (m_fontconfig_initialized)
      //   FcFini ();
#endif
    }
 
  public:
 
    static bool instance_ok (void)
    {
      bool retval = true;
 
      if (! m_instance)
        {
          m_instance = new ft_manager ();
          singleton_cleanup_list::add (cleanup_instance);
        }
 
      return retval;
    }
 
    static void cleanup_instance (void)
    { delete m_instance; m_instance = nullptr; }
 
    static FT_Face get_font (const std::string& name, const std::string& weight,
                             const std::string& angle, double size,
                             FT_ULong c = 0)
    {
      return (instance_ok ()
              ? m_instance->do_get_font (name, weight, angle, size, c)
              : nullptr);
    }
 
    static octave_map get_system_fonts (void)
    {
      return (instance_ok ()
              ? m_instance->do_get_system_fonts ()
              : octave_map ());
    }
 
    static void font_destroyed (FT_Face face)
    {
      if (instance_ok ())
        m_instance->do_font_destroyed (face);
    }
 
  private:
 
    typedef std::pair<std::string, double> ft_key;
    typedef std::map<ft_key, FT_Face> ft_cache;
 
    static octave_map do_get_system_fonts (void)
    {
      static octave_map font_map;
 
      if (font_map.isempty ())
        {
#if defined (HAVE_FONTCONFIG)
          FcConfig *config = FcConfigGetCurrent();
          FcPattern *pat = FcPatternCreate ();
          FcObjectSet *os = FcObjectSetBuild (FC_FAMILY, FC_SLANT, FC_WEIGHT,
                                              FC_CHARSET, nullptr);
          FcFontSet *fs = FcFontList (config, pat, os);
 
          if (fs->nfont > 0)
            {
              // Mark fonts that have at least all printable ASCII chars
              FcCharSet *minimal_charset =  FcCharSetCreate ();
              for (int i = 32; i < 127; i++)
                FcCharSetAddChar (minimal_charset, static_cast<FcChar32> (i));
 
              string_vector fields (4);
              fields(0) = "family";
              fields(1) = "angle";
              fields(2) = "weight";
              fields(3) = "suitable";
 
              dim_vector dv (1, fs->nfont);
              Cell families (dv);
              Cell angles (dv);
              Cell weights (dv);
              Cell suitable (dv);
 
              unsigned char *family;
              int val;
              for (int i = 0; fs && i < fs->nfont; i++)
                {
                  FcPattern *font = fs->fonts[i];
                  if (FcPatternGetString (font, FC_FAMILY, 0, &family)
                      == FcResultMatch)
                    families(i) = std::string (reinterpret_cast<char *> (family));
                  else
                    families(i) = "unknown";
 
                  if (FcPatternGetInteger (font, FC_SLANT, 0, &val)
                      == FcResultMatch)
                    angles(i) = (val == FC_SLANT_ITALIC
                                 || val == FC_SLANT_OBLIQUE)
                                ? "italic" : "normal";
                  else
                    angles(i) = "unknown";
 
                  if (FcPatternGetInteger (font, FC_WEIGHT, 0, &val)
                      == FcResultMatch)
                    weights(i) = (val == FC_WEIGHT_BOLD
                                  || val == FC_WEIGHT_DEMIBOLD)
                                 ? "bold" : "normal";
                  else
                    weights(i) = "unknown";
 
                  FcCharSet *cset;
                  if (FcPatternGetCharSet (font, FC_CHARSET, 0, &cset)
                      == FcResultMatch)
                    suitable(i) = (FcCharSetIsSubset (minimal_charset, cset)
                                   ? true : false);
                  else
                    suitable(i) = false;
                }
 
              font_map = octave_map (dv, fields);
 
              font_map.assign ("family", families);
              font_map.assign ("angle", angles);
              font_map.assign ("weight", weights);
              font_map.assign ("suitable", suitable);
 
              if (fs)
                FcFontSetDestroy (fs);
            }
#endif
        }
 
      return font_map;
    }
 
    FT_Face do_get_font (const std::string& name, const std::string& weight,
                         const std::string& angle, double size,
                         FT_ULong search_code_point)
    {
      FT_Face retval = nullptr;
 
#if defined (HAVE_FT_REFERENCE_FACE)
      // Look first into the font cache, then use fontconfig.  If the font
      // is present in the cache, simply add a reference and return it.
 
      ft_key key (name + ':' + weight + ':' + angle + ':'
                  + std::to_string (search_code_point), size);
      ft_cache::const_iterator it = m_cache.find (key);
 
      if (it != m_cache.end ())
        {
          FT_Reference_Face (it->second);
          return it->second;
        }
#endif
 
      static std::string fonts_dir;
 
      if (fonts_dir.empty ())
        {
          fonts_dir = sys::env::getenv ("OCTAVE_FONTS_DIR");
 
          if (fonts_dir.empty ())
#if defined (SYSTEM_FREEFONT_DIR)
            fonts_dir = SYSTEM_FREEFONT_DIR;
#else
            fonts_dir = config::oct_fonts_dir ();
#endif
        }
 
