CAKE-43 | added the ability to enter an amount for xmr.to exchange in both currencies xmr and btc; added isReceiveAmountEntered to ExchangeViewModel; added receiveAmount and isBTCRequest to XMRTOTradeRequest; added isReceiveAmount to calculateAmount method of ExchangeProvider; fixed XMRTOExchangeProvider

lib/view_model/exchange/exchange_view_model.dart

@@ -48,6 +48,7 @@ abstract class ExchangeViewModelBase with Store {
     tradeState = ExchangeTradeStateInitial();
     _cryptoNumberFormat = NumberFormat()..maximumFractionDigits = 12;
     provider = providersForCurrentPair().first;
+    isReceiveAmountEntered = false;
     loadLimits();
   }
 
@@ -92,6 +93,8 @@ abstract class ExchangeViewModelBase with Store {
   @observable
   bool isReceiveAddressEnabled;
 
+  bool isReceiveAmountEntered;
+
   Limits limits;
 
   NumberFormat _cryptoNumberFormat;
@@ -138,7 +141,8 @@ abstract class ExchangeViewModelBase with Store {
 
     provider
         .calculateAmount(
-            from: depositCurrency, to: receiveCurrency, amount: _amount)
+            from: depositCurrency, to: receiveCurrency, amount: _amount,
+            isReceiveAmount: true)
         .then((amount) => _cryptoNumberFormat
             .format(amount)
             .toString()
@@ -159,7 +163,8 @@ abstract class ExchangeViewModelBase with Store {
     final _amount = double.parse(amount);
     provider
         .calculateAmount(
-            from: depositCurrency, to: receiveCurrency, amount: _amount)
+            from: depositCurrency, to: receiveCurrency, amount: _amount,
+            isReceiveAmount: false)
         .then((amount) => _cryptoNumberFormat
             .format(amount)
             .toString()
@@ -191,8 +196,10 @@ abstract class ExchangeViewModelBase with Store {
           from: depositCurrency,
           to: receiveCurrency,
           amount: depositAmount,
+          receiveAmount: receiveAmount,
           address: receiveAddress,
-          refundAddress: depositAddress);
+          refundAddress: depositAddress,
+          isBTCRequest: isReceiveAmountEntered);
       amount = depositAmount;
       currency = depositCurrency;
     }