Zooming and Scrolling with Track Line (1) (Qt)

[Qt Widgets version] qtdemo/zoomscrolltrack.cpp

#include <QApplication>
#include <QPushButton>
#include <QMouseEvent>
#include <math.h>
#include <sstream>
#include <algorithm>
#include "zoomscrolltrack.h"


ZoomScrollTrack::ZoomScrollTrack(QWidget *parent) :
    QDialog(parent)
{
    //
    // Set up the GUI
    //

    setFixedSize(782, 376);
    setWindowTitle("Zooming and Scrolling with Track Line (1)");

    // The frame on the left side
    QFrame *frame = new QFrame(this);
    frame->setGeometry(4, 4, 120, 370);
    frame->setFrameShape(QFrame::StyledPanel);

    // Pointer push button
    QPushButton *pointerPB = new QPushButton(QIcon(":/icons/scroll_icon.png"), "Scroll", frame);
    pointerPB->setGeometry(4, 8, 112, 28);
    pointerPB->setStyleSheet("QPushButton { text-align:left; padding:5px}");
    pointerPB->setCheckable(true);

    // Zoom In push button
    QPushButton *zoomInPB = new QPushButton(QIcon(":/icons/zoomin_icon.png"), "Zoom In", frame);
    zoomInPB->setGeometry(4, 36, 112, 28);
    zoomInPB->setStyleSheet("QPushButton { text-align:left; padding:5px}");
    zoomInPB->setCheckable(true);

    // Zoom Out push button
    QPushButton *zoomOutPB = new QPushButton(QIcon(":/icons/zoomout_icon.png"), "Zoom Out", frame);
    zoomOutPB->setStyleSheet("QPushButton { text-align:left; padding:5px}");
    zoomOutPB->setGeometry(4, 64, 112, 28);
    zoomOutPB->setCheckable(true);

    // The Pointer/Zoom In/Zoom Out buttons form a button group
    mouseUsage = new QButtonGroup(frame);
    mouseUsage->addButton(pointerPB, Chart::MouseUsageScroll);
    mouseUsage->addButton(zoomInPB, Chart::MouseUsageZoomIn);
    mouseUsage->addButton(zoomOutPB, Chart::MouseUsageZoomOut);
    connect(mouseUsage, SIGNAL(buttonPressed(QAbstractButton*)),
        SLOT(onMouseUsageChanged(QAbstractButton*)));

    // Chart Viewer
    m_ChartViewer = new QChartViewer(this);
    m_ChartViewer->setGeometry(128, 4, 650, 350);
    connect(m_ChartViewer, SIGNAL(viewPortChanged()), SLOT(onViewPortChanged()));
    connect(m_ChartViewer, SIGNAL(mouseMovePlotArea(QMouseEvent*)),
        SLOT(onMouseMovePlotArea(QMouseEvent*)));

    // Horizontal scroll bar
    m_HScrollBar = new QScrollBar(Qt::Horizontal, this);
    m_HScrollBar->setGeometry(128, 356, 650, 17);
    connect(m_HScrollBar, SIGNAL(valueChanged(int)), SLOT(onHScrollBarChanged(int)));

    //
    // Initialize the chart
    //

    // Load the data
    loadData();

    // Initialize the QChartViewer
    initChartViewer(m_ChartViewer);

    // Initially set the mouse to drag to scroll mode
    pointerPB->click();

    // Trigger the ViewPortChanged event to draw the chart
    m_ChartViewer->updateViewPort(true, true);
}

ZoomScrollTrack::~ZoomScrollTrack()
{
    delete m_ranSeries;
    delete m_ChartViewer->getChart();
}

//
// Load the data
//
void ZoomScrollTrack::loadData()
{
    // In this example, we just use random numbers as data.
    m_ranSeries = new RanSeries(127);
    m_timeStamps = m_ranSeries->getDateSeries(1827, Chart::chartTime(2007, 1, 1), 86400);
    m_dataSeriesA = m_ranSeries->getSeries(1827, 150, -10, 10);
    m_dataSeriesB = m_ranSeries->getSeries(1827, 200, -10, 10);
    m_dataSeriesC = m_ranSeries->getSeries(1827, 250, -8, 8);
}