 
      // Default font file
      std::string file;
 
      if (! fonts_dir.empty ())
        {
          file = fonts_dir + sys::file_ops::dir_sep_str () + "FreeSans";
 
          if (weight == "bold")
            file += "Bold";
 
          if (angle == "italic" || angle == "oblique")
            file += "Oblique";
 
          file += ".otf";
        }
 
#if defined (HAVE_FONTCONFIG)
      if ((search_code_point != 0 || name != "*") && m_fontconfig_initialized)
        {
          int fc_weight, fc_angle;
 
          if (weight == "bold")
            fc_weight = FC_WEIGHT_BOLD;
          else
            fc_weight = FC_WEIGHT_NORMAL;
 
          if (angle == "italic")
            fc_angle = FC_SLANT_ITALIC;
          else if (angle == "oblique")
            fc_angle = FC_SLANT_OBLIQUE;
          else
            fc_angle = FC_SLANT_ROMAN;
 
          FcPattern *pat = FcPatternCreate ();
 
          FcPatternAddString (pat, FC_FAMILY,
                              (reinterpret_cast<const FcChar8 *>
                               (name.c_str ())));
 
          FcPatternAddInteger (pat, FC_WEIGHT, fc_weight);
          FcPatternAddInteger (pat, FC_SLANT, fc_angle);
          FcPatternAddDouble (pat, FC_PIXEL_SIZE, size);
 
          if (search_code_point > 0)
            {
              FcCharSet *minimal_charset =  FcCharSetCreate ();
              FcCharSetAddChar (minimal_charset,
                                static_cast<FcChar32> (search_code_point));
              FcPatternAddCharSet (pat, FC_CHARSET, minimal_charset);
            }
 
          if (FcConfigSubstitute (nullptr, pat, FcMatchPattern))
            {
              FcResult res;
              FcPattern *match;
 
              FcDefaultSubstitute (pat);
 
              match = FcFontMatch (nullptr, pat, &res);
 
              // FIXME: originally, this test also required that
              // res != FcResultNoMatch.  Is that really needed?
              if (match)
                {
                  unsigned char *tmp;
 
                  FcPatternGetString (match, FC_FILE, 0, &tmp);
                  file = reinterpret_cast<char *> (tmp);
                }
              else
                ::warning ("could not match any font: %s-%s-%s-%g, using default font",
                           name.c_str (), weight.c_str (), angle.c_str (),
                           size);
 
              if (match)
                FcPatternDestroy (match);
            }
 
          FcPatternDestroy (pat);
        }
#endif
 
      if (file.empty ())
        ::warning ("unable to find default font files");
      else
        {
          std::string ascii_file = sys::get_ASCII_filename (file);
 
          if (FT_New_Face (m_library, ascii_file.c_str (), 0, &retval))
            ::warning ("ft_manager: unable to load font: %s", file.c_str ());
#if defined (HAVE_FT_REFERENCE_FACE)
          else
            {
              // Install a finalizer to notify ft_manager that the font is
              // being destroyed.  The class ft_manager only keeps weak
              // references to font objects.
 
              retval->generic.data = new ft_key (key);
              retval->generic.finalizer = ft_face_destroyed;
 
              // Insert loaded font into the cache.
              if (FT_Reference_Face (retval) == 0)
                m_cache[key] = retval;
            }
#endif
        }
 
      return retval;
    }
 
    void do_font_destroyed (FT_Face face)
    {
      if (face->generic.data)
        {
          ft_key *pkey = reinterpret_cast<ft_key *> (face->generic.data);
 
          m_cache.erase (*pkey);
          delete pkey;
          face->generic.data = nullptr;
          FT_Done_Face (face);
        }
    }
 
    //--------
 
    static ft_manager *m_instance;
 
    // Cache the fonts loaded by FreeType.  This cache only contains
    // weak references to the fonts, strong references are only present
    // in class text_renderer.
    ft_cache m_cache;
 
    FT_Library m_library;
    bool m_freetype_initialized;
    bool m_fontconfig_initialized;
  };
 
  ft_manager *ft_manager::m_instance = nullptr;
 
  static void
  ft_face_destroyed (void *object)
  {
    ft_manager::font_destroyed (reinterpret_cast<FT_Face> (object));
  }
 
  class
  OCTINTERP_API
  ft_text_renderer : public base_text_renderer
  {
  public:
 
    enum
    {
      MODE_BBOX   = 0,
      MODE_RENDER = 1
    };
 
  public:
 
    ft_text_renderer (void)
      : base_text_renderer (), m_font (), m_bbox (1, 4, 0.0), m_halign (0),
        m_xoffset (0), m_line_yoffset (0), m_yoffset (0), m_mode (MODE_BBOX),
        m_color (dim_vector (1, 3), 0), m_do_strlist (false), m_strlist (),
        m_line_xoffset (0), m_ymin (0), m_ymax (0), m_deltax (0),
        m_max_fontsize (0), m_antialias (true)
    { }
 
    // No copying!
 
    ft_text_renderer (const ft_text_renderer&) = delete;
 
    ft_text_renderer& operator = (const ft_text_renderer&) = delete;
 
