Example Ttmedia_load_pat_cb

Example D-4 is an example of a typical algorithm of this callback.

Example D-4 Typical Algorithm of Ttmedia_load_pat_cb

Tt_message myAcmeSheetLoadCB(
         Tt_message      msg,
         void           *client_data,
         Tttk_op         op,
         Tt_status       diagnosis,
         unsigned char  *contents,
         int             len,
         char           *file,
         char           *docname 
) 
{
         Tt_status status = TT_OK;
         if (diagnosis != TT_OK) {
                 // toolkit detected an error
                 if (tt_message_status( msg ) == TT_WRN_START_MESSAGE) {
                         //
                         // Error is in start message!  We now have no
                         // reason to live, so tell main() to exit().
                         //
                         myAbortCode = 2;
                 }
                 // let toolkit handle the error
                 return msg;         }
         if ((op == TTME_COMPOSE) && (file == 0)) {
                 // open empty new buffer
         } else if (len > 0) {
                 // load contents into new buffer
         } else if (file != 0) {
                 if (ttdt_Get_Modified( msg, file, TT_BOTH, myCntxt, 5000 )) {
                         switch (myUserChoice( "Save, Revert, Ignore?" )) {
                             case 0:
                                 ttdt_Save( msg, file, TT_BOTH, myCntxt, 5000 );
                                 break;
                             case 1:
                                 ttdt_Revert( msg, file, TT_BOTH, myCntxt, 5000);
                                 break;
                         }
                 }
                 // load file into new buffer
         } else {
                 tttk_message_fail( msg, TT_DESKTOP_ENODATA, 0, 1 );
                 tt_free( contents ); tt_free( file ); tt_free( docname );
                 return 0;
         }
         int w, h, x, y = INT_MAX;
         ttdt_sender_imprint_on( 0, msg, 0, &w, &h, &x, &y, myCntxt, 5000 );
         positionMyWindowRelativeTo( w, h, x, y );
         if (maxBuffersAreNowOpen) {
                 // Un-volunteer to handle future requests until less busy
                 tt_ptype_undeclare( "Acme_Calc" );
         }
         if (tt_message_status( msg ) == TT_WRN_START_MESSAGE) {
                 //
                 // Join session before accepting start message,
                 // to prevent unnecessary starts of our ptype
                 // 
                ttdt_session_join( 0, myContractCB, myShell, 0, 1 );
         }
         ttdt_message_accept( msg, myContractCB, myShell, 0, 1, 1 );
         tt_free( contents ); tt_free( file ); tt_free( docname );
         return 0;
 }