add fiat<->sat conversion methods and hook up UI

electrum/gui/qml/components/Receive.qml

@@ -81,16 +81,20 @@ Pane {
 
         TextField {
             id: amountFiat
+            visible: Config.fiatCurrency != ''
             font.family: FixedFont
             Layout.fillWidth: true
             inputMethodHints: Qt.ImhDigitsOnly
         }
 
         Label {
-            text: qsTr('EUR')
+            visible: Config.fiatCurrency != ''
+            text: Config.fiatCurrency
             color: Material.accentColor
         }
 
+        Item { visible: Config.fiatCurrency == ''; width: 1; height: 1; Layout.columnSpan: 2 }
+
         RowLayout {
             Layout.columnSpan: 4
             Layout.alignment: Qt.AlignHCenter
@@ -346,4 +350,29 @@ Pane {
         }
     }
 
+    Connections {
+        target: amount
+        function onTextChanged() {
+            if (amountFiat.activeFocus)
+                return
+            var a = Config.unitsToSats(amount.text)
+            amountFiat.text = Daemon.fiatValue(a)
+        }
+    }
+    Connections {
+        target: amountFiat
+        function onTextChanged() {
+            if (amountFiat.activeFocus) {
+                amount.text = Daemon.satoshiValue(amountFiat.text)
+            }
+        }
+    }
+    Connections {
+        target: Network
+        function onFiatUpdated() {
+            var a = Config.unitsToSats(amount.text)
+            amountFiat.text = Daemon.fiatValue(a)
+        }
+    }
+
 }

electrum/gui/qml/components/Send.qml

@@ -8,10 +8,10 @@ Pane {
 
     GridLayout {
         width: parent.width
-        columns: 4
+        columns: 6
 
         BalanceSummary {
-            Layout.columnSpan: 4
+            Layout.columnSpan: 6
             Layout.alignment: Qt.AlignHCenter
         }
 
@@ -21,7 +21,7 @@ Pane {
 
         TextField {
             id: address
-            Layout.columnSpan: 2
+            Layout.columnSpan: 4
             Layout.fillWidth: true
             font.family: FixedFont
             placeholderText: qsTr('Paste address or invoice')
@@ -46,11 +46,26 @@ Pane {
         }
 
         Label {
-            text: Config.baseUnit
+            text: Config.baseUnit + '  ' // add spaces for easy right margin
+            color: Material.accentColor
+        }
+
+        TextField {
+            id: amountFiat
+            visible: Config.fiatCurrency != ''
+            font.family: FixedFont
+            placeholderText: qsTr('Amount')
+            inputMethodHints: Qt.ImhPreferNumbers
+        }
+
+        Label {
+            visible: Config.fiatCurrency != ''
+            text: Config.fiatCurrency
             color: Material.accentColor
-            Layout.fillWidth: true
         }
 
+        Item { visible: Config.fiatCurrency == ''; height: 1; Layout.columnSpan: 2; Layout.fillWidth: true }
+
         Item { width: 1; height: 1 } // workaround colspan on baseunit messing up row above
 
         Label {
@@ -61,11 +76,11 @@ Pane {
             id: fee
             font.family: FixedFont
             placeholderText: qsTr('sat/vB')
-            Layout.columnSpan: 3
+            Layout.columnSpan: 5
         }
 
         RowLayout {
-            Layout.columnSpan: 4
+            Layout.columnSpan: 6
             Layout.alignment: Qt.AlignHCenter
             spacing: 10
 
@@ -94,6 +109,31 @@ Pane {
         }
     }
 
+    Connections {
+        target: amount
+        function onTextChanged() {
+            if (amountFiat.activeFocus)
+                return
+            var a = Config.unitsToSats(amount.text)
+            amountFiat.text = Daemon.fiatValue(a)
+        }
+    }
+    Connections {
+        target: amountFiat
+        function onTextChanged() {
+            if (amountFiat.activeFocus) {
+                amount.text = Daemon.satoshiValue(amountFiat.text)
+            }
+        }
+    }
+    Connections {
+        target: Network
+        function onFiatUpdated() {
+            var a = Config.unitsToSats(amount.text)
+            amountFiat.text = Daemon.fiatValue(a)
+        }
+    }
+
     // make clicking the dialog background move the scope away from textedit fields
     // so the keyboard goes away
     MouseArea {

electrum/gui/qml/qeapp.py

@@ -121,6 +121,8 @@ class ElectrumQmlApplication(QGuiApplication):
             'protocol_version': version.PROTOCOL_VERSION
         })
 
+        self._qeconfig.fiatCurrencyChanged.connect(self._qedaemon.setFiatCurrency)
+
         qInstallMessageHandler(self.message_handler)
 
         # get notified whether root QML document loads or not

electrum/gui/qml/qedaemon.py

@@ -1,4 +1,5 @@
 import os
+from decimal import Decimal
 
 from PyQt5.QtCore import pyqtProperty, pyqtSignal, pyqtSlot, QObject, QUrl
 from PyQt5.QtCore import Qt, QAbstractListModel, QModelIndex
@@ -7,6 +8,7 @@ from electrum.util import register_callback, get_new_wallet_name, WalletFileExce
 from electrum.logging import get_logger
 from electrum.wallet import Wallet, Abstract_Wallet
 from electrum.storage import WalletStorage, StorageReadWriteError
+from electrum.bitcoin import COIN
 
 from .qewallet import QEWallet
 
@@ -133,6 +135,32 @@ class QEDaemon(QObject):
             self._logger.error(str(e))
             self.walletOpenError.emit(str(e))
 
+    @pyqtSlot(str, result=str)
+    def fiatValue(self, satoshis):
+        rate = self.daemon.fx.exchange_rate()
+        try:
+            sd = Decimal(satoshis)
+            if sd == 0:
+                return ''
+        except:
+            return ''
+        return self.daemon.fx.value_str(satoshis,rate)
+
+    # TODO: move conversion to FxThread
+    @pyqtSlot(str, result=str)
+    def satoshiValue(self, fiat):
+        rate = self.daemon.fx.exchange_rate()
+        try:
+            fd = Decimal(fiat)
+        except:
+            return ''
+        v = fd / Decimal(rate) * COIN
+        return '' if v.is_nan() else self.daemon.config.format_amount(v)
+
+    @pyqtSlot()
+    def setFiatCurrency(self):
+        self.daemon.fx.set_currency(self.daemon.config.get('currency'))
+
     @pyqtProperty('QString')
     def path(self):
         return self._path