//
// Update the chart and the viewport periodically
//
private void chartUpdateTimer_Tick(object sender, EventArgs e)
{
WinChartViewer viewer = winChartViewer1;
// Enables auto scroll if the viewport is showing the latest data before the update
bool autoScroll = (currentIndex > 0) && (0.01 + viewer.getValueAtViewPort("x",
viewer.ViewPortLeft + viewer.ViewPortWidth) >= timeStamps[currentIndex - 1]);
// Get new data from the queue and append them to the data arrays
var packets = buffer.get();
if (packets.Count <= 0)
{
return;
}
// if data arrays have insufficient space, we need to remove some old data.
if (currentIndex + packets.Count >= sampleSize)
{
// For safety, we check if the queue contains too much data than the entire data arrays. If
// this is the case, we only use the latest data to completely fill the data arrays.
if (packets.Count > sampleSize)
{
packets = new ArraySegment <DataPacket>(packets.Array, packets.Count - sampleSize, sampleSize);
}
// Remove oldest data to leave space for new data. To avoid frequent removal, we ensure at
// least 5% empty space available after removal.
int originalIndex = currentIndex;
currentIndex = sampleSize * 95 / 100 - 1;
if (currentIndex > sampleSize - packets.Count)
{
currentIndex = sampleSize - packets.Count;
}
for (int i = 0; i < currentIndex; ++i)
{
int srcIndex = i + originalIndex - currentIndex;
timeStamps[i] = timeStamps[srcIndex];
dataSeriesA[i] = dataSeriesA[srcIndex];
dataSeriesB[i] = dataSeriesB[srcIndex];
}
}
// Append the data from the queue to the data arrays
for (int n = packets.Offset; n < packets.Offset + packets.Count; ++n)
{
DataPacket p = packets.Array[n];
timeStamps[currentIndex] = p.elapsedTime;
dataSeriesA[currentIndex] = p.series0;
dataSeriesB[currentIndex] = p.series1;
++currentIndex;
}
//
// As we added more data, we may need to update the full range.
//
double startDate = timeStamps[0];
double endDate = timeStamps[currentIndex - 1];
// Use the initialFullRange (which is 60 seconds in this demo) if this is sufficient.
double duration = endDate - startDate;
if (duration < initialFullRange)
{
endDate = startDate + initialFullRange;
}
// Update the new full data range to include the latest data
bool axisScaleHasChanged = viewer.updateFullRangeH("x", startDate, endDate,
Chart.KeepVisibleRange);
if (autoScroll)
{
// Scroll the viewport if necessary to display the latest data
double viewPortEndPos = viewer.getViewPortAtValue("x", timeStamps[currentIndex - 1]);
if (viewPortEndPos > viewer.ViewPortLeft + viewer.ViewPortWidth)
{
viewer.ViewPortLeft = viewPortEndPos - viewer.ViewPortWidth;
axisScaleHasChanged = true;
}
}
// Set the zoom in limit as a ratio to the full range
viewer.ZoomInWidthLimit = zoomInLimit / (viewer.getValueAtViewPort("x", 1) -
viewer.getValueAtViewPort("x", 0));
// Trigger the viewPortChanged event. Updates the chart if the axis scale has changed
// (scrolling or zooming) or if new data are added to the existing axis scale.
viewer.updateViewPort(axisScaleHasChanged || (duration < initialFullRange), false);
}