    ~ft_text_renderer (void) = default;
 
    void visit (text_element_string& e);
 
    void visit (text_element_list& e);
 
    void visit (text_element_subscript& e);
 
    void visit (text_element_superscript& e);
 
    void visit (text_element_color& e);
 
    void visit (text_element_fontsize& e);
 
    void visit (text_element_fontname& e);
 
    void visit (text_element_fontstyle& e);
 
    void visit (text_element_symbol& e);
 
    void visit (text_element_combined& e);
 
    void reset (void);
 
    uint8NDArray get_pixels (void) const { return m_pixels; }
 
    Matrix get_boundingbox (void) const { return m_bbox; }
 
    uint8NDArray render (text_element *elt, Matrix& box,
                         int rotation = ROTATION_0);
 
    Matrix get_extent (text_element *elt, double rotation = 0.0);
    Matrix get_extent (const std::string& txt, double rotation,
                       const caseless_str& interpreter);
 
    void set_anti_aliasing (bool val) { m_antialias = val; };
 
    void set_font (const std::string& name, const std::string& weight,
                   const std::string& angle, double size);
 
    octave_map get_system_fonts (void);
 
    void set_color (const Matrix& c);
 
    void set_mode (int m);
 
    void text_to_pixels (const std::string& txt,
                         uint8NDArray& pxls, Matrix& bbox,
                         int halign, int valign, double rotation,
                         const caseless_str& interpreter,
                         bool handle_rotation);
 
  private:
 
    // Class to hold information about fonts and a strong
    // reference to the font objects loaded by FreeType.
 
    class ft_font : public text_renderer::font
    {
    public:
 
      ft_font (void)
        : text_renderer::font (), m_face (nullptr) { }
 
      ft_font (const std::string& nm, const std::string& wt,
               const std::string& ang, double sz, FT_Face f = nullptr)
        : text_renderer::font (nm, wt, ang, sz), m_face (f)
      { }
 
      ft_font (const ft_font& ft);
 
      ~ft_font (void)
      {
        if (m_face)
          FT_Done_Face (m_face);
      }
 
      ft_font& operator = (const ft_font& ft);
 
      bool is_valid (void) const { return get_face (); }
 
      FT_Face get_face (void) const;
 
    private:
 
      mutable FT_Face m_face;
    };
 
    void push_new_line (void);
 
    void update_line_bbox (void);
 
    void compute_bbox (void);
 
    int compute_line_xoffset (const Matrix& lb) const;
 
    FT_UInt process_character (FT_ULong code, FT_UInt previous,
                               std::string& sub_font);
 
  public:
 
    void text_to_strlist (const std::string& txt,
                          std::list<text_renderer::string>& lst, Matrix& bbox,
                          int halign, int valign, double rotation,
                          const caseless_str& interp);
 
  private:
 
    // The current font used by the renderer.
    ft_font m_font;
 
    // Used to stored the bounding box corresponding to the rendered text.
    // The bounding box has the form [x, y, w, h] where x and y represent the
    // coordinates of the bottom left corner relative to the anchor point of
    // the text (== start of text on the baseline).  Due to font descent or
    // multiple lines, the value y is usually negative.
    Matrix m_bbox;
 
    // Used to stored the rendered text.  It's a 3D matrix with size MxNx4
    // where M and N are the width and height of the bounding box.
    uint8NDArray m_pixels;
 
    // Used to store the bounding box of each line.  This is used to layout
    // multiline text properly.
    std::list<Matrix> m_line_bbox;
 
    // The current horizontal alignment.  This is used to align multi-line text.
    int m_halign;
 
    // The X offset for the next glyph.
    int m_xoffset;
 
    // The Y offset of the baseline for the current line.
    int m_line_yoffset;
 
    // The Y offset of the baseline for the next glyph.  The offset is relative
    // to line_yoffset.  The total Y offset is computed with:
    // line_yoffset + yoffset.
    int m_yoffset;
 
    // The current mode of the rendering process (box computing or rendering).
    int m_mode;
 
    // The base color of the rendered text.
    uint8NDArray m_color;
 
    // A list of parsed strings to be used for printing.
    bool m_do_strlist;
    std::list<text_renderer::string> m_strlist;
 
    // The X offset of the baseline for the current line.
    int m_line_xoffset;
 
    // Min and max y coordinates of all glyphs in a line.
    FT_Pos m_ymin;
    FT_Pos m_ymax;
 
    // Difference between the advance and the actual extent of the latest glyph
    FT_Pos m_deltax;
 
    // Used for computing the distance between lines.
    double m_max_fontsize;
 
    // Anti-aliasing.
    bool m_antialias;
 
  };
 
  void
  ft_text_renderer::set_font (const std::string& name,
                              const std::string& weight,
                              const std::string& angle, double size)
  {
    // FIXME: take "fontunits" into account
    m_font = ft_font (name, weight, angle, size, nullptr);
  }
 
  octave_map
  ft_text_renderer::get_system_fonts (void)
  {
    return ft_manager::get_system_fonts ();
  }
 
  void
  ft_text_renderer::push_new_line (void)
  {
    switch (m_mode)
      {
      case MODE_BBOX:
        {
          // Create a new bbox entry based on the current font.
 
