xref: /dports/science/rdkit/rdkit-Release_2021_03_5/Code/GraphMol/MolDraw2D/DrawText.cpp

//
//   @@ All Rights Reserved @@
//  This file is part of the RDKit.
//  The contents are covered by the terms of the BSD license
//  which is included in the file license.txt, found at the root
//  of the RDKit source tree.
//
// Original author: David Cosgrove (CozChemIx) on 29/04/2020.
//

#include <GraphMol/MolDraw2D/DrawText.h>

namespace RDKit {

// ****************************************************************************
DrawText::DrawText(double max_fnt_sz, double min_fnt_sz)
    : colour_(DrawColour(0.0, 0.0, 0.0)),
      font_scale_(1.0),
      max_font_size_(max_fnt_sz),
      min_font_size_(min_fnt_sz) {}

// ****************************************************************************
DrawColour const &DrawText::colour() const { return colour_; }

// ****************************************************************************
void DrawText::setColour(const DrawColour &col) { colour_ = col; }

// ****************************************************************************
double DrawText::fontSize() const { return fontScale() * baseFontSize(); }

// ****************************************************************************
void DrawText::setFontSize(double new_size) {
  if (new_size < minFontSize()) {
    BOOST_LOG(rdWarningLog)
        << "The new font size " << new_size << " is below the current minimum ("
        << minFontSize() << ")." << std::endl;
  } else if (new_size > maxFontSize()) {
    BOOST_LOG(rdWarningLog)
        << "The new font size " << new_size << " is above the current maximum ("
        << maxFontSize() << ")." << std::endl;
  }
  double new_scale = new_size / baseFontSize();
  setFontScale(new_scale);
}

// ****************************************************************************
double DrawText::baseFontSize() const { return base_font_size_; }
// ****************************************************************************
void DrawText::setBaseFontSize(double val) { base_font_size_ = val; }

// ****************************************************************************
double DrawText::maxFontSize() const { return max_font_size_; }

// ****************************************************************************
void DrawText::setMaxFontSize(double new_max) { max_font_size_ = new_max; }

// ****************************************************************************
double DrawText::minFontSize() const { return min_font_size_; }

// ****************************************************************************
void DrawText::setMinFontSize(double new_min) { min_font_size_ = new_min; }

// ****************************************************************************
double DrawText::fontScale() const { return font_scale_; }

// ****************************************************************************
void DrawText::setFontScale(double new_scale) {
  font_scale_ = new_scale;
  double nfs = fontSize();
  if (max_font_size_ != -1 &&
      nfs * (baseFontSize() / FONT_SIZE) > max_font_size_) {
    font_scale_ = max_font_size_ / baseFontSize();
  }
  if (min_font_size_ != -1 &&
      nfs * (baseFontSize() / FONT_SIZE) < min_font_size_) {
    font_scale_ = min_font_size_ / baseFontSize();
  }
}

// ****************************************************************************
void DrawText::drawString(const std::string &str, const Point2D &cds,
                          TextAlignType talign) {
  std::vector<std::shared_ptr<StringRect>> rects;
  std::vector<TextDrawType> draw_modes;
  std::vector<char> draw_chars;
  getStringRects(str, rects, draw_modes, draw_chars);
  alignString(talign, draw_modes, rects);
  drawChars(cds, rects, draw_modes, draw_chars);
}

// ****************************************************************************
void DrawText::drawString(const std::string &label, const Point2D &cds,
                          OrientType orient) {
  std::vector<std::shared_ptr<StringRect>> rects;
  std::vector<TextDrawType> draw_modes;
  std::vector<char> draw_chars;
  getStringRects(label, orient, rects, draw_modes, draw_chars);
  drawChars(cds, rects, draw_modes, draw_chars);
}

// ****************************************************************************
void DrawText::adjustLineForString(const std::string &label, OrientType orient,
                                   const Point2D &end1, Point2D &end2) const {
  std::vector<std::shared_ptr<StringRect>> rects;
  std::vector<TextDrawType> draw_modes;
  std::vector<char> draw_chars;
  Point2D lab_pos = end2;

  getStringRects(label, orient, rects, draw_modes, draw_chars);
  double bond_len = (end1 - end2).length();
  for (size_t i = 0; i < rects.size(); ++i) {
    const auto &r = rects[i];
    r->trans_ += lab_pos;

