implement seeking in playback window and add playback line in graphing view

re/graphingwindow.cpp

@@ -69,6 +69,13 @@ GraphingWindow::GraphingWindow(const QVector<CANFrame> *frames, QWidget *parent)
     itemTracer->setStyle(QCPItemTracer::tsCircle);
     itemTracer->setSize(20);
 
+    playbackPen.setWidth(1);
+    playbackPen.setColor(Qt::red);
+    playbackLine = new QCPItemStraightLine(ui->graphingView);
+    playbackLine->setSelectable(false);
+    playbackLine->setPen(playbackPen);
+    playbackLine->setVisible(false);
+
     // connect slot that ties some axis selections together (especially opposite axes):
     connect(ui->graphingView, SIGNAL(selectionChangedByUser()), this, SLOT(selectionChanged()));
     //connect up the mouse controls
@@ -329,6 +336,28 @@ void GraphingWindow::gotCenterTimeID(uint32_t ID, double timestamp)
     ui->graphingView->replot();
 }
 
+void GraphingWindow::gotPlaybackTimestamp(double timestamp)
+{
+    if (timestamp == INFINITY) {
+        playbackLine->setVisible(false);
+        return;
+    }
+    playbackLine->setVisible(true);
+    
+    // timestamp is always givin in seconds
+    if (Utility::timeStyle == TS_MICROS)
+        timestamp *= 1000000;
+    else if (Utility::timeStyle == TS_MILLIS)
+        timestamp *= 1000;
+    else if (Utility::timeStyle == TS_CLOCK)
+        timestamp += 3600; // offset of one hour needed
+
+    playbackLine->point1->setCoords(timestamp, 0);
+    playbackLine->point2->setCoords(timestamp, 1);
+
+    ui->graphingView->replot();
+}
+
 void GraphingWindow::titleDoubleClick(QMouseEvent* event, QCPTextElement* title)
 {
   Q_UNUSED(event)

re/graphingwindow.h

@@ -84,6 +84,7 @@ private slots:
     void editSelectedGraph();
     void updatedFrames(int);
     void gotCenterTimeID(uint32_t ID, double timestamp);
+    void gotPlaybackTimestamp(double timestamp);
     void resetView();
     void zoomIn();
     void zoomOut();
@@ -105,6 +106,8 @@ private:
     QCPSelectionDecorator *selDecorator;
     QCPItemText *locationText;
     QCPItemTracer *itemTracer;
+    QPen playbackPen;
+    QCPItemStraightLine *playbackLine;
     bool needScaleSetup; //do we need to set x,y graphing extents?
     bool useOpenGL;
     bool followGraphEnd;