          FT_Face face = m_font.get_face ();
 
          if (face)
            {
              Matrix bb (1, 5, 0.0);
 
              m_line_bbox.push_back (bb);
 
              m_xoffset = m_yoffset = 0;
              m_ymin = m_ymax = m_deltax = 0;
            }
        }
        break;
 
      case MODE_RENDER:
        {
          // Move to the next line bbox, adjust xoffset based on alignment
          // and yoffset based on the old and new line bbox.
 
          Matrix old_bbox = m_line_bbox.front ();
          m_line_bbox.pop_front ();
          Matrix new_bbox = m_line_bbox.front ();
 
          m_xoffset = m_line_xoffset = compute_line_xoffset (new_bbox);
          m_line_yoffset -= (-old_bbox(1) + math::round (0.4 * m_max_fontsize)
                             + (new_bbox(3) + new_bbox(1)));
          m_yoffset = 0;
          m_ymin = m_ymax = m_deltax = 0;
        }
        break;
      }
  }
 
  int
  ft_text_renderer::compute_line_xoffset (const Matrix& lb) const
  {
    if (! m_bbox.isempty ())
      {
        switch (m_halign)
          {
          case 0:
            return 0;
          case 1:
            return (m_bbox(2) - lb(2)) / 2;
          case 2:
            return (m_bbox(2) - lb(2));
          }
      }
 
    return 0;
  }
 
  void
  ft_text_renderer::compute_bbox (void)
  {
    // Stack the various line bbox together and compute the final
    // bounding box for the entire text string.
 
    m_bbox = Matrix ();
 
    switch (m_line_bbox.size ())
      {
      case 0:
        break;
 
      case 1:
        m_bbox = m_line_bbox.front ().extract (0, 0, 0, 3);
        break;
 
      default:
        for (const auto& lbox : m_line_bbox)
          {
            if (m_bbox.isempty ())
              m_bbox = lbox.extract (0, 0, 0, 3);
            else
              {
                double delta = math::round (0.4 * m_max_fontsize) + lbox(3);
                m_bbox(1) -= delta;
                m_bbox(3) += delta;
                m_bbox(2) = math::max (m_bbox(2), lbox(2));
              }
          }
        break;
      }
  }
 
  void
  ft_text_renderer::update_line_bbox (void)
  {
    // Called after a font change, when in MODE_BBOX mode, to update the
    // current line bbox with the new font metrics.  This also includes the
    // current yoffset, that is the offset of the current glyph's baseline
    // the line's baseline.
 
    if (m_mode == MODE_BBOX)
      {
        Matrix& bb = m_line_bbox.back ();
        bb(1) = m_ymin;
        // Add one pixel to the bbox height to avoid occasional text clipping.
        // See bug #55328.
        bb(3) = (m_ymax + 1) - m_ymin;
        if (m_deltax > 0)
          bb(2) += m_deltax;
      }
  }
 
  void
  ft_text_renderer::set_mode (int m)
  {
    m_mode = m;
 
    switch (m_mode)
      {
      case MODE_BBOX:
        m_xoffset = m_line_yoffset = m_yoffset = 0;
        m_max_fontsize = 0.0;
        m_bbox = Matrix (1, 4, 0.0);
        m_line_bbox.clear ();
        push_new_line ();
        break;
 
      case MODE_RENDER:
        if (m_bbox.numel () != 4)
          {
            ::error ("ft_text_renderer: invalid bounding box, cannot render");
 
            m_xoffset = m_line_yoffset = m_yoffset = 0;
            m_pixels = uint8NDArray ();
          }
        else
          {
            dim_vector d (4, octave_idx_type (m_bbox(2)),
                          octave_idx_type (m_bbox(3)));
            m_pixels = uint8NDArray (d, static_cast<uint8_t> (0));
            m_xoffset = compute_line_xoffset (m_line_bbox.front ());
            m_line_yoffset = -m_bbox(1);
            m_yoffset = 0;
          }
        break;
 
      default:
        error ("ft_text_renderer: invalid mode '%d'", m_mode);
        break;
      }
  }
 
  bool is_opaque (const FT_GlyphSlot& glyph, const int x, const int y)
  {
    // Borrowed from https://stackoverflow.com/questions/14800827/
    //    indexing-pixels-in-a-monochrome-freetype-glyph-buffer
    int pitch = std::abs (glyph->bitmap.pitch);
    unsigned char *row = &glyph->bitmap.buffer[pitch * y];
    char cvalue = row[x >> 3];
 
    return ((cvalue & (128 >> (x & 7))) != 0);
  }
 
  FT_UInt
  ft_text_renderer::process_character (FT_ULong code, FT_UInt previous,
                                       std::string& sub_name)
  {
    FT_Face face = m_font.get_face ();
 
    sub_name = face->family_name;
 
