qdebugstream.h

/*
 *  https://stackoverflow.com/questions/12978973/unknown-ouput-with-qdebugstream-and-qtextedit
 *
 *  Joonhwan
*/


#ifndef Q_DEBUGSTREAM_H
#define Q_DEBUGSTREAM_H

#include <iostream>
#include <streambuf>
#include <string>
#include <QPlainTextEdit>

class QDebugStream : public std::basic_streambuf<char> {
public:
  QDebugStream(std::ostream &stream, QPlainTextEdit *text_edit)
      : m_stream(stream) {
    log_window = text_edit;
    m_old_buf = stream.rdbuf();
    stream.rdbuf(this);
  }
  ~QDebugStream() {
    // output anything that is left
    if (!m_string.empty())
      log_window->appendPlainText(m_string.c_str());

    m_stream.rdbuf(m_old_buf);
  }

protected:
  virtual int_type overflow(int_type v) {
    if (v == '\n') {
      log_window->appendPlainText(m_string.c_str());
      m_string.erase(m_string.begin(), m_string.end());
    } else
      m_string += v;

    return v;
  }

  virtual std::streamsize xsputn(const char *p, std::streamsize n) {
    m_string.append(p, p + n);

    size_t pos = 0;
    while (pos != std::string::npos) {
      pos = m_string.find('\n');
      if (pos != std::string::npos) {
        std::string tmp(m_string.begin(), m_string.begin() + pos);
        log_window->appendPlainText(tmp.c_str());
        m_string.erase(m_string.begin(), m_string.begin() + pos + 1);
      }
    }

    return n;
  }

private:
  std::ostream &m_stream;
  std::streambuf *m_old_buf;
  std::string m_string;

  QPlainTextEdit *log_window;
};

#endif // Q_DEBUGSTREAM_H