Revert "gui: Alternate row background based on txid"

This reverts commit 264f9c4d4f7c1aeb3e89eedddcd88e47e8bba938.

This was included in ElementsProject#569
which received no review, and is a backport of upstream PR
bitcoin/bitcoin#12578 which was
later closed. It leaks memory which is causing CI to fail.

src/qt/transactionview.cpp

@@ -26,49 +26,16 @@
 #include <QDoubleValidator>
 #include <QHBoxLayout>
 #include <QHeaderView>
-#include <QItemDelegate>
 #include <QLabel>
 #include <QLineEdit>
 #include <QMenu>
-#include <QPainter>
 #include <QPoint>
 #include <QScrollBar>
 #include <QTableView>
 #include <QTimer>
 #include <QUrl>
 #include <QVBoxLayout>
 
-class TransactionRecordDelegate : public QItemDelegate
-{
-    QSortFilterProxyModel* m_proxy;
-
-    void paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const
-    {
-        bool alternate = false;
-        QVariant previous_hash;
-
-        for (int row = 0; row <= index.row(); ++row) {
-            QModelIndex sibling = m_proxy->mapToSource(index.sibling(row, 0));
-            QVariant hash = sibling.data(TransactionTableModel::TxHashRole);
-            if (row == 0) {
-                previous_hash = hash;
-            } else if (hash != previous_hash) {
-                alternate = !alternate;
-                previous_hash = hash;
-            }
-        }
-
-        if (alternate) {
-            painter->fillRect(option.rect, option.palette.alternateBase());
-        }
-
-        QItemDelegate::paint(painter, option, index);
-    }
-
-public:
-    TransactionRecordDelegate(QSortFilterProxyModel* proxy) : m_proxy(proxy) {}
-};
-
 TransactionView::TransactionView(const PlatformStyle *platformStyle, QWidget *parent) :
     QWidget(parent)
 {
@@ -252,7 +219,7 @@ void TransactionView::setModel(WalletModel *_model)
 
         transactionView->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
         transactionView->setModel(transactionProxyModel);
-        transactionView->setItemDelegate(new TransactionRecordDelegate(transactionProxyModel));
+        transactionView->setAlternatingRowColors(true);
         transactionView->setSelectionBehavior(QAbstractItemView::SelectRows);
         transactionView->setSelectionMode(QAbstractItemView::ExtendedSelection);
         transactionView->horizontalHeader()->setSortIndicator(TransactionTableModel::Date, Qt::DescendingOrder);