qml: Cleanup BitcoinAmount

This merges BitcoinAmount with SendRecipient to simplify the qml
logic. By doing so, the conversions can be managed all in c++
against the satoshi member variable. Each recipient having its
own BitcoinAmount allows the amounts to be saved independantly
when there are multiple recipients.

Author: johnny9

src/qml/bitcoinamount.cpp

@@ -1,4 +1,4 @@
-// Copyright (c) 2024 The Bitcoin Core developers
+// Copyright (c) 2024-2025 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -7,19 +7,9 @@
 #include <QRegExp>
 #include <QStringList>
 
-
-BitcoinAmount::BitcoinAmount(QObject *parent) : QObject(parent)
+BitcoinAmount::BitcoinAmount(QObject* parent)
+    : QObject(parent)
 {
-    m_unit = Unit::BTC;
-}
-
-int BitcoinAmount::decimals(Unit unit)
-{
-    switch (unit) {
-    case Unit::BTC: return 8;
-    case Unit::SAT: return 0;
-    } // no default case, so the compiler can warn about missing cases
-    assert(false);
 }
 
 QString BitcoinAmount::sanitize(const QString &text)
@@ -43,6 +33,30 @@ QString BitcoinAmount::sanitize(const QString &text)
     return result;
 }
 
+qint64 BitcoinAmount::satoshi() const
+{
+    return m_satoshi;
+}
+
+void BitcoinAmount::setSatoshi(qint64 new_amount)
+{
+    m_isSet = true;
+    if (m_satoshi != new_amount) {
+        m_satoshi = new_amount;
+        Q_EMIT amountChanged();
+    }
+}
+
+void BitcoinAmount::clear()
+{
+    if (!m_isSet && m_satoshi == 0) {
+        return;
+    }
+    m_satoshi = 0;
+    m_isSet = false;
+    Q_EMIT amountChanged();
+}
+
 BitcoinAmount::Unit BitcoinAmount::unit() const
 {
     return m_unit;
@@ -58,97 +72,82 @@ QString BitcoinAmount::unitLabel() const
 {
     switch (m_unit) {
     case Unit::BTC: return "₿";
-    case Unit::SAT: return "Sat";
+    case Unit::SAT: return "sat";
     }
     assert(false);
 }
 
-QString BitcoinAmount::amount() const
+void BitcoinAmount::flipUnit()
 {
-    return m_amount;
+    if (m_unit == Unit::BTC) {
+        m_unit = Unit::SAT;
+    } else {
+        m_unit = Unit::BTC;
+    }
+    Q_EMIT unitChanged();
+    Q_EMIT amountChanged();
 }
 
-QString BitcoinAmount::satoshiAmount() const
+QString BitcoinAmount::satsToBtc(qint64 sat)
 {
-    return toSatoshis(m_amount);
-}
+    const bool negative = sat < 0;
+    qint64 absSat = negative ? -sat : sat;
 
-void BitcoinAmount::setAmount(const QString& new_amount)
-{
-    m_amount = sanitize(new_amount);
-    Q_EMIT amountChanged();
+    const qint64 wholePart = absSat / COIN;
+    const qint64 fracInt = absSat % COIN;
+    QString fracPart = QString("%1").arg(fracInt, 8, 10, QLatin1Char('0'));
+
+    QString result = QString::number(wholePart) + '.' + fracPart;
+    if (negative) {
+        result.prepend('-');
+    }
+    return result;
 }
 
-QString BitcoinAmount::toSatoshis(const QString& text) const
+QString BitcoinAmount::toDisplay() const
 {
+    if (!m_isSet) {
+        return "";
+    }
     if (m_unit == Unit::SAT) {
-        return text;
+        return QString::number(m_satoshi);
     } else {
-        return convert(text, m_unit);
+        return satsToBtc(m_satoshi);
     }
 }
 
-long long BitcoinAmount::toSatoshis(QString& amount, const Unit unit)
+qint64 BitcoinAmount::btcToSats(const QString& btcSanitized)
 {
-    int num_decimals = decimals(unit);
-
-    QStringList parts = amount.remove(' ').split(".");
+    if (btcSanitized.isEmpty() || btcSanitized == ".") return 0;
 
-    QString whole = parts[0];
-    QString decimals;
+    QString cleaned = btcSanitized;
+    if (cleaned.startsWith('.')) cleaned.prepend('0');
 