    FT_UInt glyph_index = 0;
 
    if (face)
      {
        glyph_index = FT_Get_Char_Index (face, code);
 
        if (code != '\n' && code != '\t'
            && (! glyph_index
                || FT_Load_Glyph (face, glyph_index, FT_LOAD_DEFAULT)))
          {
#if defined (HAVE_FONTCONFIG)
            // Try to substitue font
            FT_Face sub_face = ft_manager::get_font (m_font.get_name (),
                                                     m_font.get_weight (),
                                                     m_font.get_angle (),
                                                     m_font.get_size (),
                                                     code);
 
            if (sub_face)
              {
                FT_Set_Char_Size (sub_face, 0, m_font.get_size ()*64, 0, 0);
 
                glyph_index = FT_Get_Char_Index (sub_face, code);
 
                if (glyph_index
                    && (FT_Load_Glyph (sub_face, glyph_index, FT_LOAD_DEFAULT)
                        == 0))
                  {
                    static std::string prev_sub_name;
 
                    if (prev_sub_name.empty ()
                        || prev_sub_name != std::string (sub_face->family_name))
                      {
                        prev_sub_name = sub_face->family_name;
                        warning_with_id ("Octave:substituted-glyph",
                                         "text_renderer: substituting font to '%s' for some characters",
                                         sub_face->family_name);
                      }
 
                    ft_font saved_font = m_font;
 
                    m_font = ft_font (m_font.get_name (), m_font.get_weight (),
                                      m_font.get_angle (), m_font.get_size (),
                                      sub_face);
 
                    process_character (code, previous, sub_name);
 
                    m_font = saved_font;
                  }
                else
                  {
                    glyph_index = 0;
                    warn_missing_glyph (code);
                  }
              }
            else
              {
                glyph_index = 0;
                warn_missing_glyph (code);
              }
#else
            glyph_index = 0;
            warn_missing_glyph (code);
#endif
          }
        else if ((code == '\n') || (code == '\t'))
          {
            glyph_index = FT_Get_Char_Index (face, ' ');
            if (! glyph_index
                || FT_Load_Glyph (face, glyph_index, FT_LOAD_DEFAULT))
              {
                glyph_index = 0;
                warn_missing_glyph (' ');
              }
            else if (code == '\n')
              push_new_line ();
            else
              {
                // Advance to next multiple of 4 times the width of the "space"
                // character.
                int x_tab = 4 * (face->glyph->advance.x >> 6);
                m_xoffset = (1 + std::floor (1. * m_xoffset / x_tab)) * x_tab;
              }
          }
        else
          {
            switch (m_mode)
              {
              case MODE_RENDER:
                if (FT_Render_Glyph (face->glyph, (m_antialias
                                                   ? FT_RENDER_MODE_NORMAL
                                                   : FT_RENDER_MODE_MONO)))
                  {
                    glyph_index = 0;
                    warn_glyph_render (code);
                  }
                else
                  {
                    FT_Bitmap& bitmap = face->glyph->bitmap;
                    int x0, y0;
 
                    if (previous)
                      {
                        FT_Vector delta;
 
                        FT_Get_Kerning (face, previous, glyph_index,
                                        FT_KERNING_DEFAULT, &delta);
 
                        m_xoffset += (delta.x >> 6);
                      }
 
                    x0 = m_xoffset + face->glyph->bitmap_left;
                    y0 = m_line_yoffset + m_yoffset
                         + (face->glyph->bitmap_top - 1);
 
                    // 'w' seems to have a negative -1
                    // face->glyph->bitmap_left, this is so we don't index out
                    // of bound, and assumes we've allocated the right amount of
                    // horizontal space in the bbox.
                    if (x0 < 0)
                      x0 = 0;
 
                    for (int r = 0; static_cast<unsigned int> (r) < bitmap.rows; r++)
                      for (int c = 0; static_cast<unsigned int> (c) < bitmap.width; c++)
                        {
                          unsigned char pix
                            = (m_antialias
                               ? bitmap.buffer[r*bitmap.width+c]
                               : (is_opaque (face->glyph, c, r) ? 255 : 0));
 
                          if (x0+c < 0 || x0+c >= m_pixels.dim2 ()
                              || y0-r < 0 || y0-r >= m_pixels.dim3 ())
                            {
                              // ::warning ("ft_text_renderer: x %d,  y %d",
                              //            x0+c, y0-r);
                            }
                          else if (m_pixels(3, x0+c, y0-r).value () == 0)
                            {
                              m_pixels(0, x0+c, y0-r) = m_color(0);
                              m_pixels(1, x0+c, y0-r) = m_color(1);
                              m_pixels(2, x0+c, y0-r) = m_color(2);
                              m_pixels(3, x0+c, y0-r) = pix;
                            }
                        }
 
                    m_xoffset += (face->glyph->advance.x >> 6);
                  }
                break;
 
              case MODE_BBOX:
                Matrix& bb = m_line_bbox.back ();
 
                // If we have a previous glyph, use kerning information.  This
                // usually means moving a bit backward before adding the next
                // glyph.  That is, "delta.x" is usually < 0.
                if (previous)
                  {
                    FT_Vector delta;
 
                    FT_Get_Kerning (face, previous, glyph_index,
                                    FT_KERNING_DEFAULT, &delta);
 
                    m_xoffset += (delta.x >> 6);
                  }
 
                // Extend current X offset box by the width of the current
                // glyph.  Then extend the line bounding box if necessary.
 