    Point2D tl, tr, bl, br;
    r->calcCorners(tl, tr, br, bl, 0.025 * bond_len);
    std::unique_ptr<Point2D> ip(new Point2D);

    // if it's a wide label, such as C:7, the bond can intersect
    // more than 1 side of the rectangle, so check them all.
    if (doLinesIntersect(end2, end1, tl, tr, ip.get())) {
      end2 = *ip;
    }
    if (doLinesIntersect(end2, end1, tr, br, ip.get())) {
      end2 = *ip;
    }
    if (doLinesIntersect(end2, end1, br, bl, ip.get())) {
      end2 = *ip;
    }
    if (doLinesIntersect(end2, end1, bl, tl, ip.get())) {
      end2 = *ip;
    }
  }
}

// ****************************************************************************
void DrawText::drawStringRects(const std::string &label, OrientType orient,
                               const Point2D &cds, MolDraw2D &mol_draw) const {
  std::vector<std::shared_ptr<StringRect>> rects;
  std::vector<TextDrawType> draw_modes;
  std::vector<char> draw_chars;

  size_t i = 0;
  getStringRects(label, orient, rects, draw_modes, draw_chars);
  for (auto r : rects) {
    r->trans_.x += cds.x;
    r->trans_.y += cds.y;
    Point2D tl, tr, br, bl;
    r->calcCorners(tl, tr, br, bl, 0.0);

    tl = mol_draw.getAtomCoords(std::make_pair(tl.x, tl.y));
    tr = mol_draw.getAtomCoords(std::make_pair(tr.x, tr.y));
    br = mol_draw.getAtomCoords(std::make_pair(br.x, br.y));
    bl = mol_draw.getAtomCoords(std::make_pair(bl.x, bl.y));

    mol_draw.setColour(DrawColour(1.0, 0.0, 0.0));
    mol_draw.drawLine(tl, tr);
    mol_draw.setColour(DrawColour(0.0, 1.0, 0.0));
    mol_draw.drawLine(tr, br);
    mol_draw.setColour(DrawColour(0.0, 0.0, 1.0));
    mol_draw.drawLine(br, bl);
    mol_draw.setColour(DrawColour(0.0, 0.95, 0.95));
    mol_draw.drawLine(bl, tl);
    ++i;
  }
}

// ****************************************************************************
bool DrawText::doesRectIntersect(const std::string &label, OrientType orient,
                                 const Point2D &cds,
                                 const StringRect &rect) const {
  if (label.empty()) {
    return false;
  }
  std::vector<std::shared_ptr<StringRect>> rects;
  std::vector<TextDrawType> draw_modes;
  std::vector<char> draw_chars;

  getStringRects(label, orient, rects, draw_modes, draw_chars);
  return doesRectIntersect(rects, cds, rect);
}

// ****************************************************************************
bool DrawText::doesRectIntersect(
    const std::vector<std::shared_ptr<StringRect>> &rects, const Point2D &cds,
    const StringRect &rect) const {
  for (auto r : rects) {
    StringRect nr(*r);
    nr.trans_ += cds;
    if (nr.doesItIntersect(rect)) {
      return true;
    }
  }

  return false;
}

// ****************************************************************************
bool DrawText::doesLineIntersect(const std::string &label, OrientType orient,
                                 const Point2D &cds, const Point2D &end1,
                                 const Point2D &end2, double padding) const {
  std::vector<std::shared_ptr<StringRect>> rects;
  std::vector<TextDrawType> draw_modes;
  std::vector<char> draw_chars;

  getStringRects(label, orient, rects, draw_modes, draw_chars);
  return doesLineIntersect(rects, cds, end1, end2, padding);
}

// ****************************************************************************
bool DrawText::doesLineIntersect(
    const std::vector<std::shared_ptr<StringRect>> &rects, const Point2D &cds,
    const Point2D &end1, const Point2D &end2, double padding) const {
  for (auto r : rects) {
    StringRect nr(*r);
    nr.trans_ += cds;

    Point2D tl, tr, bl, br;
    nr.calcCorners(tl, tr, br, bl, padding);
    if (doLinesIntersect(end2, end1, tl, tr, nullptr)) {
      return true;
    }
    if (doLinesIntersect(end2, end1, tr, br, nullptr)) {
      return true;
    }
    if (doLinesIntersect(end2, end1, br, bl, nullptr)) {
      return true;
    }
    if (doLinesIntersect(end2, end1, bl, tl, nullptr)) {
      return true;
    }
  }
  return false;
}

