util.cc

/* util.cc
 *   by Trinity Quirk <tquirk@ymb.net>
 *   last updated 29 Nov 2019, 15:29:33 tquirk
 *
 * CuddlyGL OpenGL widget toolkit
 * Copyright (C) 2019  Trinity Annabelle Quirk
 *
 * This program 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 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 *
 * This file contains some string conversion functions.
 *
 * Things to do
 *
 */

#include "util.h"

/* We need to be able to convert from UTF-8 representation to
 * actual Unicode code points and back.  All network traffic
 * should be in UTF-8, and we'll of course need to display things
 * in whatever native font the user needs.
 *
 * Ref: http://www.cprogramming.com/tutorial/unicode.html
 * Ref: https://www.cl.cam.ac.uk/~mgk25/unicode.html
 */
std::u32string ui::utf8tou32str(const std::string& str)
{
    std::string::const_iterator i = str.begin();
    std::u32string newstr;
    uint32_t ch;

    while (i != str.end())
    {
        if ((*i & 0xfe) == 0xfc)
        {
            ch = (*i & 0x01) << 30;
            ch |= (*(++i) & 0x3f) << 24;
            ch |= (*(++i) & 0x3f) << 18;
            ch |= (*(++i) & 0x3f) << 12;
            ch |= (*(++i) & 0x3f) << 6;
            ch |= (*(++i) & 0x3f);
        }
        else if ((*i & 0xfc) == 0xf8)
        {
            ch = (*i & 0x03) << 24;
            ch |= (*(++i) & 0x3f) << 18;
            ch |= (*(++i) & 0x3f) << 12;
            ch |= (*(++i) & 0x3f) << 6;
            ch |= (*(++i) & 0x3f);
        }
        else if ((*i & 0xf8) == 0xf0)
        {
            ch = (*i & 0x07) << 18;
            ch |= (*(++i) & 0x3f) << 12;
            ch |= (*(++i) & 0x3f) << 6;
            ch |= (*(++i) & 0x3f);
        }
        else if ((*i & 0xf0) == 0xe0)
        {
            ch = (*i & 0x0f) << 12;
            ch |= (*(++i) & 0x3f) << 6;
            ch |= (*(++i) & 0x3f);
        }
        else if ((*i & 0xe0) == 0xc0)
        {
            ch = (*i & 0x1f) << 6;
            ch |= (*(++i) & 0x3f);
        }
        else if ((*i & 0x80) == 0x00)
            ch = *i;
        else
            ch = 0xfffd;

        newstr.push_back(ch);
        ++i;
    }
    return newstr;
}

std::string ui::u32strtoutf8(const std::u32string& str)
{
    std::u32string::const_iterator i = str.begin();
    std::string newstr;

    while (i != str.end())
    {
        if (*i & 0x7c000000)
        {
            newstr.push_back(0xfc | ((*i & 0x40000000) >> 30));
            newstr.push_back(0x80 | ((*i & 0x3f000000) >> 24));
            newstr.push_back(0x80 | ((*i & 0xfc0000) >> 18));
            newstr.push_back(0x80 | ((*i & 0x3f000) >> 12));
            newstr.push_back(0x80 | ((*i & 0xfc0) >> 6));
            newstr.push_back(0x80 | (*i & 0x3f));
        }
        else if (*i & 0x3e00000)
        {
            newstr.push_back(0xf8 | ((*i & 0x3000000) >> 24));
            newstr.push_back(0x80 | ((*i & 0xfc0000) >> 18));
            newstr.push_back(0x80 | ((*i & 0x3f000) >> 12));
            newstr.push_back(0x80 | ((*i & 0xfc0) >> 6));
            newstr.push_back(0x80 | (*i & 0x3f));
        }
        else if (*i & 0x1f0000)
        {
            newstr.push_back(0xf0 | ((*i & 0x1c0000) >> 18));
            newstr.push_back(0x80 | ((*i & 0x3f000) >> 12));
            newstr.push_back(0x80 | ((*i & 0xfc0) >> 6));
            newstr.push_back(0x80 | (*i & 0x3f));
        }
        else if (*i & 0xf800)
        {
            newstr.push_back(0xe0 | ((*i & 0x1f000) >> 12));
            newstr.push_back(0x80 | ((*i & 0xfc0) >> 6));
            newstr.push_back(0x80 | (*i & 0x3f));
        }
        else if (*i & 0x780)
        {
            newstr.push_back(0xc0 | ((*i & 0x7c0) >> 6));
            newstr.push_back(0x80 | (*i & 0x3f));
        }
        else
        {
            newstr.push_back(*i & 0x7f);
        }
        ++i;
    }

    return newstr;
}