                m_xoffset += (face->glyph->advance.x >> 6);
                bb(2) = math::max (bb(2), m_xoffset);
 
                // Store the actual bbox vertical coordinates of this character
                FT_Glyph glyph;
                if (FT_Get_Glyph (face->glyph, &glyph))
                  warn_glyph_render (code);
                else
                  {
                    FT_BBox  glyph_bbox;
                    FT_Glyph_Get_CBox (glyph, FT_GLYPH_BBOX_UNSCALED,
                                       &glyph_bbox);
                    m_deltax = (glyph_bbox.xMax - face->glyph->advance.x) >> 6;
                    m_ymin = math::min ((glyph_bbox.yMin >> 6) + m_yoffset,
                                        m_ymin);
                    m_ymax = math::max ((glyph_bbox.yMax >> 6) + m_yoffset,
                                        m_ymax);
                    FT_Done_Glyph (glyph);
                    update_line_bbox ();
                  }
                break;
              }
          }
      }
 
    return glyph_index;
  }
 
  void
  ft_text_renderer::text_to_strlist (const std::string& txt,
                                     std::list<text_renderer::string>& lst,
                                     Matrix& box,
                                     int ha, int va, double rot,
                                     const caseless_str& interp)
  {
    uint8NDArray pxls;
 
    // First run text_to_pixels which will also build the string list
 
    m_strlist = std::list<text_renderer::string> ();
 
    unwind_protect_var<bool> restore_var1 (m_do_strlist);
    unwind_protect_var<std::list<text_renderer::string>>
      restore_var2 (m_strlist);
 
    m_do_strlist = true;
 
    text_to_pixels (txt, pxls, box, ha, va, rot, interp, false);
 
    lst = m_strlist;
  }
 
  void
  ft_text_renderer::visit (text_element_string& e)
  {
    if (m_font.is_valid ())
      {
        m_max_fontsize = std::max (m_max_fontsize, m_font.get_size ());
        FT_UInt glyph_index, previous = 0;
 
        std::string str = e.string_value ();
        const uint8_t *c = reinterpret_cast<const uint8_t *> (str.c_str ());
        uint32_t u32_c;
 
        std::size_t n = str.size ();
        std::size_t icurr = 0;
        std::size_t ibegin = 0;
 
        // Initialize a new string
        text_renderer::string fs (str, m_font, m_xoffset, m_yoffset);
 
        std::string fname = m_font.get_face ()->family_name;
 
        if (fname.find (" ") != std::string::npos)
          fname = "'" + fname + "'";
 
        fs.set_family (fname);
 
        std::vector<double> xdata;
        std::string sub_name;
 
        while (n > 0)
          {
            // Retrieve the length and the u32 representation of the current
            // character
            int mblen = octave_u8_strmbtouc_wrapper (&u32_c, c + icurr);
            if (mblen < 1)
              {
                // This is not an UTF-8 character, use a replacement character
                mblen = 1;
                u32_c = 0xFFFD;
              }
 
            n -= mblen;
 
            if (m_do_strlist && m_mode == MODE_RENDER)
              {
                if (u32_c == 10)
                  {
                    // Finish previous string in m_strlist before processing
                    // the newline character
                    fs.set_y (m_line_yoffset + m_yoffset);
                    fs.set_color (m_color);
 
                    std::string s = str.substr (ibegin, icurr - ibegin);
                    if (! s.empty ())
                      {
                        fs.set_string (s);
                        fs.set_y (m_line_yoffset + m_yoffset);
                        fs.set_xdata (xdata);
                        fs.set_family (fname);
                        m_strlist.push_back (fs);
                      }
                  }
                else
                  xdata.push_back (m_xoffset);
              }
 
            glyph_index = process_character (u32_c, previous, sub_name);
 
            if (m_do_strlist && m_mode == MODE_RENDER && ! sub_name.empty ())
              {
                // Add substitution font to the family name stack
                std::string tmp_family = fs.get_family ();
 
                if (tmp_family.find (sub_name) == std::string::npos)
                  {
                    if (sub_name.find (" ") != std::string::npos)
                      sub_name = "'" + sub_name + "'";
 
                    fs.set_family (tmp_family + ", " + sub_name);
                  }
              }
 
            if (u32_c == 10)
              {
                previous = 0;
 
                if (m_do_strlist && m_mode == MODE_RENDER)
                  {
                    // Start a new string in m_strlist
                    ibegin = icurr+1;
                    xdata.clear ();
                    fs = text_renderer::string (str.substr (ibegin), m_font,
                                                m_line_xoffset, m_yoffset);
                  }
              }
            else
              previous = glyph_index;
 
            icurr += mblen;
          }
 
        if (m_do_strlist && m_mode == MODE_RENDER
            && ! fs.get_string ().empty ())
          {
            fs.set_y (m_line_yoffset + m_yoffset);
            fs.set_color (m_color);
            fs.set_xdata (xdata);
            m_strlist.push_back (fs);
          }
      }
  }
 
  void
  ft_text_renderer::visit (text_element_list& e)
  {
    // Save and restore (after processing the list) the current font and color.
 
