Function ImTextCharToUtf8_inline

src/imgui/imgui.cpp:2571–2604

Based on stb_to_utf8() from github.com/nothings/stb/

// Based on stb_to_utf8() from github.com/nothings/stb/
static inline int ImTextCharToUtf8_inline(char* buf, int buf_size, unsigned int c)
{
    if (c < 0x80)
    {
        buf[0] = (char)c;
        return 1;
    }
    if (c < 0x800)
    {
        if (buf_size < 2) return 0;
        buf[0] = (char)(0xc0 + (c >> 6));
        buf[1] = (char)(0x80 + (c & 0x3f));
        return 2;
    }
    if (c < 0x10000)
    {
        if (buf_size < 3) return 0;
        buf[0] = (char)(0xe0 + (c >> 12));
        buf[1] = (char)(0x80 + ((c >> 6) & 0x3f));
        buf[2] = (char)(0x80 + ((c ) & 0x3f));
        return 3;
    }
    if (c <= 0x10FFFF)
    {
        if (buf_size < 4) return 0;
        buf[0] = (char)(0xf0 + (c >> 18));
        buf[1] = (char)(0x80 + ((c >> 12) & 0x3f));
        buf[2] = (char)(0x80 + ((c >> 6) & 0x3f));
        buf[3] = (char)(0x80 + ((c ) & 0x3f));
        return 4;
    }
    // Invalid code point, the max unicode is 0x10FFFF
    return 0;
}

int ImTextCharToUtf8(char out_buf[5], unsigned int c)
{