linux_utils.cpp

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#include "linux_utils.hpp"
 
#include <sys/utsname.h>
 
int UtilsOSDependable::convert_16_bit_to_8_bit(const std::string& hex16){
  try{
      unsigned long value = std::stoul(hex16, nullptr, 16);
      return static_cast<int>(value / 256);  
  } catch (...){
      return 0; 
  }
}
 
tuple<int, int, int> UtilsOSDependable::parse_terminal_color_response(const string& response){
  const size_t start_pos = response.find("rgb:");
  if (start_pos == string::npos){
      return {0, 0, 0};
  }
 
  const size_t end_pos = response.find("\033\\", start_pos);
  if (end_pos == string::npos){
      return {0, 0, 0};
  }
 
  string rgb_str = response.substr(start_pos + 4, end_pos - (start_pos + 4));
 
  replace(rgb_str.begin(), rgb_str.end(), '/', ' ');
 
  istringstream iss(rgb_str);
  string r_hex, g_hex, b_hex;
  iss >> r_hex >> g_hex >> b_hex;
 
  int r = convert_16_bit_to_8_bit(r_hex);
  int g = convert_16_bit_to_8_bit(g_hex);
  int b = convert_16_bit_to_8_bit(b_hex);
 
  return {r, g, b};
}
 
string UtilsOSDependable::capture_terminal_response(){
  termios oldt, newt;
  tcgetattr(STDIN_FILENO, &oldt);
  newt = oldt;
  newt.c_lflag &= ~(ICANON | ECHO);
  tcsetattr(STDIN_FILENO, TCSANOW, &newt);
 
  int oldf = fcntl(STDIN_FILENO, F_GETFL, 0);
  fcntl(STDIN_FILENO, F_SETFL, oldf | O_NONBLOCK);
 
  cout << "\033]11;?\033\\";
  cout.flush();
 
  string response;
  char ch;
  timeval tv;
  tv.tv_sec = 0;
  tv.tv_usec = 100000; // 100ms timeout
 
  fd_set readfds;
  FD_ZERO(&readfds);
  FD_SET(STDIN_FILENO, &readfds);
 
  while (select(STDIN_FILENO + 1, &readfds, NULL, NULL, &tv) > 0){
      if (read(STDIN_FILENO, &ch, 1) > 0){
          response += ch;
      } else{
          break;
      }
  }
 
  tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
  fcntl(STDIN_FILENO, F_SETFL, oldf);
 
  return response;
}
 
float UtilsOSDependable::get_terminal_bg_color_luminance(){
  if (!isatty(STDOUT_FILENO)){
      return 0;
  }
 
  string color_str = capture_terminal_response();
  auto [r, g, b] = parse_terminal_color_response(color_str);
  float luminance = 0.2126 * (r / 255.0) + 0.7152 * (g / 255.0) + 0.0722 * (b / 255.0);
  
  return luminance;
}
 
bool UtilsOSDependable::is_bg_color_dark(){
    return get_terminal_bg_color_luminance() <= 0.5;
}