//
// Initialize the QChartViewer
//
void ZoomScrollTrack::initChartViewer(QChartViewer *viewer)
{
    // Set the full x range to be the duration of the data
    viewer->setFullRange("x", m_timeStamps[0], m_timeStamps[m_timeStamps.len - 1]);

    // Initialize the view port to show the latest 20% of the time range
    viewer->setViewPortWidth(0.2);
    viewer->setViewPortLeft(1 - viewer->getViewPortWidth());

    // Enable mouse wheel zooming by setting the zoom ratio to 1.1 per wheel event
    viewer->setMouseWheelZoomRatio(1.1);

    // Set the maximum zoom to 10 points
    viewer->setZoomInWidthLimit(10.0 / m_timeStamps.len);
}

//
// The ViewPortChanged event handler. This event occurs if the user scrolls or zooms in
// or out the chart by dragging or clicking on the chart. It can also be triggered by
// calling WinChartViewer.updateViewPort.
//
void ZoomScrollTrack::onViewPortChanged()
{
    // In addition to updating the chart, we may also need to update other controls that
    // changes based on the view port.
    updateControls(m_ChartViewer);

    // Update chart if necessary
    if (m_ChartViewer->needUpdateChart())
        drawChart(m_ChartViewer);
}

//
// Update controls in the user interface when the view port changed
//
void ZoomScrollTrack::updateControls(QChartViewer *viewer)
{
    // The logical length of the scrollbar. It can be any large value. The actual value does
    // not matter.
    const int scrollBarLen = 1000000000;

    // Update the horizontal scroll bar
    m_HScrollBar->setEnabled(viewer->getViewPortWidth() < 1);
    m_HScrollBar->setPageStep((int)ceil(viewer->getViewPortWidth() * scrollBarLen));
    m_HScrollBar->setSingleStep((std::min)(scrollBarLen / 100, m_HScrollBar->pageStep()));
    m_HScrollBar->setRange(0, scrollBarLen - m_HScrollBar->pageStep());
    m_HScrollBar->setValue((int)(0.5 + viewer->getViewPortLeft() * scrollBarLen));
}

//
// Draw the chart and display it in the given viewer
//
void ZoomScrollTrack::drawChart(QChartViewer *viewer)
{
    // Get the start date and end date that are visible on the chart.
    double viewPortStartDate = viewer->getValueAtViewPort("x", viewer->getViewPortLeft());
    double viewPortEndDate = viewer->getValueAtViewPort("x", viewer->getViewPortLeft() +
        viewer->getViewPortWidth());

    // Get the array indexes that corresponds to the visible start and end dates
    int startIndex = (int)floor(Chart::bSearch(m_timeStamps, viewPortStartDate));
    int endIndex = (int)ceil(Chart::bSearch(m_timeStamps, viewPortEndDate));
    int noOfPoints = endIndex - startIndex + 1;

    // Extract the part of the data array that are visible.
    DoubleArray viewPortTimeStamps = DoubleArray(m_timeStamps.data + startIndex, noOfPoints);
    DoubleArray viewPortDataSeriesA = DoubleArray(m_dataSeriesA.data + startIndex, noOfPoints);
    DoubleArray viewPortDataSeriesB = DoubleArray(m_dataSeriesB.data + startIndex, noOfPoints);
    DoubleArray viewPortDataSeriesC = DoubleArray(m_dataSeriesC.data + startIndex, noOfPoints);

    //
    // At this stage, we have extracted the visible data. We can use those data to plot the chart.
    //

    ///////////////////////////////////////////////////////////////////////////////////////
    // Configure overall chart appearance.
    ///////////////////////////////////////////////////////////////////////////////////////

    // Create an XYChart object of size 650 x 350 pixels, with a white (ffffff) background and grey
    // (aaaaaa) border
    XYChart *c = new XYChart(650, 350, 0xffffff, 0xaaaaaa);

