task: improve threading

app/widget/taskview/elapsedcounterwidget.cpp

@@ -22,6 +22,7 @@
 
 #include <QDateTime>
 #include <QHBoxLayout>
+#include <cmath>
 
 #include "common/timecodefunctions.h"
 
@@ -80,7 +81,7 @@ void ElapsedCounterWidget::UpdateTimers()
     double ms_per_progress_unit = elapsed_ms / last_progress_;
     double remaining_progress = 1.0 - last_progress_;
 
-    remaining_ms = qRound64(ms_per_progress_unit * remaining_progress);
+    remaining_ms = std::ceil(ms_per_progress_unit * remaining_progress);
   } else {
     elapsed_ms = 0;
     remaining_ms = 0;

app/widget/taskview/elapsedcounterwidget.h

@@ -37,8 +37,9 @@ public:
 
   void SetProgress(double d);
 
-  void Start();
+public slots:
   void Start(qint64 start_time);
+  void Start();
 
 public slots:
   void Stop();

app/widget/taskview/taskviewitem.cpp

@@ -72,9 +72,9 @@ TaskViewItem::TaskViewItem(Task* task, QWidget *parent) :
 
   // Set up elapsed timer
   status_stack_->setCurrentWidget(elapsed_timer_lbl_);
-  elapsed_timer_lbl_->Start(task_->GetStartTime());
 
   // Connect to the task
+  connect(task_, &Task::Started, elapsed_timer_lbl_, qOverload<qint64>(&ElapsedCounterWidget::Start));
   connect(task_, &Task::ProgressChanged, this, &TaskViewItem::UpdateProgress);
   connect(cancel_btn_, &QPushButton::clicked, this, [this] { emit TaskCancelled(task_); });
 }