Make z_anonsettxdelta work on a tx that is not in our wallet and fix calculation

src/wallet/rpcwallet.cpp

@@ -3724,17 +3724,17 @@ UniValue z_anonsettxdelta(const UniValue& params, bool fHelp, const CPubKey& myp
             + HelpExampleRpc("z_anonsettxdelta txid", "123")
          );
 
-    LOCK2(cs_main, pwalletMain->cs_wallet);
 
-    uint256 txid;
+    uint256 txid,hashBlock;
+    CTransaction tx;
     txid.SetHex(params[0].get_str());
 
-    if (!pwalletMain->mapWallet.count(txid))
-        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid or non-wallet transaction id!");
-    const CWalletTx& wtx = pwalletMain->mapWallet[txid];
+    LOCK(cs_main);
+    if (!GetTransaction(txid, tx, hashBlock, true))
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "No information available about transaction");
 
     // delta = shielded outputs - shielded inputs
-    int delta = wtx.vShieldedSpend.size() - wtx.vShieldedOutput.size();
+    int delta = tx.vShieldedOutput.size() - tx.vShieldedSpend.size();
     return delta;
 }