    // Set the plotarea at (55, 55) with width 90 pixels less than chart width, and height 90 pixels
    // less than chart height. Use a vertical gradient from light blue (f0f6ff) to sky blue (a0c0ff)
    // as background. Set border to transparent and grid lines to white (ffffff).
    c->setPlotArea(55, 55, c->getWidth() - 90, c->getHeight() - 90, c->linearGradientColor(0, 55, 0,
        c->getHeight() - 35, 0xf0f6ff, 0xa0c0ff), -1, Chart::Transparent, 0xffffff, 0xffffff);

    // As the data can lie outside the plotarea in a zoomed chart, we need enable clipping.
    c->setClipping();

    // Add a title to the chart using 18 pts Times New Roman Bold Italic font
    c->addTitle("   Zooming and Scrolling with Track Line (1)", "Times New Roman Bold Italic", 18);

    // Set legend icon style to use line style icon, sized for 8pt font
    c->getLegend()->setLineStyleKey();
    c->getLegend()->setFontSize(8);

    // Set the axis stem to transparent
    c->xAxis()->setColors(Chart::Transparent);
    c->yAxis()->setColors(Chart::Transparent);

    // Add axis title using 10pts Arial Bold Italic font
    c->yAxis()->setTitle("Ionic Temperature (C)", "Arial Bold Italic", 10);

    ///////////////////////////////////////////////////////////////////////////////////////
    // Add data to chart
    ///////////////////////////////////////////////////////////////////////////////////////

    //
    // In this example, we represent the data by lines. You may modify the code below to use other
    // representations (areas, scatter plot, etc).
    //

    // Add a line layer for the lines, using a line width of 2 pixels
    LineLayer *layer = c->addLineLayer();
    layer->setLineWidth(2);

    // In this demo, we do not have too many data points. In real code, the chart may contain a lot
    // of data points when fully zoomed out - much more than the number of horizontal pixels in this
    // plot area. So it is a good idea to use fast line mode.
    layer->setFastLineMode();

    // Now we add the 3 data series to a line layer, using the color red (ff0000), green
    // (00cc00) and blue (0000ff)
    layer->setXData(viewPortTimeStamps);
    layer->addDataSet(viewPortDataSeriesA, 0xff3333, "Alpha");
    layer->addDataSet(viewPortDataSeriesB, 0x008800, "Beta");
    layer->addDataSet(viewPortDataSeriesC, 0x3333CC, "Gamma");

    ///////////////////////////////////////////////////////////////////////////////////////
    // Configure axis scale and labelling
    ///////////////////////////////////////////////////////////////////////////////////////

    // Set the x-axis as a date/time axis with the scale according to the view port x range.
    viewer->syncDateAxisWithViewPort("x", c->xAxis());

    //
    // In this demo, the time range can be from a few years to a few days. We demonstrate how to set
    // up different date/time format based on the time range.
    //

    // If all ticks are yearly aligned, then we use "yyyy" as the label format.
    c->xAxis()->setFormatCondition("align", 360 * 86400);
    c->xAxis()->setLabelFormat("{value|yyyy}");

    // If all ticks are monthly aligned, then we use "mmm yyyy" in bold font as the first
    // label of a year, and "mmm" for other labels.
    c->xAxis()->setFormatCondition("align", 30 * 86400);
    c->xAxis()->setMultiFormat(Chart::StartOfYearFilter(), "<*font=bold*>{value|mmm yyyy}",
        Chart::AllPassFilter(), "{value|mmm}");

    // If all ticks are daily algined, then we use "mmm dd<*br*>yyyy" in bold font as the
    // first label of a year, and "mmm dd" in bold font as the first label of a month, and
    // "dd" for other labels.
    c->xAxis()->setFormatCondition("align", 86400);
    c->xAxis()->setMultiFormat(Chart::StartOfYearFilter(),
        "<*block,halign=left*><*font=bold*>{value|mmm dd<*br*>yyyy}",
        Chart::StartOfMonthFilter(), "<*font=bold*>{value|mmm dd}");
    c->xAxis()->setMultiFormat(Chart::AllPassFilter(), "{value|dd}");

