From f193c57a63d8e66835873ff05ef8028fa87b427f Mon Sep 17 00:00:00 2001
From: "Wladimir J. van der Laan" <laanwj@gmail.com>
Date: Mon, 20 Jun 2011 21:31:42 +0200
Subject: [PATCH] introduce bitcoin amount field with split amount/decimals, to
 protect against mistakes (https://forum.bitcoin.org/index.php?topic=19168.0)

---
 bitcoin-qt.pro                  |  6 ++-
 src/qt/bitcoinamountfield.cpp   | 67 +++++++++++++++++++++++++++++++++
 src/qt/bitcoinamountfield.h     | 33 ++++++++++++++++
 src/qt/forms/sendcoinsdialog.ui | 39 +++++++++++--------
 src/qt/optionsdialog.cpp        |  8 ++--
 src/qt/sendcoinsdialog.cpp      |  1 -
 6 files changed, 130 insertions(+), 24 deletions(-)
 create mode 100644 src/qt/bitcoinamountfield.cpp
 create mode 100644 src/qt/bitcoinamountfield.h

diff --git a/bitcoin-qt.pro b/bitcoin-qt.pro
index 27703592..501695bd 100644
--- a/bitcoin-qt.pro
+++ b/bitcoin-qt.pro
@@ -68,7 +68,8 @@ HEADERS += src/qt/bitcoingui.h \
     src/qt/monitoreddatamapper.h \
     src/externui.h \
     src/qt/transactiondesc.h \
-    src/qt/transactiondescdialog.h
+    src/qt/transactiondescdialog.h \
+    src/qt/bitcoinamountfield.h
 SOURCES += src/qt/bitcoin.cpp src/qt/bitcoingui.cpp \
     src/qt/transactiontablemodel.cpp \
     src/qt/addresstablemodel.cpp \
@@ -98,7 +99,8 @@ SOURCES += src/qt/bitcoin.cpp src/qt/bitcoingui.cpp \
     src/qt/monitoreddatamapper.cpp \
     src/qt/transactiondesc.cpp \
     src/qt/transactiondescdialog.cpp \
-    src/qt/bitcoinstrings.cpp
+    src/qt/bitcoinstrings.cpp \
+    src/qt/bitcoinamountfield.cpp
 
