Merge bitcoin#11316: [qt] Add use available balance in send coins dia…

…log (CryptAxe, promag)

d052e38 [qt] Add use available balance in send coins dialog (CryptAxe)

Pull request description:

  This is an alternative to bitcoin#11098 to handle bitcoin#11033 where a new button `Use available balance` is added to each entry. When activated, the available balance is calculated by using the coin control (if any) and then it's subtracted the remaining recipient amounts. If this amount is positive then the `Subtract fee from amount` is automatically selected.

  Comparing to bitcoin#11098, this has the advantage to avoid the fair amount division over the recipients and allows to fine adjust the amounts in multiple iterations.

  Started from @CryptAxe commit 89e9eda to credit some code.

  <img width="965" alt="screen shot 2017-09-13 at 01 32 44" src="https://user-images.githubusercontent.com/3534524/30354518-e1bee31c-9824-11e7-9354-300aa63cdfd0.png">
  <img width="964" alt="screen shot 2017-09-13 at 01 44 57" src="https://user-images.githubusercontent.com/3534524/30354598-5731ac9c-9825-11e7-9d5f-8781988ed219.png">

Tree-SHA512: 01d20c13fd8b6c2a0ca1d74d3a9027c6922e6dccd3b08e59d5a72636be7072ed5eca7ebc5d431299497dd3374e83753220ad4174d8bc46dadb4b2f54973036a5

src/qt/forms/sendcoinsentry.ui

@@ -151,7 +151,7 @@
      </widget>
     </item>
     <item row="2" column="1">
-     <layout class="QHBoxLayout" name="horizontalLayoutAmount" stretch="0,1">
+     <layout class="QHBoxLayout" name="horizontalLayoutAmount" stretch="0,1,0">
       <item>
        <widget class="BitcoinAmountField" name="payAmount"/>
       </item>
@@ -165,6 +165,13 @@
         </property>
        </widget>
       </item>
+      <item>
+       <widget class="QPushButton" name="useAvailableBalanceButton">
+        <property name="text">
+         <string>Use available balance</string>
+        </property>
+       </widget>
+      </item>
      </layout>
     </item>
     <item row="3" column="0">

src/qt/sendcoinsdialog.cpp

@@ -497,6 +497,7 @@ SendCoinsEntry *SendCoinsDialog::addEntry()
     entry->setModel(model);
     ui->entries->addWidget(entry);
     connect(entry, SIGNAL(removeEntry(SendCoinsEntry*)), this, SLOT(removeEntry(SendCoinsEntry*)));
+    connect(entry, SIGNAL(useAvailableBalance(SendCoinsEntry*)), this, SLOT(useAvailableBalance(SendCoinsEntry*)));
     connect(entry, SIGNAL(payAmountChanged()), this, SLOT(coinControlUpdateLabels()));
     connect(entry, SIGNAL(subtractFeeFromAmountChanged()), this, SLOT(coinControlUpdateLabels()));
 
@@ -707,6 +708,31 @@ void SendCoinsDialog::on_buttonMinimizeFee_clicked()
     minimizeFeeSection(true);
 }
 
+void SendCoinsDialog::useAvailableBalance(SendCoinsEntry* entry)
+{
+    // Get CCoinControl instance if CoinControl is enabled or create a new one.
+    CCoinControl coin_control;
+    if (model->getOptionsModel()->getCoinControlFeatures()) {
+        coin_control = *CoinControlDialog::coinControl;
+    }
+
+    // Calculate available amount to send.
+    CAmount amount = model->getBalance(&coin_control);
+    for (int i = 0; i < ui->entries->count(); ++i) {
+        SendCoinsEntry* e = qobject_cast<SendCoinsEntry*>(ui->entries->itemAt(i)->widget());
+        if (e && !e->isHidden() && e != entry) {
+            amount -= e->getValue().amount;
+        }
+    }
+
+    if (amount > 0) {
+      entry->checkSubtractFeeFromAmount();
+      entry->setAmount(amount);
+    } else {
+      entry->setAmount(0);
+    }
+}
+
 void SendCoinsDialog::setMinimumFee()
 {
     ui->customFee->setValue(GetRequiredFee(1000));

src/qt/sendcoinsdialog.h

@@ -79,6 +79,7 @@ private Q_SLOTS:
     void on_buttonChooseFee_clicked();
     void on_buttonMinimizeFee_clicked();
     void removeEntry(SendCoinsEntry* entry);
+    void useAvailableBalance(SendCoinsEntry* entry);
     void updateDisplayUnit();
     void coinControlFeatureChanged(bool);
     void coinControlButtonClicked();

src/qt/sendcoinsentry.cpp

@@ -50,6 +50,7 @@ SendCoinsEntry::SendCoinsEntry(const PlatformStyle *_platformStyle, QWidget *par
     connect(ui->deleteButton, SIGNAL(clicked()), this, SLOT(deleteClicked()));
     connect(ui->deleteButton_is, SIGNAL(clicked()), this, SLOT(deleteClicked()));
     connect(ui->deleteButton_s, SIGNAL(clicked()), this, SLOT(deleteClicked()));
+    connect(ui->useAvailableBalanceButton, SIGNAL(clicked()), this, SLOT(useAvailableBalanceClicked()));
 }
 
 SendCoinsEntry::~SendCoinsEntry()
@@ -114,11 +115,21 @@ void SendCoinsEntry::clear()
     updateDisplayUnit();
 }
 
+void SendCoinsEntry::checkSubtractFeeFromAmount()
+{
+    ui->checkboxSubtractFeeFromAmount->setChecked(true);
+}
+
 void SendCoinsEntry::deleteClicked()
 {
     Q_EMIT removeEntry(this);
 }
 
+void SendCoinsEntry::useAvailableBalanceClicked()
+{
+    Q_EMIT useAvailableBalance(this);
+}
+
 bool SendCoinsEntry::validate()
 {
     if (!model)
@@ -230,6 +241,11 @@ void SendCoinsEntry::setAddress(const QString &address)
     ui->payAmount->setFocus();
 }
 
+void SendCoinsEntry::setAmount(const CAmount &amount)
+{
+    ui->payAmount->setValue(amount);
+}
+
 bool SendCoinsEntry::isClear()
 {
     return ui->payTo->text().isEmpty() && ui->payTo_is->text().isEmpty() && ui->payTo_s->text().isEmpty();

src/qt/sendcoinsentry.h

@@ -38,6 +38,7 @@ class SendCoinsEntry : public QStackedWidget
 
     void setValue(const SendCoinsRecipient &value);
     void setAddress(const QString &address);
+    void setAmount(const CAmount &amount);
 
     /** Set up the tab chain manually, as Qt messes up the tab chain by default in some cases
      *  (issue https://bugreports.qt-project.org/browse/QTBUG-10907).
@@ -48,14 +49,17 @@ class SendCoinsEntry : public QStackedWidget
 
 public Q_SLOTS:
     void clear();
+    void checkSubtractFeeFromAmount();
 
 Q_SIGNALS:
     void removeEntry(SendCoinsEntry *entry);
+    void useAvailableBalance(SendCoinsEntry* entry);
     void payAmountChanged();
     void subtractFeeFromAmountChanged();
 
 private Q_SLOTS:
     void deleteClicked();
+    void useAvailableBalanceClicked();
     void on_payTo_textChanged(const QString &address);
     void on_addressBookButton_clicked();
     void on_pasteButton_clicked();