    // For all other cases (sub-daily ticks), use "hh:nn<*br*>mmm dd" for the first label of
    // a day, and "hh:nn" for other labels.
    c->xAxis()->setFormatCondition("else");
    c->xAxis()->setMultiFormat(Chart::StartOfDayFilter(),
        "<*font=bold*>{value|hh:nn<*br*>mmm dd}", Chart::AllPassFilter(), "{value|hh:nn}");

    ///////////////////////////////////////////////////////////////////////////////////////
    // Output the chart
    ///////////////////////////////////////////////////////////////////////////////////////

    // We need to update the track line too. If the mouse is moving on the chart (eg. if 
    // the user drags the mouse on the chart to scroll it), the track line will be updated
    // in the MouseMovePlotArea event. Otherwise, we need to update the track line here.
    if (!viewer->isInMouseMoveEvent()) 
    {
        trackLineLegend(c, (0 == viewer->getChart()) ? c->getPlotArea()->getRightX() :
            viewer->getPlotAreaMouseX()); 
    }

    delete viewer->getChart();
    viewer->setChart(c);
}

//
// The Pointer, Zoom In or Zoom out button is pressed
//
void ZoomScrollTrack::onMouseUsageChanged(QAbstractButton *b)
{
    m_ChartViewer->setMouseUsage(mouseUsage->id(b));
}

//
// User clicks on the the horizontal scroll bar
//
void ZoomScrollTrack::onHScrollBarChanged(int value)
{
    if (!m_ChartViewer->isInViewPortChangedEvent())
    {
        // Set the view port based on the scroll bar
        int scrollBarLen = m_HScrollBar->maximum() + m_HScrollBar->pageStep();
        m_ChartViewer->setViewPortLeft(value / (double)scrollBarLen);

        // Update the chart display without updating the image maps. (We can delay updating
        // the image map until scrolling is completed and the chart display is stable.)
        m_ChartViewer->updateViewPort(true, false);
    }
}

//
// Draw track cursor when mouse is moving over plotarea
//
void ZoomScrollTrack::onMouseMovePlotArea(QMouseEvent *)
{
    trackLineLegend((XYChart *)m_ChartViewer->getChart(), m_ChartViewer->getPlotAreaMouseX());
    m_ChartViewer->updateDisplay();
}

//
// Draw track line with data labels
//
void ZoomScrollTrack::trackLineLegend(XYChart *c, int mouseX)
{
    // Clear the current dynamic layer and get the DrawArea object to draw on it.
    DrawArea *d = c->initDynamicLayer();

    // The plot area object
    PlotArea *plotArea = c->getPlotArea();

    // Get the data x-value that is nearest to the mouse, and find its pixel coordinate.
    double xValue = c->getNearestXValue(mouseX);
    int xCoor = c->getXCoor(xValue);

    // Draw a vertical track line at the x-position
    d->vline(plotArea->getTopY(), plotArea->getBottomY(), xCoor, d->dashLineColor(0x000000, 0x0101));

    // Container to hold the legend entries
    std::vector<std::string> legendEntries;

    // Iterate through all layers to build the legend array
    for (int i = 0; i < c->getLayerCount(); ++i) {
        Layer *layer = c->getLayerByZ(i);

        // The data array index of the x-value
        int xIndex = layer->getXIndexOf(xValue);

        // Iterate through all the data sets in the layer
        for (int j = 0; j < layer->getDataSetCount(); ++j) {
            DataSet *dataSet = layer->getDataSetByZ(j);

            // We are only interested in visible data sets with names
            const char *dataName = dataSet->getDataName();
            int color = dataSet->getDataColor();
            if (dataName && *dataName && (color != (int)Chart::Transparent)) {
                // Build the legend entry, consist of the legend icon, name and data value.
                double dataValue = dataSet->getValue(xIndex);
                std::ostringstream legendEntry;
                legendEntry << "<*block*>" << dataSet->getLegendIcon() << " " << dataName << ": " <<
                    ((dataValue == Chart::NoValue) ? "N/A" : c->formatValue(dataValue, "{value|P4}"))
                    << "<*/*>";
                legendEntries.push_back(legendEntry.str());