// ****************************************************************************
bool DrawText::doesStringIntersect(const std::string &label1,
                                   OrientType orient1, const Point2D &cds1,
                                   const std::string &label2,
                                   OrientType orient2,
                                   const Point2D &cds2) const {
  if (label1.empty() || label2.empty()) {
    return false;
  }
  std::vector<std::shared_ptr<StringRect>> rects1;
  std::vector<TextDrawType> draw_modes1;
  std::vector<char> draw_chars1;

  getStringRects(label1, orient1, rects1, draw_modes1, draw_chars1);

  return doesStringIntersect(rects1, cds1, label2, orient2, cds2);
}

// ****************************************************************************
bool DrawText::doesStringIntersect(
    const std::vector<std::shared_ptr<StringRect>> &rects, const Point2D &cds1,
    const std::string &label2, OrientType orient2, const Point2D &cds2) const {
  if (label2.empty()) {
    return false;
  }
  std::vector<std::shared_ptr<StringRect>> rects2;
  std::vector<TextDrawType> draw_modes2;
  std::vector<char> draw_chars2;
  getStringRects(label2, orient2, rects2, draw_modes2, draw_chars2);

  for (auto r1 : rects) {
    StringRect nr1(*r1);
    nr1.trans_ += cds1;
    for (auto r2 : rects2) {
      StringRect nr2(*r2);
      nr2.trans_ += cds2;
      if (nr1.doesItIntersect(nr2)) {
        return true;
      }
    }
  }
  return false;
}

// ****************************************************************************
void DrawText::getStringExtremes(const std::string &label, OrientType orient,
                                 double &x_min, double &y_min, double &x_max,
                                 double &y_max, bool dontSplit) const {
  if (label.empty()) {
    x_min = x_max = 0.0;
    y_min = y_max = 0.0;
    return;
  }

  x_min = y_min = std::numeric_limits<double>::max();
  x_max = y_max = -std::numeric_limits<double>::max();

  std::vector<std::shared_ptr<StringRect>> rects;
  std::vector<TextDrawType> draw_modes;
  std::vector<char> to_draw;
  getStringRects(label, orient, rects, draw_modes, to_draw, dontSplit);

  int i = 0;
  for (auto r : rects) {
    Point2D tl, tr, br, bl;
    r->calcCorners(tl, tr, br, bl, 0.0);
    // sometimes the rect is in a coordinate frame where +ve y is down,
    // sometimes it's up.  For these purposes, we don't care so long as
    // the y_max is larger than the y_min.  We probably don't need to do
    // all the tests for x_min and x_max;
    x_min = std::min(bl.x, x_min);
    x_min = std::min(tr.x, x_min);
    y_min = std::min(bl.y, y_min);
    y_min = std::min(tr.y, y_min);
    x_max = std::max(bl.x, x_max);
    x_max = std::max(tr.x, x_max);
    y_max = std::max(bl.y, y_max);
    y_max = std::max(tr.y, y_max);
    ++i;
  }
}

// ****************************************************************************
void DrawText::alignString(
    TextAlignType talign, const std::vector<TextDrawType> &draw_modes,
    std::vector<std::shared_ptr<StringRect>> &rects) const {
  // std::string comes in with rects aligned with first char with its
  // left hand and bottom edges at 0 on y and x respectively.
  // Adjust relative to that so that the relative alignment point is at
  // (0,0).
  if (talign == TextAlignType::MIDDLE) {
    size_t num_norm = count(draw_modes.begin(), draw_modes.end(),
                            TextDrawType::TextDrawNormal);
    if (num_norm == 1) {
      talign = TextAlignType::START;
    }
  }

