qml: allow pay while amount in edit mode

electrum/gui/qml/components/InvoiceDialog.qml

@@ -214,15 +214,10 @@ ElDialog {
                         }
 
                         ToolButton {
-                            visible: !amountContainer.editmode && invoice.canPay
+                            visible: !amountContainer.editmode
                             icon.source: '../../icons/pen.png'
                             icon.color: 'transparent'
-                            onClicked: {
-                                amountBtc.text = invoice.amount.satsInt == 0 ? '' : Config.formatSats(invoice.amount)
-                                amountMax.checked = invoice.amount.isMax
-                                amountContainer.editmode = true
-                                amountBtc.focus = true
-                            }
+                            onClicked: enterAmountEdit()
                         }
                         GridLayout {
                             visible: amountContainer.editmode
@@ -232,6 +227,9 @@ ElDialog {
                                 id: amountBtc
                                 fiatfield: amountFiat
                                 enabled: !amountMax.checked
+                                onTextAsSatsChanged: {
+                                    invoice.amountOverride = textAsSats
+                                }
                             }
 
                             Label {
@@ -250,7 +248,7 @@ ElDialog {
                                 checked: false
                                 onCheckedChanged: {
                                     if (activeFocus)
-                                        invoice.amount.isMax = checked
+                                        invoice.amountOverride.isMax = checked
                                 }
                             }
 
@@ -269,22 +267,18 @@ ElDialog {
                             }
                         }
                         ToolButton {
-                            visible: amountContainer.editmode
                             Layout.fillWidth: false
+                            visible: amountContainer.editmode
                             icon.source: '../../icons/confirmed.png'
                             icon.color: 'transparent'
-                            onClicked: {
-                                amountContainer.editmode = false
-                                invoice.amount = amountMax.checked ? MAX : Config.unitsToSats(amountBtc.text)
-                                invoiceAmountChanged()
-                            }
+                            onClicked: applyAmountEdit()
                         }
                         ToolButton {
-                            visible: amountContainer.editmode
                             Layout.fillWidth: false
+                            visible: amountContainer.editmode
                             icon.source: '../../icons/closebutton.png'
                             icon.color: 'transparent'
-                            onClicked: amountContainer.editmode = false
+                            onClicked: cancelAmountEdit()
                         }
                     }
 
@@ -438,8 +432,10 @@ ElDialog {
                 Layout.preferredWidth: 1
                 text: qsTr('Pay')
                 icon.source: '../../icons/confirmed.png'
-                enabled: invoice.invoiceType != Invoice.Invalid && invoice.canPay && !amountContainer.editmode
+                enabled: invoice.invoiceType != Invoice.Invalid && invoice.canPay
                 onClicked: {
+                    if (amountContainer.editmode)
+                        applyAmountEdit()
                     if (invoice_key == '') // save invoice if not retrieved from key
                         invoice.save_invoice()
                     dialog.close()
@@ -450,6 +446,24 @@ ElDialog {
 
     }
 
+    function enterAmountEdit() {
+        amountBtc.text = invoice.amount.satsInt == 0 ? '' : Config.formatSats(invoice.amount)
+        amountMax.checked = invoice.amount.isMax
+        amountContainer.editmode = true
+        amountBtc.focus = true
+    }
+
+    function applyAmountEdit() {
+        amountContainer.editmode = false
+        invoice.amount = amountMax.checked ? MAX : Config.unitsToSats(amountBtc.text)
+        invoiceAmountChanged()
+    }
+
+    function cancelAmountEdit() {
+        amountContainer.editmode = false
+        invoice.amountOverride.clear()
+    }
+
     Component.onCompleted: {
         if (invoice_key != '') {
             invoice.initFromKey(invoice_key)

electrum/gui/qml/qeinvoice.py

@@ -135,6 +135,8 @@ class QEInvoiceParser(QEInvoice):
     lnurlRetrieved = pyqtSignal()
     lnurlError = pyqtSignal([str,str], arguments=['code', 'message'])
 