                // Draw a track dot for data points within the plot area
                int yCoor = c->getYCoor(dataSet->getPosition(xIndex), dataSet->getUseYAxis());
                if ((yCoor >= plotArea->getTopY()) && (yCoor <= plotArea->getBottomY())) {
                    d->circle(xCoor, yCoor, 4, 4, color, color);
                }
            }
        }
    }

    // Create the legend by joining the legend entries
    std::ostringstream legendText;
    legendText << "<*block,maxWidth=" << plotArea->getWidth() << "*><*block*><*font=Arial Bold*>["
        << c->xAxis()->getFormattedLabel(xValue, "mmm dd, yyyy") << "]<*/*>";
    for (int i = ((int)legendEntries.size()) - 1; i >= 0; --i)
        legendText << "        " << legendEntries[i];

    // Display the legend on the top of the plot area
    TTFText *t = d->text(legendText.str().c_str(), "Arial", 8);
    t->draw(plotArea->getLeftX() + 5, plotArea->getTopY() - 3, 0x000000, Chart::BottomLeft);
    t->destroy();
}

[QML/Qt Quick version] qmldemo/zoomscrolltrack.qml

import QtQuick
import QtQuick.Window
import QtQuick.Controls
import advsofteng.com 1.0

Window {
    title: "Zooming and Scrolling with Track Line (1)"
    visible: true
    modality: Qt.ApplicationModal
    width: 780
    minimumWidth: 780
    maximumWidth: 780
    height: 380
    minimumHeight: 380
    maximumHeight: 380

    Pane {
        id: leftPane
        width: 120
        padding: 5
        anchors.top: parent.top;
        anchors.bottom: parent.bottom;

        Column {
            Button {
                width: 110
                contentItem: Row {
                    padding: 2; leftPadding: 5
                    Image { source: "icons/scroll_icon.png"; width:16; height:16; }
                    Text { text: "  Pointer"; font.pixelSize: 13; }
                }
                checked: viewer.mouseUsage == QmlChartViewer.MouseUsageScroll
                onClicked: viewer.mouseUsage = QmlChartViewer.MouseUsageScroll
            }
            Button
            {
                width: 110
                contentItem: Row {
                    padding: 2; leftPadding: 5;
                    Image { source: "icons/zoomin_icon.png"; width:16; height:16; }
                    Text { text: "  Zoom In"; font.pixelSize: 13; }
                }
                checked: viewer.mouseUsage == QmlChartViewer.MouseUsageZoomIn
                onClicked: viewer.mouseUsage = QmlChartViewer.MouseUsageZoomIn
            }
            Button {
                width: 110
                contentItem: Row {
                    padding: 2; leftPadding: 5
                    Image { source: "icons/zoomout_icon.png"; width:16; height:16; }
                    Text { text: "  Zoom Out"; font.pixelSize: 13; }
                }
                checked: viewer.mouseUsage == QmlChartViewer.MouseUsageZoomOut
                onClicked: viewer.mouseUsage = QmlChartViewer.MouseUsageZoomOut
            }
        }
    }

    QmlChartViewer
    {
        id: viewer
        anchors.left: leftPane.right
        anchors.leftMargin: 5
        y: 5
        // set default mouse usage to scroll and mouse wheel to zoom
        mouseUsage: QmlChartViewer.MouseUsageScroll
        mouseWheelZoomRatio: 1.1
        // Update track cursor on mouse move
        onMouseMovePlotArea: demo.drawTrackCursor(this, chartMouseX);
        // Update chart on viewport change. Update the scrollbar too.
        onViewPortChanged: {
            if (needUpdateChart)
                demo.drawChart(this);

            hScrollBar.size = Math.min(viewer.viewPortWidth, 0.999999999);
            hScrollBar.position = viewer.viewPortLeft;
        }
    }

    // Add scrollbar under the chart viewer
    ScrollBar
    {
        id: hScrollBar
        orientation: Qt.Horizontal
        height: 20
        anchors.bottom: parent.bottom
        anchors.left: viewer.left
        anchors.right: viewer.right

        onPositionChanged: {
            // The scrollbar and viewport can update each others. To avoid
            // infinite loop, the scrollbar will update the viewport only
            // if the viewport is not updating the scrollbar.
            if (!viewer.isInViewPortChangedEvent) {
                // update the viewport
                viewer.viewPortLeft = this.position;
                viewer.updateViewPort(true, false);
            }
        }
    }

