2 files changed, 26 insertions, 11 deletions

diff --git a/src/qt/intro.cpp b/src/qt/intro.cpp
index cb7b13260a..873d9dcd6f 100644
--- a/src/qt/intro.cpp
+++ b/src/qt/intro.cpp
@@ -107,6 +107,15 @@ void FreespaceChecker::check()
     Q_EMIT reply(replyStatus, replyMessage, freeBytesAvailable);
 }
 
+namespace {
+//! Return pruning size that will be used if automatic pruning is enabled.
+int GetPruneTargetGB()
+{
+    int64_t prune_target_mib = gArgs.GetArg("-prune", 0);
+    // >1 means automatic pruning is enabled by config, 1 means manual pruning, 0 means no pruning.
+    return prune_target_mib > 1 ? PruneMiBtoGB(prune_target_mib) : DEFAULT_PRUNE_TARGET_GB;
+}
+} // namespace
 
 Intro::Intro(QWidget *parent, int64_t blockchain_size_gb, int64_t chain_state_size_gb) :
     QDialog(parent),
@@ -114,7 +123,8 @@ Intro::Intro(QWidget *parent, int64_t blockchain_size_gb, int64_t chain_state_si
     thread(nullptr),
     signalled(false),
     m_blockchain_size_gb(blockchain_size_gb),
-    m_chain_state_size_gb(chain_state_size_gb)
+    m_chain_state_size_gb(chain_state_size_gb),
+    m_prune_target_gb{GetPruneTargetGB()}
 {
     ui->setupUi(this);
     ui->welcomeLabel->setText(ui->welcomeLabel->text().arg(PACKAGE_NAME));
@@ -128,14 +138,18 @@ Intro::Intro(QWidget *parent, int64_t blockchain_size_gb, int64_t chain_state_si
     );
     ui->lblExplanation2->setText(ui->lblExplanation2->text().arg(PACKAGE_NAME));
 
-    int64_t prune_target_mib = std::max<int64_t>(0, gArgs.GetArg("-prune", 0));
-    if (prune_target_mib > 1) { // -prune=1 means enabled, above that it's a size in MiB
+    if (gArgs.GetArg("-prune", 0) > 1) { // -prune=1 means enabled, above that it's a size in MiB
         ui->prune->setChecked(true);
         ui->prune->setEnabled(false);
     }
-    const int prune_target_gb = PruneMiBtoGB(prune_target_mib);
-    ui->prune->setText(tr("Discard blocks after verification, except most recent %1 GB (prune)").arg(prune_target_gb ? prune_target_gb : DEFAULT_PRUNE_TARGET_GB));
-    UpdatePruneLabels(prune_target_gb);
+    ui->prune->setText(tr("Discard blocks after verification, except most recent %1 GB (prune)").arg(m_prune_target_gb));
+    UpdatePruneLabels(ui->prune->isChecked());
+
+    connect(ui->prune, &QCheckBox::toggled, [this](bool prune_checked) {
+        UpdatePruneLabels(prune_checked);
+        UpdateFreeSpaceLabel();
+    });
+
     startThread();
 }
 
@@ -337,15 +351,15 @@ QString Intro::getPathToCheck()
     return retval;
 }
 
-void Intro::UpdatePruneLabels(int64_t prune_target_gb)
+void Intro::UpdatePruneLabels(bool prune_checked)
 {
     m_required_space_gb = m_blockchain_size_gb + m_chain_state_size_gb;
     QString storageRequiresMsg = tr("At least %1 GB of data will be stored in this directory, and it will grow over time.");
-    if (0 < prune_target_gb && prune_target_gb <= m_blockchain_size_gb) {
-        m_required_space_gb = prune_target_gb + m_chain_state_size_gb;
+    if (prune_checked && m_prune_target_gb <= m_blockchain_size_gb) {
+        m_required_space_gb = m_prune_target_gb + m_chain_state_size_gb;
         storageRequiresMsg = tr("Approximately %1 GB of data will be stored in this directory.");
     }
-    ui->lblExplanation3->setVisible(prune_target_gb > 0);
+    ui->lblExplanation3->setVisible(prune_checked);
     ui->sizeWarningLabel->setText(
         tr("%1 will download and store a copy of the Bitcoin block chain.").arg(PACKAGE_NAME) + " " +
         storageRequiresMsg.arg(m_required_space_gb) + " " +
diff --git a/src/qt/intro.h b/src/qt/intro.h
index 8375847cc0..732393246e 100644
--- a/src/qt/intro.h
+++ b/src/qt/intro.h
@@ -72,11 +72,12 @@ private:
     //! Total required space (in GB) depending on user choice (prune or not prune).
     int64_t m_required_space_gb{0};
     uint64_t m_bytes_available{0};
+    const int64_t m_prune_target_gb;
 
     void startThread();
     void checkPath(const QString &dataDir);
     QString getPathToCheck();
-    void UpdatePruneLabels(int64_t prune_target_gb);
+    void UpdatePruneLabels(bool prune_checked);
     void UpdateFreeSpaceLabel();
 
     friend class FreespaceChecker;