How to Paste HTML

Environment: Win 32

I was working on a project where I had to paste into textbox HTML, copied from the Browser. A quick search on "HTML Clipboard Format" in MSDN gives you an article that thoroughly explained how HTML is kept in the Clipboard. Unfortunately, this article tells you that it's kept in UTF-8 format without explaining how to convert from UTF-8 back to HTML. So I had do some research on my own.

UTF-8 is the format that allows using Unicode characters in ASCII text by embedding a special token, &#code;, into the text, where the code is Unicode code (in decimal format) for the symbol. For some symbols there are special names. An example " " is " "... You can jump to the specification if you need more examples.

Here is a UTF8ToHtml function, which converts from UTF-8 to HTML. The algorithm is not explained, but you can read more about it here.

//utf8 - pointer to UTF8 formatted text. dwSize - size of UTF8 text; ptr is the pointer to Output buffer.

//The OnClickedPastehtml is the handler for BN_CLICK event of the button in Dialog box. IDC_TEXT is the multiline text box.

void UTF8ToHtml(BYTE *utf8, DWORD dwSize, CHAR *ptr )
{
  int code;
  BYTE *end = utf8 + dwSize;
  while( utf8 < end )
  {
    code = 0;
    if( (*utf8 & 0xF0) == 0xF0  )
    {
      code = (((*utf8)&0x0F) << 18) | (((*(utf8+1))
        & 0x7F)<<12) | (((*(utf8+2)) & 0x7F)<<6)
        | ((*(utf8+3)) & 0x7F );
      utf8+=3;
    }
    else
    {
      if( (*utf8 & 0xE0) == 0xE0 )
      {
        code = (((*utf8)&0x1F) << 12) | (((*(utf8+1))
         & 0x7F)<<6 ) | ((*(utf8+2)) & 0x7F );
        utf8+=2;
      }
      else
      {
        if( (*utf8 & 0xC0) == 0xC0 )
        {
          code = (((*utf8)&0x3F) << 6) | ((*(utf8+1)) & 0x7F) ;
          utf8+=1;
        }
      }
    }


    if( code == 0 )
    {
      *ptr = *utf8;
    }
    else
    {
      char s[10];
      switch(code)
      {
      case 160:
        strcpy(s, "& ");
        break;
      case 34:
        strcpy(s, "&");
        break;
      case 36:
        strcpy( s, "&&");
        break;
      case 60:
        strcpy( s, "&<");
        break;
      case 62:
        strcpy( s, "&>");
        break;
      default:
        sprintf( s, "&#%d;", code );
        break;
      }
      strcpy( ptr, s );
      ptr += strlen(s)-1;
    }
    utf8++;
    ptr++;
  }
  *ptr = 0;
}

LRESULT CDialog::OnClickedPastehtml( WORD wNotifyCode, 
                                     WORD wID,
                                     HWND hWndCtl, 
                                     BOOL& bHandled)
{
  if (!OpenClipboard() )
    return 0; 
  UINT uHtmlFormat = RegisterClipboardFormat("HTML Format");
  UINT uFormat = uHtmlFormat;
  if( IsClipboardFormatAvailable( uHtmlFormat ) == FALSE )
  {
    if( IsClipboardFormatAvailable( CF_TEXT ) == FALSE )
      return 0;
    uFormat = CF_TEXT;
  }
  
  HGLOBAL   hglb;
  LPTSTR    lptstr;
  hglb = GetClipboardData(uFormat);
  if (hglb != NULL) 
  {
    lptstr = (LPTSTR)GlobalLock(hglb); 
    if (lptstr != NULL) 
    {
      char *ptr1 = strstr( lptstr, "<!--StartFragment-->");
      if( ptr1 != 0 )
      {
        ptr1 += 20;
        char * ptr2 = strstr( lptstr, "<!--EndFragment-->");
        int iSize = (ptr2 - ptr1);
        char * tmp = (char*)_alloca( iSize *2);
        UTF8ToHtml((BYTE*)ptr1, iSize, tmp );
        //memcpy(tmp, ptr1, iSize );
        //tmp[iSize] = 0;
        SetDlgItemText(IDC_TEXT, tmp );
      }
      else
        SetDlgItemText(IDC_TEXT, lptstr );
      GlobalUnlock(hglb); 
    }
  }
  CloseClipboard(); 
  return 0;
}