    // The backend implementation of this demo.
    ZoomScrollTrackDemo {
        id: demo;
    }

    Component.onCompleted: {
        demo.initChartViewer(viewer);
        viewer.updateViewPort(true, true);
    }
}

[QML/Qt Quick version] qmldemo/zoomscrolltrack.cpp

#include "zoomscrolltrack.h"
#include <sstream>
#include <math.h>


ZoomScrollTrack::ZoomScrollTrack(QObject *parent) : QObject(parent)
{
    m_currentChart = 0;

    // Load the data
    loadData();
}

ZoomScrollTrack::~ZoomScrollTrack()
{
    delete m_ranSeries;
    delete m_currentChart;
}

//
// Load the data
//
void ZoomScrollTrack::loadData()
{
    // In this example, we just use random numbers as data.
    m_ranSeries = new RanSeries(127);
    m_timeStamps = m_ranSeries->getDateSeries(1827, Chart::chartTime(2007, 1, 1), 86400);
    m_dataSeriesA = m_ranSeries->getSeries(1827, 150, -10, 10);
    m_dataSeriesB = m_ranSeries->getSeries(1827, 200, -10, 10);
    m_dataSeriesC = m_ranSeries->getSeries(1827, 250, -8, 8);
}

//
// Initialize the QChartViewer
//
void ZoomScrollTrack::initChartViewer(QmlChartViewer *viewer)
{
    // Set the full x range to be the duration of the data
    viewer->setFullRange("x", m_timeStamps[0], m_timeStamps[m_timeStamps.len - 1]);

    // Initialize the view port to show the latest 20% of the time range
    viewer->setViewPortWidth(0.2);
    viewer->setViewPortLeft(1 - viewer->getViewPortWidth());

    // Enable mouse wheel zooming by setting the zoom ratio to 1.1 per wheel event
    viewer->setMouseWheelZoomRatio(1.1);

    // Set the maximum zoom to 10 points
    viewer->setZoomInWidthLimit(10.0 / m_timeStamps.len);
}

//
// Draw the chart and display it in the given viewer
//
void ZoomScrollTrack::drawChart(QmlChartViewer *viewer)
{
    // Get the start date and end date that are visible on the chart.
    double viewPortStartDate = viewer->getValueAtViewPort("x", viewer->getViewPortLeft());
    double viewPortEndDate = viewer->getValueAtViewPort("x", viewer->getViewPortLeft() +
        viewer->getViewPortWidth());

    // Get the array indexes that corresponds to the visible start and end dates
    int startIndex = (int)floor(Chart::bSearch(m_timeStamps, viewPortStartDate));
    int endIndex = (int)ceil(Chart::bSearch(m_timeStamps, viewPortEndDate));
    int noOfPoints = endIndex - startIndex + 1;

    // Extract the part of the data array that are visible.
    DoubleArray viewPortTimeStamps = DoubleArray(m_timeStamps.data + startIndex, noOfPoints);
    DoubleArray viewPortDataSeriesA = DoubleArray(m_dataSeriesA.data + startIndex, noOfPoints);
    DoubleArray viewPortDataSeriesB = DoubleArray(m_dataSeriesB.data + startIndex, noOfPoints);
    DoubleArray viewPortDataSeriesC = DoubleArray(m_dataSeriesC.data + startIndex, noOfPoints);

    //
    // At this stage, we have extracted the visible data. We can use those data to plot the chart.
    //

    ///////////////////////////////////////////////////////////////////////////////////////
    // Configure overall chart appearance.
    ///////////////////////////////////////////////////////////////////////////////////////

    // Create an XYChart object of size 650 x 350 pixels, with a white (ffffff) background and grey
    // (aaaaaa) border
    XYChart *c = new XYChart(650, 350, 0xffffff, 0xaaaaaa);