 RESOURCES += \
     src/qt/bitcoin.qrc
diff --git a/src/qt/bitcoinamountfield.cpp b/src/qt/bitcoinamountfield.cpp
new file mode 100644
index 00000000..e475441f
--- /dev/null
+++ b/src/qt/bitcoinamountfield.cpp
@@ -0,0 +1,67 @@
+#include "bitcoinamountfield.h"
+
+#include <QLabel>
+#include <QLineEdit>
+#include <QRegExpValidator>
+#include <QHBoxLayout>
+#include <QKeyEvent>
+
+BitcoinAmountField::BitcoinAmountField(QWidget *parent):
+        QWidget(parent), amount(0), decimals(0)
+{
+    amount = new QLineEdit(this);
+    amount->setValidator(new QRegExpValidator(QRegExp("[0-9]+"), this));
+    amount->setAlignment(Qt::AlignRight|Qt::AlignVCenter);
+    amount->installEventFilter(this);
+    amount->setMaximumWidth(80);
+    decimals = new QLineEdit(this);
+    decimals->setValidator(new QRegExpValidator(QRegExp("[0-9]+"), this));
+    decimals->setMaxLength(8);
+    decimals->setAlignment(Qt::AlignLeft|Qt::AlignVCenter);
+    decimals->setMaximumWidth(75);
+
+    QHBoxLayout *layout = new QHBoxLayout(this);
+    layout->setSpacing(0);
+    layout->addWidget(amount);
+    layout->addWidget(new QLabel(QString(".")));
+    layout->addWidget(decimals);
+    layout->addStretch(1);
+
+    setFocusPolicy(Qt::TabFocus);
+    setLayout(layout);
+    setFocusProxy(amount);
+
+    // If one if the widgets changes, the combined content changes as well
+    connect(amount, SIGNAL(textChanged(QString)), this, SIGNAL(textChanged()));
+    connect(decimals, SIGNAL(textChanged(QString)), this, SIGNAL(textChanged()));
+}
+
+void BitcoinAmountField::setText(const QString &text)
+{
+    const QStringList parts = text.split(QString("."));
+    if(parts.size() == 2)
+    {
+        amount->setText(parts[0]);
+        decimals->setText(parts[1]);
+    }
+}
+
+QString BitcoinAmountField::text() const
+{
+    return amount->text() + QString(".") + decimals->text();
+}
+
+// Intercept '.' and ',' keys, if pressed focus a specified widget
+bool BitcoinAmountField::eventFilter(QObject *object, QEvent *event)
+{
+    Q_UNUSED(object);
+    if(event->type() == QEvent::KeyPress)
+    {
+        QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
+        if(keyEvent->key() == Qt::Key_Period || keyEvent->key() == Qt::Key_Comma)
+        {
+            decimals->setFocus();
+        }
+    }
+    return false;
+}
diff --git a/src/qt/bitcoinamountfield.h b/src/qt/bitcoinamountfield.h
new file mode 100644
index 00000000..2171578e
--- /dev/null
+++ b/src/qt/bitcoinamountfield.h
@@ -0,0 +1,33 @@
+#ifndef BITCOINFIELD_H
+#define BITCOINFIELD_H
+
+#include <QWidget>
+
+QT_BEGIN_NAMESPACE
+class QLineEdit;
+QT_END_NAMESPACE
+
+class BitcoinAmountField: public QWidget
+{
+    Q_OBJECT
+    Q_PROPERTY(QString text READ text WRITE setText NOTIFY textChanged USER true);
+public:
+    explicit BitcoinAmountField(QWidget *parent = 0);
+
+    void setText(const QString &text);
+    QString text() const;
+
+signals:
+    void textChanged();
+
+protected:
+    // Intercept '.' and ',' keys, if pressed focus a specified widget
+    bool eventFilter(QObject *object, QEvent *event);
+
+private:
+    QLineEdit *amount;
+    QLineEdit *decimals;
+};
+
+
+#endif // BITCOINFIELD_H
diff --git a/src/qt/forms/sendcoinsdialog.ui b/src/qt/forms/sendcoinsdialog.ui
index 595b7f40..3aaec1b5 100644
--- a/src/qt/forms/sendcoinsdialog.ui
+++ b/src/qt/forms/sendcoinsdialog.ui
@@ -52,22 +52,6 @@
        </property>
       </widget>
      </item>
-     <item row="4" column="1">
-      <widget class="QLineEdit" name="payAmount">
-       <property name="maximumSize">
-        <size>
-         <width>145</width>
-         <height>16777215</height>
-        </size>
-       </property>
-       <property name="toolTip">
-        <string>Amount of bitcoins to send (e.g. 0.05)</string>
-       </property>
-       <property name="alignment">
-        <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
-       </property>
-      </widget>
-     </item>
      <item row="3" column="2">
       <widget class="QPushButton" name="pasteButton">
        <property name="toolTip">
@@ -106,6 +90,13 @@
        </property>
       </widget>
      </item>
+     <item row="4" column="1">
+      <widget class="BitcoinAmountField" name="payAmount" native="true">
+       <property name="focusPolicy">
+        <enum>Qt::TabFocus</enum>
+       </property>
+      </widget>
+     </item>
     </layout>
    </item>
    <item>
@@ -173,6 +164,22 @@
    </item>
   </layout>
  </widget>
+ <customwidgets>
+  <customwidget>
+   <class>BitcoinAmountField</class>
+   <extends>QWidget</extends>
+   <header>bitcoinamountfield.h</header>
+   <container>1</container>
+  </customwidget>
+ </customwidgets>
+ <tabstops>
+  <tabstop>payTo</tabstop>
+  <tabstop>payAmount</tabstop>
+  <tabstop>pasteButton</tabstop>
+  <tabstop>addressBookButton</tabstop>
+  <tabstop>sendButton</tabstop>
+  <tabstop>buttonBox</tabstop>
+ </tabstops>
  <resources>
   <include location="../bitcoin.qrc"/>
  </resources>
diff --git a/src/qt/optionsdialog.cpp b/src/qt/optionsdialog.cpp
index 1bf123b2..1b5b2fef 100644
--- a/src/qt/optionsdialog.cpp
+++ b/src/qt/optionsdialog.cpp
@@ -1,5 +1,6 @@
 #include "optionsdialog.h"
 #include "optionsmodel.h"
+#include "bitcoinamountfield.h"
 #include "monitoreddatamapper.h"
 #include "guiutil.h"
 
@@ -31,7 +32,7 @@ private:
     QCheckBox *connect_socks4;
     QLineEdit *proxy_ip;
     QLineEdit *proxy_port;
-    QLineEdit *fee_edit;
+    BitcoinAmountField *fee_edit;
 
 signals:
 
@@ -195,12 +196,9 @@ MainOptionsPage::MainOptionsPage(QWidget *parent):
     fee_hbox->addSpacing(18);
     QLabel *fee_label = new QLabel(tr("Pay transaction &fee"));
     fee_hbox->addWidget(fee_label);
-    fee_edit = new QLineEdit();
-    fee_edit->setMaximumWidth(100);
+    fee_edit = new BitcoinAmountField();
     fee_edit->setToolTip(tr("Optional transaction fee per KB that helps make sure your transactions are processed quickly. Most transactions are 1KB. Fee 0.01 recommended."));
 
-    GUIUtil::setupAmountWidget(fee_edit, this);
-
     fee_label->setBuddy(fee_edit);
     fee_hbox->addWidget(fee_edit);
     fee_hbox->addStretch(1);
diff --git a/src/qt/sendcoinsdialog.cpp b/src/qt/sendcoinsdialog.cpp
index 01072c42..5f9ee18a 100644
--- a/src/qt/sendcoinsdialog.cpp
+++ b/src/qt/sendcoinsdialog.cpp
@@ -23,7 +23,6 @@ SendCoinsDialog::SendCoinsDialog(QWidget *parent, const QString &address) :
     ui->setupUi(this);
 
     GUIUtil::setupAddressWidget(ui->payTo, this);
-    GUIUtil::setupAmountWidget(ui->payAmount, this);
 
     // Set initial send-to address if provided
     if(!address.isEmpty())