Qt: Delay showing game list refresh progress

Otherwise we spend more time updating the visuals than actually
scanning.

src/duckstation-qt/qthostinterface.cpp

@@ -339,7 +339,7 @@ void QtHostInterface::refreshGameList(bool invalidate_cache /* = false */, bool
   std::lock_guard<std::recursive_mutex> lock(m_settings_mutex);
   m_game_list->SetSearchDirectoriesFromSettings(*m_settings_interface.get());
 
-  QtProgressCallback progress(m_main_window);
+  QtProgressCallback progress(m_main_window, invalidate_cache ? 0.0f : 1.0f);
   m_game_list->Refresh(invalidate_cache, invalidate_database, &progress);
   emit gameListRefreshed();
 }

src/duckstation-qt/qtprogresscallback.cpp

@@ -4,13 +4,13 @@
 #include <QtWidgets/QMessageBox>
 #include <array>
 
-QtProgressCallback::QtProgressCallback(QWidget* parent_widget)
-  : QObject(parent_widget), m_dialog(QString(), QString(), 0, 1, parent_widget)
+QtProgressCallback::QtProgressCallback(QWidget* parent_widget, float show_delay)
+  : QObject(parent_widget), m_dialog(QString(), QString(), 0, 1, parent_widget), m_show_delay(show_delay)
 {
   m_dialog.setWindowTitle(tr("DuckStation"));
   m_dialog.setMinimumSize(QSize(500, 0));
   m_dialog.setModal(parent_widget != nullptr);
-  m_dialog.show();
+  checkForDelayedShow();
 }
 
 QtProgressCallback::~QtProgressCallback() = default;
@@ -37,20 +37,27 @@ void QtProgressCallback::SetTitle(const char* title)
 void QtProgressCallback::SetStatusText(const char* text)
 {
   BaseProgressCallback::SetStatusText(text);
-  m_dialog.setLabelText(QString::fromUtf8(text));
+  checkForDelayedShow();
+
+  if (m_dialog.isVisible())
+    m_dialog.setLabelText(QString::fromUtf8(text));
 }
 
 void QtProgressCallback::SetProgressRange(u32 range)
 {
   BaseProgressCallback::SetProgressRange(range);
-  m_dialog.setRange(0, m_progress_range);
+  checkForDelayedShow();
+
+  if (m_dialog.isVisible())
+    m_dialog.setRange(0, m_progress_range);
 }
 
 void QtProgressCallback::SetProgressValue(u32 value)
 {
   BaseProgressCallback::SetProgressValue(value);
+  checkForDelayedShow();
 
-  if (static_cast<u32>(m_dialog.value()) == m_progress_range)
+  if (!m_dialog.isVisible() || static_cast<u32>(m_dialog.value()) == m_progress_range)
     return;
 
   m_dialog.setValue(m_progress_value);
@@ -92,3 +99,16 @@ void QtProgressCallback::ModalInformation(const char* message)
 {
   QMessageBox::information(&m_dialog, tr("Information"), QString::fromUtf8(message));
 }
+
+void QtProgressCallback::checkForDelayedShow()
+{
+  if (m_dialog.isVisible())
+    return;
+
+  if (m_show_timer.GetTimeSeconds() >= m_show_delay)
+  {
+    m_dialog.setRange(0, m_progress_range);
+    m_dialog.setValue(m_progress_value);
+    m_dialog.show();
+  }
+}

src/duckstation-qt/qtprogresscallback.h

@@ -1,5 +1,6 @@
 #pragma once
 #include "common/progress_callback.h"
+#include "common/timer.h"
 #include <QtWidgets/QProgressDialog>
 
 class QtProgressCallback final : public QObject, public BaseProgressCallback
@@ -7,7 +8,7 @@ class QtProgressCallback final : public QObject, public BaseProgressCallback
   Q_OBJECT
 
 public:
-  QtProgressCallback(QWidget* parent_widget);
+  QtProgressCallback(QWidget* parent_widget, float show_delay = 0.0f);
   ~QtProgressCallback();
 
   bool IsCancelled() const override;
@@ -28,5 +29,9 @@ public:
   void ModalInformation(const char* message) override;
 
 private:
+  void checkForDelayedShow();
+
   QProgressDialog m_dialog;
+  Common::Timer m_show_timer;
+  float m_show_delay;
 };