    // Set the plotarea at (55, 55) with width 90 pixels less than chart width, and height 90 pixels
    // less than chart height. Use a vertical gradient from light blue (f0f6ff) to sky blue (a0c0ff)
    // as background. Set border to transparent and grid lines to white (ffffff).
    c->setPlotArea(55, 55, c->getWidth() - 90, c->getHeight() - 90, c->linearGradientColor(0, 55, 0,
        c->getHeight() - 35, 0xf0f6ff, 0xa0c0ff), -1, Chart::Transparent, 0xffffff, 0xffffff);

    // As the data can lie outside the plotarea in a zoomed chart, we need enable clipping.
    c->setClipping();

    // Add a title to the chart using 18 pts Times New Roman Bold Italic font
    c->addTitle("   Zooming and Scrolling with Track Line (1)", "Times New Roman Bold Italic", 18);

    // Set legend icon style to use line style icon, sized for 8pt font
    c->getLegend()->setLineStyleKey();
    c->getLegend()->setFontSize(8);

    // Set the axis stem to transparent
    c->xAxis()->setColors(Chart::Transparent);
    c->yAxis()->setColors(Chart::Transparent);

    // Add axis title using 10pts Arial Bold Italic font
    c->yAxis()->setTitle("Ionic Temperature (C)", "Arial Bold Italic", 10);

    ///////////////////////////////////////////////////////////////////////////////////////
    // Add data to chart
    ///////////////////////////////////////////////////////////////////////////////////////

    //
    // In this example, we represent the data by lines. You may modify the code below to use other
    // representations (areas, scatter plot, etc).
    //

    // Add a line layer for the lines, using a line width of 2 pixels
    LineLayer *layer = c->addLineLayer();
    layer->setLineWidth(2);

    // In this demo, we do not have too many data points. In real code, the chart may contain a lot
    // of data points when fully zoomed out - much more than the number of horizontal pixels in this
    // plot area. So it is a good idea to use fast line mode.
    layer->setFastLineMode();

    // Now we add the 3 data series to a line layer, using the color red (ff0000), green
    // (00cc00) and blue (0000ff)
    layer->setXData(viewPortTimeStamps);
    layer->addDataSet(viewPortDataSeriesA, 0xff3333, "Alpha");
    layer->addDataSet(viewPortDataSeriesB, 0x008800, "Beta");
    layer->addDataSet(viewPortDataSeriesC, 0x3333CC, "Gamma");

    ///////////////////////////////////////////////////////////////////////////////////////
    // Configure axis scale and labelling
    ///////////////////////////////////////////////////////////////////////////////////////

    // Set the x-axis as a date/time axis with the scale according to the view port x range.
    viewer->syncDateAxisWithViewPort("x", c->xAxis());

    //
    // In this demo, the time range can be from a few years to a few days. We demonstrate how to set
    // up different date/time format based on the time range.
    //

    // If all ticks are yearly aligned, then we use "yyyy" as the label format.
    c->xAxis()->setFormatCondition("align", 360 * 86400);
    c->xAxis()->setLabelFormat("{value|yyyy}");

    // If all ticks are monthly aligned, then we use "mmm yyyy" in bold font as the first
    // label of a year, and "mmm" for other labels.
    c->xAxis()->setFormatCondition("align", 30 * 86400);
    c->xAxis()->setMultiFormat(Chart::StartOfYearFilter(), "<*font=bold*>{value|mmm yyyy}",
        Chart::AllPassFilter(), "{value|mmm}");

    // If all ticks are daily algined, then we use "mmm dd<*br*>yyyy" in bold font as the
    // first label of a year, and "mmm dd" in bold font as the first label of a month, and
    // "dd" for other labels.
    c->xAxis()->setFormatCondition("align", 86400);
    c->xAxis()->setMultiFormat(Chart::StartOfYearFilter(),
        "<*block,halign=left*><*font=bold*>{value|mmm dd<*br*>yyyy}",
        Chart::StartOfMonthFilter(), "<*font=bold*>{value|mmm dd}");
    c->xAxis()->setMultiFormat(Chart::AllPassFilter(), "{value|dd}");

