ChartDirector 6.1 (Java Edition)

Track Line with Vertical Legend (Web)

This sample program demonstrates a track cursor programmed with the following features:

On the server side, the code draws the chart as usual, and outputs both the image and the Javascript Chart Model of the chart.

On the browser side, in the window onload event handler, Javascript is used to set up the event handler for the MouseMovePlotArea, TouchStartPlotArea, TouchMovePlotArea and ChartMove events. The event handler calls trackVLegend to draw the track cursor. It also calls JsChartViewer.setAutoHide to automatically hide the track cursor when the MouseOutPlotArea or TouchEndPlotArea event occurs.

The trackVLegend Javascript function is the routine that draws the track cursor. Its key elements are:

Source Code Listing

[JSP Version] jspdemo/trackvlegend.jsp
<%@page import="ChartDirector.*" %>
<%@page import="java.util.*" %>
// In this example, we simply use random data for the 2 data series.
RanSeries r = new RanSeries(127);
double[] data0 = r.getSeries(180, 70, -5, 5);
double[] data1 = r.getSeries(180, 150, -15, 15);
Date[] timeStamps = r.getDateSeries(180, new GregorianCalendar(2014, 2, 1).getTime(), 86400);

// Create a XYChart object of size 640 x 420 pixels
XYChart c = new XYChart(640, 420);

// Add a title to the chart using 20pt Arial font
c.addTitle("    Plasma Stabilizer Energy Usage", "Arial", 20);

// Set the plotarea at (55, 60) and of size 560 x 330 pixels, with transparent background and border
// and light grey (0xcccccc) horizontal grid lines
c.setPlotArea(55, 60, 560, 330, -1, -1, Chart.Transparent, 0xcccccc);

// Add a legend box at (55, 30) using horizontal layout, with 10pt Arial Bold as font and
// transparent background and border.
c.addLegend(55, 30, false, "Arial Bold", 10).setBackground(Chart.Transparent);

// Set axis label style to 10pt Arial
c.xAxis().setLabelStyle("Arial", 10);
c.yAxis().setLabelStyle("Arial", 10);

// Set the x and y axis stems to transparent, and the x-axis tick color to grey (0xcccccc)
c.xAxis().setColors(Chart.Transparent, Chart.TextColor, Chart.TextColor, 0xcccccc);

// Configure the x-axis tick lengtht to 10 pixels internal to the plot area
c.xAxis().setTickLength(-10, 0);

// With the ticks internal to the plot area, the x-axis labels will come very close to the axis
// stem, so we configure a wider gap.

// For the automatic axis labels, set the minimum spacing to 80/40 pixels for the x/y axis.

// Use "mm/yyyy" as the x-axis label format for the first plotted month of a year, and "mm" for
// other months
c.xAxis().setMultiFormat(Chart.StartOfYearFilter(), "{value|mm/yyyy} ", Chart.StartOfMonthFilter(),

// Add a title to the y axis using dark grey (0x555555) 12pt Arial Bold font
c.yAxis().setTitle("Energy (kWh)", "Arial Bold", 14, 0x555555);

// Add a line layer with 2-pixel line width
LineLayer layer0 = c.addLineLayer(data0, 0xcc0000, "Power Usage");

// Add an area layer using semi-transparent blue (0x7f0044cc) as the fill color
AreaLayer layer1 = c.addAreaLayer(data1, 0x7f0044cc, "Effective Load");

// Create the WebChartViewer object
WebChartViewer viewer = new WebChartViewer(request, "chart1");

// Output the chart
String chartQuery = c.makeSession(viewer.getRequest(), viewer.getId());

// Set the chart URL to the viewer
viewer.setImageUrl("getchart.jsp?" + chartQuery);

// Output Javascript chart model to the browser to support tracking cursor

<!DOCTYPE html>
    <title>Track Line with Vertical Legend</title>
    <script type="text/javascript" src="cdjcv.js"></script>
    .legend {border:solid 1px #888888; black;background:#eeeeee; font:13px Arial; padding:2px;
             border-radius:4px; white-space:nowrap;-webkit-text-size-adjust:100%;}
    .legend_caption {text-decoration:underline; font-weight:bold; padding-bottom:2px;}
    .legend_table {border-spacing:0px;}
    .legend_table td {padding:1px 0px 1px 3px;}
    .legend_slide  {-webkit-transition:left 0.3s;}
<body style="margin:5px 0px 0px 5px">
<script type="text/javascript">

