From 4935ac583bbdc289dd31a1caae3d711edef742b6 Mon Sep 17 00:00:00 2001
From: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>
Date: Sat, 22 May 2021 21:32:51 +0300
Subject: [PATCH] qt: Improve GUI responsiveness

QProgressDialog estimates the time the operation will take (based on
time for steps), and only shows itself if that estimate is beyond
minimumDuration. The default minimumDuration value is 4 seconds, and it
could make users think that the GUI is frozen.
---
 src/qt/bitcoingui.cpp       | 1 -
 src/qt/guiutil.cpp          | 7 +++++--
 src/qt/walletcontroller.cpp | 3 +++
 src/qt/walletview.cpp       | 1 -
 4 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/qt/bitcoingui.cpp b/src/qt/bitcoingui.cpp
index 17fffe208..53a0d4001 100644
--- a/src/qt/bitcoingui.cpp
+++ b/src/qt/bitcoingui.cpp
@@ -1375,7 +1375,6 @@ void BitcoinGUI::showProgress(const QString &title, int nProgress)
         progressDialog = new QProgressDialog(title, QString(), 0, 100);
         GUIUtil::PolishProgressDialog(progressDialog);
         progressDialog->setWindowModality(Qt::ApplicationModal);
-        progressDialog->setMinimumDuration(0);
         progressDialog->setAutoClose(false);
         progressDialog->setValue(0);
     } else if (nProgress == 100) {
diff --git a/src/qt/guiutil.cpp b/src/qt/guiutil.cpp
index d21f9074e..534680ffa 100644
--- a/src/qt/guiutil.cpp
+++ b/src/qt/guiutil.cpp
@@ -818,9 +818,12 @@ void PolishProgressDialog(QProgressDialog* dialog)
     // Workaround for macOS-only Qt bug; see: QTBUG-65750, QTBUG-70357.
     const int margin = TextWidth(dialog->fontMetrics(), ("X"));
     dialog->resize(dialog->width() + 2 * margin, dialog->height());
-#else
-    Q_UNUSED(dialog);
 #endif
+    // QProgressDialog estimates the time the operation will take (based on time
+    // for steps), and only shows itself if that estimate is beyond minimumDuration.
+    // The default minimumDuration value is 4 seconds, and it could make users
+    // think that the GUI is frozen.
+    dialog->setMinimumDuration(0);
 }
 
 int TextWidth(const QFontMetrics& fm, const QString& text)
diff --git a/src/qt/walletcontroller.cpp b/src/qt/walletcontroller.cpp
index c152689f0..aa26a0154 100644
--- a/src/qt/walletcontroller.cpp
+++ b/src/qt/walletcontroller.cpp
@@ -207,6 +207,9 @@ void WalletControllerActivity::showProgressDialog(const QString& label_text)
     m_progress_dialog->setCancelButton(nullptr);
     m_progress_dialog->setWindowModality(Qt::ApplicationModal);
     GUIUtil::PolishProgressDialog(m_progress_dialog);
+    // The setValue call forces QProgressDialog to start the internal duration estimation.
+    // See details in https://bugreports.qt.io/browse/QTBUG-47042.
+    m_progress_dialog->setValue(0);
 }
 
 void WalletControllerActivity::destroyProgressDialog()
diff --git a/src/qt/walletview.cpp b/src/qt/walletview.cpp
index 67cc42725..62bf706ad 100644
--- a/src/qt/walletview.cpp
+++ b/src/qt/walletview.cpp
@@ -330,7 +330,6 @@ void WalletView::showProgress(const QString &title, int nProgress)
         progressDialog = new QProgressDialog(title, tr("Cancel"), 0, 100);
         GUIUtil::PolishProgressDialog(progressDialog);
         progressDialog->setWindowModality(Qt::ApplicationModal);
-        progressDialog->setMinimumDuration(0);
         progressDialog->setAutoClose(false);
         progressDialog->setValue(0);
     } else if (nProgress == 100) {