    // For all other cases (sub-daily ticks), use "hh:nn<*br*>mmm dd" for the first label of
    // a day, and "hh:nn" for other labels.
    c->xAxis()->setFormatCondition("else");
    c->xAxis()->setMultiFormat(Chart::StartOfDayFilter(),
        "<*font=bold*>{value|hh:nn<*br*>mmm dd}", Chart::AllPassFilter(), "{value|hh:nn}");

    ///////////////////////////////////////////////////////////////////////////////////////
    // Output the chart
    ///////////////////////////////////////////////////////////////////////////////////////

    // We need to update the track line too. If the mouse is moving on the chart (eg. if
    // the user drags the mouse on the chart to scroll it), the track line will be updated
    // in the MouseMovePlotArea event. Otherwise, we need to update the track line here.
    if (!viewer->isInMouseMoveEvent())
    {
        trackLineLegend(c, (0 == viewer->getChart()) ? c->getPlotArea()->getRightX() :
            viewer->getPlotAreaMouseX());
    }

    delete viewer->getChart();
    viewer->setChart(m_currentChart = c);
}

//
// Draw track cursor when mouse is moving over plotarea
//
void ZoomScrollTrack::drawTrackCursor(QmlChartViewer *viewer, int mouseX)
{
    trackLineLegend((XYChart *)viewer->getChart(), mouseX);
    viewer->updateDisplay();
}

//
// Draw track line with data labels
//
void ZoomScrollTrack::trackLineLegend(XYChart *c, int mouseX)
{
    // Clear the current dynamic layer and get the DrawArea object to draw on it.
    DrawArea *d = c->initDynamicLayer();

    // The plot area object
    PlotArea *plotArea = c->getPlotArea();

    // Get the data x-value that is nearest to the mouse, and find its pixel coordinate.
    double xValue = c->getNearestXValue(mouseX);
    int xCoor = c->getXCoor(xValue);

    // Draw a vertical track line at the x-position
    d->vline(plotArea->getTopY(), plotArea->getBottomY(), xCoor, d->dashLineColor(0x000000, 0x0101));

    // Container to hold the legend entries
    std::vector<std::string> legendEntries;

    // Iterate through all layers to build the legend array
    for (int i = 0; i < c->getLayerCount(); ++i) {
        Layer *layer = c->getLayerByZ(i);

        // The data array index of the x-value
        int xIndex = layer->getXIndexOf(xValue);

        // Iterate through all the data sets in the layer
        for (int j = 0; j < layer->getDataSetCount(); ++j) {
            DataSet *dataSet = layer->getDataSetByZ(j);

            // We are only interested in visible data sets with names
            const char *dataName = dataSet->getDataName();
            int color = dataSet->getDataColor();
            if (dataName && *dataName && (color != (int)Chart::Transparent)) {
                // Build the legend entry, consist of the legend icon, name and data value.
                double dataValue = dataSet->getValue(xIndex);
                std::ostringstream legendEntry;
                legendEntry << "<*block*>" << dataSet->getLegendIcon() << " " << dataName << ": " <<
                    ((dataValue == Chart::NoValue) ? "N/A" : c->formatValue(dataValue, "{value|P4}"))
                    << "<*/*>";
                legendEntries.push_back(legendEntry.str());

                // Draw a track dot for data points within the plot area
                int yCoor = c->getYCoor(dataSet->getPosition(xIndex), dataSet->getUseYAxis());
                if ((yCoor >= plotArea->getTopY()) && (yCoor <= plotArea->getBottomY())) {
                    d->circle(xCoor, yCoor, 4, 4, color, color);
                }
            }
        }
    }

    // Create the legend by joining the legend entries
    std::ostringstream legendText;
    legendText << "<*block,maxWidth=" << plotArea->getWidth() << "*><*block*><*font=Arial Bold*>["
        << c->xAxis()->getFormattedLabel(xValue, "mmm dd, yyyy") << "]<*/*>";
    for (int i = ((int)legendEntries.size()) - 1; i >= 0; --i)
        legendText << "        " << legendEntries[i];

    // Display the legend on the top of the plot area
    TTFText *t = d->text(legendText.str().c_str(), "Arial", 8);
    t->draw(plotArea->getLeftX() + 5, plotArea->getTopY() - 3, 0x000000, Chart::BottomLeft);
    t->destroy();
}