// Use the window load event to set up the MouseMovePlotArea event handler
JsChartViewer.addEventListener(window, 'load', function() {
    var viewer = JsChartViewer.get('<%=viewer.getId()%>');

    // Draw track cursor when mouse is moving over plotarea. Hide it when mouse leaves plot area.
    viewer.attachHandler(["MouseMovePlotArea", "TouchStartPlotArea", "TouchMovePlotArea", "ChartMove"],
    function(e) {
        this.preventDefault(e);   // Prevent the browser from using touch events for other actions
        trackVLegend(viewer, viewer.getPlotAreaMouseX());
        viewer.setAutoHide("all", ["MouseOutPlotArea", "TouchEndPlotArea"]);

// Draw track line with axis labels
function trackVLegend(viewer, mouseX)
    // Remember whether we are displaying the legend initially or updating the display.
    var legendIsVisible = viewer.isVisible("legend");

    // Remove all previously drawn tracking object

    // The chart and its plot area
    var c = viewer.getChart();
    var plotArea = c.getPlotArea();

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

    // Draw a vertical track line at the x-position
    viewer.drawVLine("trackLine", xCoor, plotArea.getTopY(), plotArea.getBottomY(), "black 1px dotted");

    // Array to hold the legend entries
    var legendEntries = [];

    // Iterate through all layers to draw the axis labels for the data points
    for (var i = 0; i < c.getLayerCount(); ++i)
      var layer = c.getLayerByZ(i);

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

        // Iterate through all the data sets in the layer
        for (var j = 0; j < layer.getDataSetCount(); ++j)
            var dataSet = layer.getDataSetByZ(j);

            // Only visible data sets with names are included in the legend.
            var dataName = dataSet.getDataName();
            var color = dataSet.getDataColor();
            var dataValue = dataSet.getValue(xIndex);
            if ((!dataName) || (color == null) || (dataValue == null))

            // Build the legend entry, consist of a colored square box, the name and the data value.
            legendEntries.push("<tr><td>" + viewer.htmlRect(7, 7, color, "black 1px solid") + " " +
                dataSet.getDataName() + ":</td><td>" + dataValue.toPrecision(4) + "</td></tr>");

            // Draw a track dot for data points within the plot area
            var yCoor = c.getYCoor(dataSet.getPosition(xIndex));
            if ((yCoor != null) && (yCoor >= plotArea.getTopY()) && (yCoor <= plotArea.getBottomY()))
                   viewer.showTextBox("dataPoint" + i + "_" + j, xCoor, yCoor, JsChartViewer.Center,
                       viewer.htmlRect(7, 7, color, "black 1px solid"));

    if (legendEntries.length > 0)
        // Create the legend by joining the legend entries
        var legend = "<div class='legend_caption'>" + c.xAxis().getFormattedLabel(xValue, "yyyy-mm-dd")
            + "</div><table class='legend_table'>" + legendEntries.reverse().join("") + "</table>";

        // Put the legend box at the opposite side of the mouse
        var mouseOnRight = xCoor >= (plotArea.getLeftX() + plotArea.getRightX()) / 2;
        var legendX = mouseOnRight ? (plotArea.getLeftX() + 1) : (plotArea.getRightX() - 1);
        var alignment = mouseOnRight ? JsChartViewer.TopLeft : JsChartViewer.TopRight;

        var legendStyle = "class:legend" + (legendIsVisible ? " legend_slide" : "") + ";";
        var legendBox = viewer.showClickableTextBox("legend", legendX, plotArea.getTopY(),
            alignment, legend, legendStyle);

<div style="font-size:18pt; font-family:verdana; font-weight:bold">
    Track Line with Vertical Legend
<hr style="border:solid 1px #000080" />
<div style="font-size:10pt; font-family:verdana; margin-bottom:1.5em">
    <a href="viewsource.jsp?file=<%=request.getServletPath()%>">View Source Code</a>
<!-- ****** Here is the chart image ****** -->