  Point2D align_trans, align_offset;
  if (talign == TextAlignType::START || talign == TextAlignType::END) {
    size_t align_char = 0;
    for (size_t i = 0; i < rects.size(); ++i) {
      if (draw_modes[i] == TextDrawType::TextDrawNormal) {
        align_char = i;
        if (talign == TextAlignType::START) {
          break;
        }
      }
    }
    align_trans = rects[align_char]->trans_;
    align_offset = rects[align_char]->offset_;
  } else {
    // centre on the middle of the Normal text.  The super- or subscripts
    // should be at the ends.
    double x_min = std::numeric_limits<double>::max();
    double x_max = -x_min;
    double y_min = std::numeric_limits<double>::max();
    double y_max = -y_min;
    align_offset.x = align_offset.y = 0.0;
    int num_norm = 0;
    for (size_t i = 0; i < rects.size(); ++i) {
      if (draw_modes[i] == TextDrawType::TextDrawNormal) {
        Point2D tl, tr, br, bl;
        rects[i]->calcCorners(tl, tr, br, bl, 0.0);
        // sometimes the rect is in a coordinate frame where +ve y is down,
        // sometimes it's up.  For these purposes, we don't care so long as
        // the y_max is larger than the y_min.  We probably don't need to do
        // all the tests for x_min and x_max;
        x_min = std::min(bl.x, x_min);
        x_min = std::min(tr.x, x_min);
        y_min = std::min(bl.y, y_min);
        y_min = std::min(tr.y, y_min);
        x_max = std::max(bl.x, x_max);
        x_max = std::max(tr.x, x_max);
        y_max = std::max(bl.y, y_max);
        y_max = std::max(tr.y, y_max);
        align_offset += rects[i]->offset_;
        ++num_norm;
      }
    }
    align_trans.x = (x_max - x_min) / 2.0;
    align_trans.y = 0.0;
    align_offset /= num_norm;
  }

  for (auto r : rects) {
    r->trans_ -= align_trans;
    r->offset_ = align_offset;
  }
}

// ****************************************************************************
void DrawText::adjustStringRectsForSuperSubScript(
    const std::vector<TextDrawType> &draw_modes,
    std::vector<std::shared_ptr<StringRect>> &rects) const {
  double last_char = -1;
  for (size_t i = 0; i < draw_modes.size(); ++i) {
    switch (draw_modes[i]) {
      case TextDrawType::TextDrawSuperscript:
        // superscripts may come before or after a letter.  If before,
        // spin through to first non-superscript for last_height
        if (last_char < 0) {
          for (size_t j = i + 1; j < draw_modes.size(); ++j) {
            if (draw_modes[j] == TextDrawType::TextDrawNormal) {
              last_char = j;
              break;
            }
          }
        }
        // adjust up by last height / 2.
        rects[i]->rect_corr_ = rects[last_char]->height_;
        rects[i]->trans_.y -= rects[i]->rect_corr_ / 2.0;
        // if the last char was a subscript, remove the advance
        if (i && draw_modes[i - 1] == TextDrawType::TextDrawSubscript) {
          double move_by = rects[i]->trans_.x - rects[i - 1]->trans_.x;
          if (move_by > 0.0) {
            for (size_t j = 0; j < i; ++j) {
              rects[j]->trans_.x += move_by;
            }
          } else {
            for (size_t j = i; j < draw_modes.size(); ++j) {
              rects[j]->trans_.x += move_by;
            }
          }
          rects[i]->trans_.x = rects[i - 1]->trans_.x;
        }
        break;
      case TextDrawType::TextDrawSubscript:
        // adjust y down by last height / 2
        rects[i]->rect_corr_ = -rects[last_char]->height_;
        rects[i]->trans_.y -= rects[i]->rect_corr_ / 2.0;
        // if the last char was a superscript, remove the advance
        if (i && draw_modes[i - 1] == TextDrawType::TextDrawSuperscript) {
          double move_by = rects[i]->trans_.x - rects[i - 1]->trans_.x;
          if (move_by > 0.0) {
            for (size_t j = 0; j < i; ++j) {
              rects[j]->trans_.x += move_by;
            }
          } else {
            for (size_t j = i; j < draw_modes.size(); ++j) {
              rects[j]->trans_.x += move_by;
            }
          }
          rects[i]->trans_.x = rects[i - 1]->trans_.x;
        }
        break;
      case TextDrawType::TextDrawNormal:
        last_char = i;
        break;
    }
  }
}

// ****************************************************************************
double DrawText::selectScaleFactor(char c, TextDrawType draw_type) const {
  switch (draw_type) {
    case TextDrawType::TextDrawNormal:
      return 1.0;
    case TextDrawType::TextDrawSubscript:
      return SUBS_SCALE;
    case TextDrawType::TextDrawSuperscript:
      if (c == '-' || c == '+') {
        return SUBS_SCALE;
      } else {
        return SUPER_SCALE;
      }
  }
  return 1.0;
}