-    if(parts.size() > 1)
-    {
-        decimals = parts[1];
+    QStringList parts = cleaned.split('.');
+    const qint64 whole = parts[0].isEmpty() ? 0 : parts[0].toLongLong();
+    qint64 frac = 0;
+    if (parts.size() == 2) {
+        frac = parts[1].leftJustified(8, '0').toLongLong();
     }
-    QString str = whole + decimals.leftJustified(num_decimals, '0', true);
 
-    return str.toLongLong();
+    return whole * COIN + frac;
 }
 
-QString BitcoinAmount::convert(const QString& amount, Unit unit) const
+void BitcoinAmount::fromDisplay(const QString& text)
 {
-    if (amount == "") {
-        return amount;
-    }
-
-    QString result = amount;
-    int decimalPosition  = result.indexOf(".");
-
-    if (decimalPosition == -1) {
-        decimalPosition = result.length();
-        result.append(".");
+    if (text.trimmed().isEmpty()) {
+        clear();
+        return;
     }
 
-    if (unit == Unit::BTC) {
-        int numDigitsAfterDecimal = result.length() - decimalPosition - 1;
-        if (numDigitsAfterDecimal < 8) {
-            result.append(QString(8 - numDigitsAfterDecimal, '0'));
-        }
-        result.remove(decimalPosition, 1);
-
-        while (result.startsWith('0') && result.length() > 1) {
-            result.remove(0, 1);
-        }
-    } else if (unit == Unit::SAT) {
-        result.remove(decimalPosition, 1);
-        int newDecimalPosition = decimalPosition - 8;
-        if (newDecimalPosition < 1) {
-            result = QString("0").repeated(-newDecimalPosition) + result;
-            newDecimalPosition = 0;
-        }
-        result.insert(newDecimalPosition, ".");
-
-        while (result.endsWith('0') && result.contains('.')) {
-            result.chop(1);
-        }
-        if (result.endsWith('.')) {
-            result.chop(1);
-        }
-        if (result.startsWith('.')) {
-            result.insert(0, "0");
-        }
+    qint64 newSat = 0;
+    if (m_unit == Unit::BTC) {
+        QString sanitized = sanitize(text);
+        newSat = btcToSats(sanitized);
+    } else {
+        QString digitsOnly = text;
+        digitsOnly.remove(QRegExp("[^0-9]"));
+        newSat = digitsOnly.trimmed().isEmpty() ? 0 : digitsOnly.toLongLong();
     }
-
-    return result;
+    setSatoshi(newSat);
 }

src/qml/bitcoinamount.h

@@ -1,4 +1,4 @@
-// Copyright (c) 2024 The Bitcoin Core developers
+// Copyright (c) 2024-2025 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -15,8 +15,8 @@ class BitcoinAmount : public QObject
     Q_OBJECT
     Q_PROPERTY(Unit unit READ unit WRITE setUnit NOTIFY unitChanged)
     Q_PROPERTY(QString unitLabel READ unitLabel NOTIFY unitChanged)
-    Q_PROPERTY(QString amount READ amount WRITE setAmount NOTIFY amountChanged)
-    Q_PROPERTY(QString satoshiAmount READ satoshiAmount NOTIFY amountChanged)
+    Q_PROPERTY(QString display READ toDisplay WRITE fromDisplay NOTIFY amountChanged)
+    Q_PROPERTY(qint64 satoshi READ satoshi WRITE setSatoshi NOTIFY amountChanged)
 
 public:
     enum class Unit {
@@ -30,27 +30,28 @@ class BitcoinAmount : public QObject
     Unit unit() const;
     void setUnit(Unit unit);
     QString unitLabel() const;
-    QString amount() const;
-    void setAmount(const QString& new_amount);
-    QString satoshiAmount() const;
+
+    QString toDisplay() const;
+    void fromDisplay(const QString& new_amount);
+    qint64 satoshi() const;
+    void setSatoshi(qint64 new_amount);
 
 public Q_SLOTS:
-    QString sanitize(const QString& text);
-    QString convert(const QString& text, Unit unit) const;
-    QString toSatoshis(const QString& text) const;
+    void flipUnit();
+    void clear();
 
 Q_SIGNALS:
     void unitChanged();
-    void unitLabelChanged();
     void amountChanged();
 
 private:
-    long long toSatoshis(QString &amount, const Unit unit);
-    int decimals(Unit unit);
+    QString sanitize(const QString& text);
+    static QString satsToBtc(qint64 sat);
+    static qint64 btcToSats(const QString& btc);
 