+    amountOverrideChanged = pyqtSignal()
+
     _bip70PrResolvedSignal = pyqtSignal([PaymentRequest], arguments=['pr'])
 
     def __init__(self, parent=None):
@@ -151,6 +153,9 @@ class QEInvoiceParser(QEInvoice):
         self._timer.setSingleShot(True)
         self._timer.timeout.connect(self.updateStatusString)
 
+        self._amountOverride = QEAmount()
+        self._amountOverride.valueChanged.connect(self._on_amountoverride_value_changed)
+
         self._bip70PrResolvedSignal.connect(self._bip70_payment_request_resolved)
 
         self.clear()
@@ -203,6 +208,22 @@ class QEInvoiceParser(QEInvoice):
         self.determine_can_pay()
         self.invoiceChanged.emit()
 
+    @pyqtProperty(QEAmount, notify=amountOverrideChanged)
+    def amountOverride(self):
+        return self._amountOverride
+
+    @amountOverride.setter
+    def amountOverride(self, new_amount):
+        self._logger.debug(f'set new override amount {repr(new_amount)}')
+        self._amountOverride.copyFrom(new_amount)
+
+        self.determine_can_pay()
+        self.amountOverrideChanged.emit()
+
+    @pyqtSlot()
+    def _on_amountoverride_value_changed(self):
+        self.determine_can_pay()
+
     @pyqtProperty('quint64', notify=invoiceChanged)
     def time(self):
         return self._effectiveInvoice.time if self._effectiveInvoice else 0
@@ -316,18 +337,23 @@ class QEInvoiceParser(QEInvoice):
         self.canPay = False
         self.userinfo = ''
 
-        if self.amount.isEmpty: # unspecified amount
+        if not self.amountOverride.isEmpty:
+            amount = self.amountOverride
+        else:
+            amount = self.amount
+
+        if amount.isEmpty: # unspecified amount
             return
 
         if self.invoiceType == QEInvoice.Type.LightningInvoice:
             if self.status in [PR_UNPAID, PR_FAILED]:
-                if self.get_max_spendable_lightning() >= self.amount.satsInt:
+                if self.get_max_spendable_lightning() >= amount.satsInt:
                     lnaddr = self._effectiveInvoice._lnaddr
-                    if lnaddr.amount and self.amount.satsInt < lnaddr.amount * COIN:
+                    if lnaddr.amount and amount.satsInt < lnaddr.amount * COIN:
                         self.userinfo = _('Cannot pay less than the amount specified in the invoice')
                     else:
                         self.canPay = True
-                elif self.address and self.get_max_spendable_onchain() > self.amount.satsInt:
+                elif self.address and self.get_max_spendable_onchain() > amount.satsInt:
                     # TODO: validate address?
                     # TODO: subtract fee?
                     self.canPay = True
@@ -343,10 +369,10 @@ class QEInvoiceParser(QEInvoice):
                     }[self.status]
         elif self.invoiceType == QEInvoice.Type.OnchainInvoice:
             if self.status in [PR_UNPAID, PR_FAILED]:
-                if self.amount.isMax and self.get_max_spendable_onchain() > 0:
+                if amount.isMax and self.get_max_spendable_onchain() > 0:
                     # TODO: dust limit?
                     self.canPay = True
-                elif self.get_max_spendable_onchain() >= self.amount.satsInt:
+                elif self.get_max_spendable_onchain() >= amount.satsInt:
                     # TODO: subtract fee?
                     self.canPay = True
                 else:

electrum/gui/qml/qetypes.py

@@ -77,10 +77,12 @@ class QEAmount(QObject):
     def isEmpty(self):
         return not(self._is_max or self._amount_sat or self._amount_msat)
 
+    @pyqtSlot()
     def clear(self):
-        self.satsInt = 0
-        self.msatsInt = 0
-        self.isMax = False
+        self._amount_sat = 0
+        self._amount_msat = 0
+        self._is_max = False
+        self.valueChanged.emit()
 
     def copyFrom(self, amount):
         if not amount: