improve UI feedback when cancelling a task

app/dialog/progress/progress.cpp

@@ -30,7 +30,8 @@
 namespace olive {
 
 ProgressDialog::ProgressDialog(const QString& message, const QString& title, QWidget *parent) :
-  QDialog(parent)
+  QDialog(parent),
+  show_progress_(true)
 {
   if (!title.isEmpty()) {
     setWindowTitle(title);
@@ -56,7 +57,19 @@ ProgressDialog::ProgressDialog(const QString& message, const QString& title, QWi
   cancel_layout->addStretch();
 
   QPushButton* cancel_btn = new QPushButton(tr("Cancel"));
-  connect(cancel_btn, &QPushButton::clicked, this, &ProgressDialog::Cancelled);
+
+  // Signal that derivatives can connect to
+  connect(cancel_btn, &QPushButton::clicked, this, &ProgressDialog::Cancelled, Qt::DirectConnection);
+
+  // Stop updating the elapsed/remaining timers
+  connect(cancel_btn, &QPushButton::clicked, elapsed_timer_lbl_, &ElapsedCounterWidget::Stop);
+
+  // Disable the button so that users know they don't need to keep clicking it
+  connect(cancel_btn, &QPushButton::clicked, this, &ProgressDialog::DisableSenderWidget);
+
+  // Prevent the progress bar from continuing to move
+  connect(cancel_btn, &QPushButton::clicked, this, &ProgressDialog::DisableProgressWidgets);
+
   cancel_layout->addWidget(cancel_btn);
 
   cancel_layout->addStretch();
@@ -80,6 +93,10 @@ void ProgressDialog::closeEvent(QCloseEvent *e)
 
 void ProgressDialog::SetProgress(double value)
 {
+  if (!show_progress_) {
+    return;
+  }
+
   int percent = qRound(100.0 * value);
 
   bar_->setValue(percent);
@@ -101,4 +118,14 @@ void ProgressDialog::ShowErrorMessage(const QString &title, const QString &messa
   b.exec();
 }
 
+void ProgressDialog::DisableSenderWidget()
+{
+  static_cast<QWidget*>(sender())->setEnabled(false);
+}
+
+void ProgressDialog::DisableProgressWidgets()
+{
+  show_progress_ = false;
+}
+
 }

app/dialog/progress/progress.h

@@ -54,6 +54,13 @@ private:
 
   ElapsedCounterWidget* elapsed_timer_lbl_;
 
+  bool show_progress_;
+
+private slots:
+  void DisableSenderWidget();
+
+  void DisableProgressWidgets();
+
 };
 
 }

app/widget/taskview/elapsedcounterwidget.cpp

@@ -65,6 +65,11 @@ void ElapsedCounterWidget::Start(qint64 start_time)
   UpdateTimers();
 }
 
+void ElapsedCounterWidget::Stop()
+{
+  elapsed_timer_.stop();
+}
+
 void ElapsedCounterWidget::UpdateTimers()
 {
   int64_t elapsed_ms, remaining_ms;

app/widget/taskview/elapsedcounterwidget.h

@@ -40,6 +40,9 @@ public:
   void Start();
   void Start(qint64 start_time);
 
+public slots:
+  void Stop();
+
 private:
   QLabel* elapsed_lbl_;