// ****************************************************************************
void DrawText::getStringSize(const std::string &label, double &label_width,
                             double &label_height) const {
  double x_min, y_min, x_max, y_max;
  getStringExtremes(label, OrientType::E, x_min, y_min, x_max, y_max);
  label_width = x_max - x_min;
  label_height = y_max - y_min;
}

// ****************************************************************************
bool setStringDrawMode(const std::string &instring, TextDrawType &draw_mode,
                       size_t &i) {
  std::string bit1 = instring.substr(i, 5);
  std::string bit2 = instring.substr(i, 6);

  // could be markup for super- or sub-script
  if (std::string("<sub>") == bit1) {
    draw_mode = TextDrawType::TextDrawSubscript;
    i += 4;
    return true;
  } else if (std::string("<sup>") == bit1) {
    draw_mode = TextDrawType::TextDrawSuperscript;
    i += 4;
    return true;
  } else if (std::string("</sub>") == bit2) {
    draw_mode = TextDrawType::TextDrawNormal;
    i += 5;
    return true;
  } else if (std::string("</sup>") == bit2) {
    draw_mode = TextDrawType::TextDrawNormal;
    i += 5;
    return true;
  }

  return false;
}

// ****************************************************************************
void DrawText::getStringRects(const std::string &text, OrientType orient,
                              std::vector<std::shared_ptr<StringRect>> &rects,
                              std::vector<TextDrawType> &draw_modes,
                              std::vector<char> &draw_chars,
                              bool dontSplit) const {
  std::vector<std::string> text_bits;
  if (!dontSplit) {
    text_bits = atomLabelToPieces(text, orient);
  } else {
    text_bits.push_back(text);
  }

  if (orient == OrientType::W) {
    // stick the pieces together again backwards and draw as one so there
    // aren't ugly splits in the string.
    std::string new_lab;
    for (auto i = text_bits.rbegin(); i != text_bits.rend(); ++i) {
      new_lab += *i;
    }
    getStringRects(new_lab, rects, draw_modes, draw_chars);
    alignString(TextAlignType::END, draw_modes, rects);
  } else if (orient == OrientType::E) {
    // likewise, but forwards
    std::string new_lab;
    for (auto lab : text_bits) {
      new_lab += lab;
    }
    getStringRects(new_lab, rects, draw_modes, draw_chars);
    alignString(TextAlignType::START, draw_modes, rects);
  } else {
    double running_y = 0;
    for (size_t i = 0; i < text_bits.size(); ++i) {
      std::vector<std::shared_ptr<StringRect>> t_rects;
      std::vector<TextDrawType> t_draw_modes;
      std::vector<char> t_draw_chars;
      getStringRects(text_bits[i], t_rects, t_draw_modes, t_draw_chars);
      alignString(TextAlignType::MIDDLE, t_draw_modes, t_rects);
      double max_height = -std::numeric_limits<double>::max();
      for (auto r : t_rects) {
        max_height = std::max(r->height_, max_height);
        r->y_shift_ = running_y;
      }
      rects.insert(rects.end(), t_rects.begin(), t_rects.end());
      draw_modes.insert(draw_modes.end(), t_draw_modes.begin(),
                        t_draw_modes.end());
      draw_chars.insert(draw_chars.end(), t_draw_chars.begin(),
                        t_draw_chars.end());
      if (orient == OrientType::N) {
        running_y -= 1.1 * max_height;
      } else if (orient == OrientType::S) {
        running_y += 1.1 * max_height;
      }
    }
  }
}

// ****************************************************************************
void DrawText::drawChars(const Point2D &a_cds,
                         const std::vector<std::shared_ptr<StringRect>> &rects,
                         const std::vector<TextDrawType> &draw_modes,
                         const std::vector<char> &draw_chars) {
  double full_scale = fontScale();
  for (size_t i = 0; i < rects.size(); ++i) {
    Point2D draw_cds;
    draw_cds.x = a_cds.x + rects[i]->trans_.x - rects[i]->offset_.x;
    draw_cds.y = a_cds.y - rects[i]->trans_.y +
                 rects[i]->offset_.y;  // opposite sign convention
    draw_cds.y -= rects[i]->rect_corr_ + rects[i]->y_shift_;
    double mfs = minFontSize();
    setMinFontSize(-1);
    setFontScale(full_scale * selectScaleFactor(draw_chars[i], draw_modes[i]));
    drawChar(draw_chars[i], draw_cds);
    setMinFontSize(mfs);
    setFontScale(full_scale);
  }
}