-    Unit m_unit;
-    QString m_unitLabel;
-    QString m_amount;
+    qint64 m_satoshi{0};
+    bool m_isSet{false};
+    Unit m_unit{Unit::BTC};
 };
 
 #endif // BITCOIN_QML_BITCOINAMOUNT_H

src/qml/models/sendrecipient.cpp

@@ -3,10 +3,11 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <qml/models/sendrecipient.h>
-#include <qobjectdefs.h>
+
+#include <qml/bitcoinamount.h>
 
 SendRecipient::SendRecipient(QObject* parent)
-    : QObject(parent), m_address(""), m_label(""), m_amount(""), m_message("")
+    : QObject(parent), m_amount(new BitcoinAmount(this))
 {
 }
 
@@ -36,19 +37,11 @@ void SendRecipient::setLabel(const QString& label)
     }
 }
 
-QString SendRecipient::amount() const
+BitcoinAmount* SendRecipient::amount() const
 {
     return m_amount;
 }
 
-void SendRecipient::setAmount(const QString& amount)
-{
-    if (m_amount != amount) {
-        m_amount = amount;
-        Q_EMIT amountChanged();
-    }
-}
-
 QString SendRecipient::message() const
 {
     return m_message;
@@ -69,22 +62,17 @@ bool SendRecipient::subtractFeeFromAmount() const
 
 CAmount SendRecipient::cAmount() const
 {
-    // TODO: Figure out who owns the parsing of SendRecipient::amount to CAmount
-    if (m_amount == "") {
-        return 0;
-    }
-    return m_amount.toLongLong();
+    return m_amount->satoshi();
 }
 
 void SendRecipient::clear()
 {
     m_address = "";
     m_label = "";
-    m_amount = "";
+    m_amount->setSatoshi(0);
     m_message = "";
     m_subtractFeeFromAmount = false;
     Q_EMIT addressChanged();
     Q_EMIT labelChanged();
-    Q_EMIT amountChanged();
     Q_EMIT messageChanged();
 }

src/qml/models/sendrecipient.h

@@ -5,17 +5,18 @@
 #ifndef BITCOIN_QML_MODELS_SENDRECIPIENT_H
 #define BITCOIN_QML_MODELS_SENDRECIPIENT_H
 
+#include <qml/bitcoinamount.h>
+
 #include <QObject>
 #include <QString>
-#include <qml/bitcoinamount.h>
 
 class SendRecipient : public QObject
 {
     Q_OBJECT
     Q_PROPERTY(QString address READ address WRITE setAddress NOTIFY addressChanged)
     Q_PROPERTY(QString label READ label WRITE setLabel NOTIFY labelChanged)
-    Q_PROPERTY(QString amount READ amount WRITE setAmount NOTIFY amountChanged)
     Q_PROPERTY(QString message READ message WRITE setMessage NOTIFY messageChanged)
+    Q_PROPERTY(BitcoinAmount* amount READ amount CONSTANT)
 
 public:
     explicit SendRecipient(QObject* parent = nullptr);
@@ -26,7 +27,7 @@ class SendRecipient : public QObject
     QString label() const;
     void setLabel(const QString& label);
 
-    QString amount() const;
+    BitcoinAmount* amount() const;
     void setAmount(const QString& amount);
 
     QString message() const;
@@ -41,14 +42,13 @@ class SendRecipient : public QObject
 Q_SIGNALS:
     void addressChanged();
     void labelChanged();
-    void amountChanged();
     void messageChanged();
 
 private:
-    QString m_address;
-    QString m_label;
-    QString m_amount;
-    QString m_message;
+    QString m_address{""};
+    QString m_label{""};
+    QString m_message{""};
+    BitcoinAmount* m_amount;
     bool m_subtractFeeFromAmount{false};
 };
 

src/qml/models/sendrecipientslistmodel.cpp

@@ -27,7 +27,7 @@ QVariant SendRecipientsListModel::data(const QModelIndex& index, int role) const
     switch (role) {
     case AddressRole: return r->address();
     case LabelRole: return r->label();
-    case AmountRole: return r->amount();
+    case AmountRole: return r->amount()->toDisplay();
     case MessageRole: return r->message();
     default: return {};
     }