Correctly limit overview transaction list

The way that the main overview page limits the number
of transactions displayed (currently 5) is not
an appropriate use of Qt. If it's run with a DEBUG
build of Qt, it'll result in a segfault in certain
relatively common situations. Instead of artificially
limiting the rowCount() in the subclassed proxy
filter, we hide/unhide the rows in the displaying
QListView upon any changes in the sorted proxy filter.

Github-Pull: bitcoin-core/gui/pull/704
Rebased-From: 08209c039ff4ca5be4982da7a2ab7a624117ce1a

4 files changed, 15 insertions, 25 deletions

diff --git a/src/qt/overviewpage.cpp b/src/qt/overviewpage.cpp
index 85a3c36f39..d47afa9874 100644
--- a/src/qt/overviewpage.cpp
+++ b/src/qt/overviewpage.cpp
@@ -264,7 +264,6 @@ void OverviewPage::setWalletModel(WalletModel *model)
         // Set up transaction list
         filter.reset(new TransactionFilterProxy());
         filter->setSourceModel(model->getTransactionTableModel());
-        filter->setLimit(NUM_ITEMS);
         filter->setDynamicSortFilter(true);
         filter->setSortRole(Qt::EditRole);
         filter->setShowInactive(false);
@@ -273,6 +272,10 @@ void OverviewPage::setWalletModel(WalletModel *model)
         ui->listTransactions->setModel(filter.get());
         ui->listTransactions->setModelColumn(TransactionTableModel::ToAddress);
 
+        connect(filter.get(), &TransactionFilterProxy::rowsInserted, this, &OverviewPage::LimitTransactionRows);
+        connect(filter.get(), &TransactionFilterProxy::rowsRemoved, this, &OverviewPage::LimitTransactionRows);
+        connect(filter.get(), &TransactionFilterProxy::rowsMoved, this, &OverviewPage::LimitTransactionRows);
+        LimitTransactionRows();
         // Keep up to date with wallet
         setBalance(model->getCachedBalance());
         connect(model, &WalletModel::balanceChanged, this, &OverviewPage::setBalance);
@@ -301,6 +304,16 @@ void OverviewPage::changeEvent(QEvent* e)
     QWidget::changeEvent(e);
 }
 
+// Only show most recent NUM_ITEMS rows
+void OverviewPage::LimitTransactionRows()
+{
+    if (filter && ui->listTransactions && ui->listTransactions->model() && filter.get() == ui->listTransactions->model()) {
+        for (int i = 0; i < filter->rowCount(); ++i) {
+            ui->listTransactions->setRowHidden(i, i >= NUM_ITEMS);
+        }
+    }
+}
+
 void OverviewPage::updateDisplayUnit()
 {
     if (walletModel && walletModel->getOptionsModel()) {
diff --git a/src/qt/overviewpage.h b/src/qt/overviewpage.h
index 56f45907db..e171ddf06a 100644
--- a/src/qt/overviewpage.h
+++ b/src/qt/overviewpage.h
@@ -60,6 +60,7 @@ private:
     std::unique_ptr<TransactionFilterProxy> filter;
 
 private Q_SLOTS:
+    void LimitTransactionRows();
     void updateDisplayUnit();
     void handleTransactionClicked(const QModelIndex &index);
     void updateAlerts(const QString &warnings);
diff --git a/src/qt/transactionfilterproxy.cpp b/src/qt/transactionfilterproxy.cpp
index 3be7e1a969..33ca74231f 100644
--- a/src/qt/transactionfilterproxy.cpp
+++ b/src/qt/transactionfilterproxy.cpp
@@ -17,7 +17,6 @@ TransactionFilterProxy::TransactionFilterProxy(QObject *parent) :
     typeFilter(ALL_TYPES),
     watchOnlyFilter(WatchOnlyFilter_All),
     minAmount(0),
-    limitRows(-1),
     showInactive(true)
 {
 }
@@ -92,25 +91,8 @@ void TransactionFilterProxy::setWatchOnlyFilter(WatchOnlyFilter filter)
     invalidateFilter();
 }
 
-void TransactionFilterProxy::setLimit(int limit)
-{
-    this->limitRows = limit;
-}
-
 void TransactionFilterProxy::setShowInactive(bool _showInactive)
 {
     this->showInactive = _showInactive;
     invalidateFilter();
 }
-
-int TransactionFilterProxy::rowCount(const QModelIndex &parent) const
-{
-    if(limitRows != -1)
-    {
-        return std::min(QSortFilterProxyModel::rowCount(parent), limitRows);
-    }
-    else
-    {
-        return QSortFilterProxyModel::rowCount(parent);
-    }
-}
diff --git a/src/qt/transactionfilterproxy.h b/src/qt/transactionfilterproxy.h
index fd9be52842..9b43981bc2 100644
--- a/src/qt/transactionfilterproxy.h
+++ b/src/qt/transactionfilterproxy.h
@@ -42,14 +42,9 @@ public:
     void setMinAmount(const CAmount& minimum);
     void setWatchOnlyFilter(WatchOnlyFilter filter);
 
-    /** Set maximum number of rows returned, -1 if unlimited. */
-    void setLimit(int limit);
-
     /** Set whether to show conflicted transactions. */
     void setShowInactive(bool showInactive);
 
-    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
-
 protected:
     bool filterAcceptsRow(int source_row, const QModelIndex & source_parent) const override;
 
@@ -60,7 +55,6 @@ private:
     quint32 typeFilter;
     WatchOnlyFilter watchOnlyFilter;
     CAmount minAmount;
-    int limitRows;
     bool showInactive;
 };