    ft_font saved_font (m_font);
    uint8NDArray saved_color (m_color);
 
    text_processor::visit (e);
 
    m_font = saved_font;
    m_color = saved_color;
  }
 
  void
  ft_text_renderer::visit (text_element_subscript& e)
  {
    ft_font saved_font (m_font);
    int saved_line_yoffset = m_line_yoffset;
    int saved_yoffset = m_yoffset;
 
    double sz = m_font.get_size ();
 
    // Reducing font size by 70% produces decent results.
    set_font (m_font.get_name (), m_font.get_weight (), m_font.get_angle (),
              std::max (5.0, sz * 0.7));
 
    if (m_font.is_valid ())
      {
        // Shifting the baseline by 15% of the font size gives decent results.
        m_yoffset -= std::ceil (sz * 0.15);
 
        if (m_mode == MODE_BBOX)
          update_line_bbox ();
      }
 
    text_processor::visit (e);
 
    m_font = saved_font;
    // If line_yoffset changed, this means we moved to a new line; hence yoffset
    // cannot be restored, because the saved value is not relevant anymore.
    if (m_line_yoffset == saved_line_yoffset)
      m_yoffset = saved_yoffset;
  }
 
  void
  ft_text_renderer::visit (text_element_superscript& e)
  {
    ft_font saved_font (m_font);
    int saved_line_yoffset = m_line_yoffset;
    int saved_yoffset = m_yoffset;
 
    double sz = m_font.get_size ();
 
    // Reducing font size by 70% produces decent results.
    set_font (m_font.get_name (), m_font.get_weight (), m_font.get_angle (),
              std::max (5.0, sz * 0.7));
 
    if (saved_font.is_valid ())
      {
        // Shifting the baseline by 40% of the font size gives decent results.
        m_yoffset += std::ceil (sz * 0.4);
 
        if (m_mode == MODE_BBOX)
          update_line_bbox ();
      }
 
    text_processor::visit (e);
 
    m_font = saved_font;
    // If line_yoffset changed, this means we moved to a new line; hence yoffset
    // cannot be restored, because the saved value is not relevant anymore.
    if (m_line_yoffset == saved_line_yoffset)
      m_yoffset = saved_yoffset;
  }
 
  void
  ft_text_renderer::visit (text_element_color& e)
  {
    if (m_mode == MODE_RENDER)
      set_color (e.get_color ());
  }
 
  void
  ft_text_renderer::visit (text_element_fontsize& e)
  {
    double sz = e.get_fontsize ();
 
    // FIXME: Matlab documentation says that the font size is expressed
    //        in the text object FontUnit.
 
    set_font (m_font.get_name (), m_font.get_weight (),
              m_font.get_angle (), sz);
 
    if (m_mode == MODE_BBOX)
      update_line_bbox ();
  }
 
  void
  ft_text_renderer::visit (text_element_fontname& e)
  {
    set_font (e.get_fontname (), m_font.get_weight (), m_font.get_angle (),
              m_font.get_size ());
 
    if (m_mode == MODE_BBOX)
      update_line_bbox ();
  }
 
  void
  ft_text_renderer::visit (text_element_fontstyle& e)
  {
    switch (e.get_fontstyle ())
      {
      case text_element_fontstyle::normal:
        set_font (m_font.get_name (), "normal", "normal", m_font.get_size ());
        break;
 
      case text_element_fontstyle::bold:
        set_font (m_font.get_name (), "bold", "normal", m_font.get_size ());
        break;
 
      case text_element_fontstyle::italic:
        set_font (m_font.get_name (), "normal", "italic", m_font.get_size ());
        break;
 
      case text_element_fontstyle::oblique:
        set_font (m_font.get_name (), "normal", "oblique", m_font.get_size ());
        break;
      }
 
    if (m_mode == MODE_BBOX)
      update_line_bbox ();
  }
 
  void
  ft_text_renderer::visit (text_element_symbol& e)
  {
    uint32_t code = e.get_symbol_code ();
 
    std::vector<double> xdata (1, m_xoffset);
    text_renderer::string fs ("-", m_font, m_xoffset, m_yoffset);
 
    if (code != text_element_symbol::invalid_code && m_font.is_valid ())
      {
        std::string sub_name;
 
        process_character (code, 0, sub_name);
 
        if (m_do_strlist && m_mode == MODE_RENDER)
          {
            if (! sub_name.empty ())
              {
                // Add substitution font to the family name
                std::string tmp_family = fs.get_family ();
 
                if (tmp_family.find (sub_name) == std::string::npos)
                  {
                    if (sub_name.find (" ") != std::string::npos)
                      sub_name = "'" + sub_name + "'";
 
                    fs.set_family (tmp_family + ", " + sub_name);
                  }
              }
 
            fs.set_code (code);
            fs.set_xdata (xdata);
          }
      }
    else if (m_font.is_valid ())
      ::warning ("ignoring unknown symbol: %d", e.get_symbol ());
 
    if (m_do_strlist && m_mode == MODE_RENDER && fs.get_code ())
      {
        fs.set_y (m_line_yoffset + m_yoffset);
        fs.set_color (m_color);
        fs.set_family (m_font.get_face ()->family_name);
        m_strlist.push_back (fs);
      }
  }
 