// ****************************************************************************
std::vector<std::string> atomLabelToPieces(const std::string &label,
                                           OrientType orient) {
  // cout << "splitting " << label << " : " << orient << endl;
  std::vector<std::string> label_pieces;
  if (label.empty()) {
    return label_pieces;
  }

  // if we have the mark-up <lit>XX</lit> the symbol is to be used
  // without modification
  if (label.substr(0, 5) == "<lit>") {
    std::string lit_sym = label.substr(5);
    size_t idx = lit_sym.find("</lit>");
    if (idx != std::string::npos) {
      lit_sym = lit_sym.substr(0, idx);
    }
    label_pieces.emplace_back(lit_sym);
    return label_pieces;
  }

  std::string next_piece;
  size_t i = 0;
  while (true) {
    if (i == label.length()) {
      if (!next_piece.empty()) {
        label_pieces.emplace_back(next_piece);
        break;
      }
    }
    if (label.substr(i, 2) == "<s" || label[i] == ':' || isupper(label[i])) {
      // save the old piece, start a new one
      if (!next_piece.empty()) {
        label_pieces.emplace_back(next_piece);
        next_piece.clear();
      }
    }
    next_piece += label[i++];
  }
  if (label_pieces.size() < 2) {
    return label_pieces;
  }

  // if the orientation is S or E, any charge flag needs to be at the end.
  if (orient == OrientType::E || orient == OrientType::S) {
    for (size_t i = 0; i < label_pieces.size(); ++i) {
      if (label_pieces[i] == "<sup>+</sup>" ||
          label_pieces[i] == "<sup>-</sup>") {
        label_pieces.push_back(label_pieces[i]);
        label_pieces[i].clear();
        break;
      }
    }
  }

  // Now group some together.  This relies on the order that
  // getAtomLabel built them in the first place.  Each atom symbol
  // needs to be flanked by any <sub> and <super> pieces.
  std::vector<std::string> final_pieces;
  std::string curr_piece;
  bool had_symbol = false;
  for (const auto &p : label_pieces) {
    if (p.empty()) {
      continue;
    }
    if (!isupper(p[0])) {
      curr_piece += p;
    } else {
      if (had_symbol) {
        final_pieces.push_back(curr_piece);
        curr_piece = p;
        had_symbol = true;
      } else {
        curr_piece += p;
        had_symbol = true;
      }
    }
  }
  if (!curr_piece.empty()) {
    final_pieces.push_back(curr_piece);
  }

  // cout << "Final pieces : " << endl;
  // for(auto l: final_pieces) {
  //   cout << l << endl;
  // }
  // cout << endl;

  return final_pieces;
}

std::ostream &operator<<(std::ostream &oss, const TextAlignType &tat) {
  switch (tat) {
    case TextAlignType::START:
      oss << "START";
      break;
    case TextAlignType::MIDDLE:
      oss << "MIDDLE";
      break;
    case TextAlignType::END:
      oss << "END";
      break;
  }
  return oss;
}
std::ostream &operator<<(std::ostream &oss, const TextDrawType &tdt) {
  switch (tdt) {
    case TextDrawType::TextDrawNormal:
      oss << "TextDrawNormal";
      break;
    case TextDrawType::TextDrawSuperscript:
      oss << "TextDrawSuperscript";
      break;
    case TextDrawType::TextDrawSubscript:
      oss << "TextDrawSubscript";
      break;
  }
  return oss;
}
std::ostream &operator<<(std::ostream &oss, const OrientType &o) {
  switch (o) {
    case OrientType::C:
      oss << "C";
      break;
    case OrientType::N:
      oss << "N";
      break;
    case OrientType::S:
      oss << "S";
      break;
    case OrientType::E:
      oss << "E";
      break;
    case OrientType::W:
      oss << "W";
      break;
  }
  return oss;
}

}  // namespace RDKit