  void
  ft_text_renderer::visit (text_element_combined& e)
  {
    int saved_xoffset = m_xoffset;
    int max_xoffset = m_xoffset;
 
    for (auto *txt_elt : e)
      {
        m_xoffset = saved_xoffset;
        txt_elt->accept (*this);
        max_xoffset = math::max (m_xoffset, max_xoffset);
      }
 
    m_xoffset = max_xoffset;
  }
 
  void
  ft_text_renderer::reset (void)
  {
    set_mode (MODE_BBOX);
    set_color (Matrix (1, 3, 0.0));
    m_strlist = std::list<text_renderer::string> ();
  }
 
  void
  ft_text_renderer::set_color (const Matrix& c)
  {
    if (c.numel () == 3)
      {
        m_color(0) = static_cast<uint8_t> (c(0)*255);
        m_color(1) = static_cast<uint8_t> (c(1)*255);
        m_color(2) = static_cast<uint8_t> (c(2)*255);
      }
    else
      ::warning ("ft_text_renderer::set_color: invalid color");
  }
 
  uint8NDArray
  ft_text_renderer::render (text_element *elt, Matrix& box, int rotation)
  {
    set_mode (MODE_BBOX);
    elt->accept (*this);
    compute_bbox ();
    box = m_bbox;
 
    set_mode (MODE_RENDER);
 
    if (m_pixels.numel () > 0)
      {
        elt->accept (*this);
 
        rotate_pixels (m_pixels, rotation);
      }
 
    return m_pixels;
  }
 
  // Note:
  // x-extent accurately measures width of glyphs.
  // y-extent is overly large because it is measured from baseline-to-baseline.
  // Calling routines, such as ylabel, may need to account for this mismatch.
 
  Matrix
  ft_text_renderer::get_extent (text_element *elt, double rotation)
  {
    set_mode (MODE_BBOX);
    elt->accept (*this);
    compute_bbox ();
 
    Matrix extent (1, 2, 0.0);
 
    switch (rotation_to_mode (rotation))
      {
      case ROTATION_0:
      case ROTATION_180:
        extent(0) = m_bbox(2);
        extent(1) = m_bbox(3);
        break;
 
      case ROTATION_90:
      case ROTATION_270:
        extent(0) = m_bbox(3);
        extent(1) = m_bbox(2);
      }
 
    return extent;
  }
 
  Matrix
  ft_text_renderer::get_extent (const std::string& txt, double rotation,
                                const caseless_str& interpreter)
  {
    text_element *elt = text_parser::parse (txt, interpreter);
    Matrix extent = get_extent (elt, rotation);
    delete elt;
 
    return extent;
  }
 
  void
  ft_text_renderer::text_to_pixels (const std::string& txt,
                                    uint8NDArray& pxls, Matrix& box,
                                    int _halign, int valign, double rotation,
                                    const caseless_str& interpreter,
                                    bool handle_rotation)
  {
    int rot_mode = rotation_to_mode (rotation);
 
    m_halign = _halign;
 
    text_element *elt = text_parser::parse (txt, interpreter);
    pxls = render (elt, box, rot_mode);
    delete elt;
 
    if (pxls.isempty ())
      return;  // nothing to render
 
    // Move X0 and Y0 depending on alignments and eventually swap all values
    // for text rotated 90° 180° or 270°
    fix_bbox_anchor (box, m_halign, valign, rot_mode, handle_rotation);
  }
 
  ft_text_renderer::ft_font::ft_font (const ft_font& ft)
    : text_renderer::font (ft), m_face (nullptr)
  {
#if defined (HAVE_FT_REFERENCE_FACE)
    FT_Face ft_face = ft.get_face ();
 
    if (ft_face && FT_Reference_Face (ft_face) == 0)
      m_face = ft_face;
#endif
  }
 
  ft_text_renderer::ft_font&
  ft_text_renderer::ft_font::operator = (const ft_font& ft)
  {
    if (&ft != this)
      {
        text_renderer::font::operator = (ft);
 
        if (m_face)
          {
            FT_Done_Face (m_face);
            m_face = nullptr;
          }
 
#if defined (HAVE_FT_REFERENCE_FACE)
        FT_Face ft_face = ft.get_face ();
 
        if (ft_face && FT_Reference_Face (ft_face) == 0)
          m_face = ft_face;
#endif
      }
 
    return *this;
  }
 
  FT_Face
  ft_text_renderer::ft_font::get_face (void) const
  {
    if (! m_face && ! m_name.empty ())
      {
        m_face = ft_manager::get_font (m_name, m_weight, m_angle, m_size);
 
        if (m_face)
          {
            if (FT_Set_Char_Size (m_face, 0, m_size*64, 0, 0))
              ::warning ("ft_text_renderer: unable to set font size to %g", m_size);
          }
        else
          ::warning ("ft_text_renderer: unable to load appropriate font");
      }
 
    return m_face;
  }
}
 
#endif
 
namespace octave
{
  base_text_renderer *
  make_ft_text_renderer (void)
  {
#if defined (HAVE_FREETYPE)
    return new ft_text_renderer ();
#else
    return 0;
#endif
  }
}