ChartDirector 6.1 (Java Edition)

Crosshair with Axis Labels (Web)




NOTE: This section describes Crosshair with Axis Labels for web applications only. For Windows applications, please refer to Crosshair with Axis Labels (Windows).

This sample program demonstrates a track cursor programmed as a crosshair cursor with axis labels. In additional, it demonstrates using hot spot events to pop up a box when the mouse is over a data point or the trend line, showing information about these objects with HTML formatting.

The key elements of the server side charting code are as follows:

Source Code Listing

[JSP Version] jspdemo/crosshair.jsp
<%@page import="ChartDirector.*" %>
<%
// The XY data of the first data series
double[] dataX = {50, 55, 37, 24, 42, 49, 63, 72, 83, 59};
double[] dataY = {3.6, 2.8, 2.5, 2.3, 3.8, 3.0, 3.8, 5.0, 6.0, 3.3};

// Create a XYChart object of size 520 x 490 pixels
XYChart c = new XYChart(520, 490);

// Set the plotarea at (60, 40) and of size 450 x 400 pixels, with white background and a light grey
// border (0xc0c0c0). Turn on both horizontal and vertical grid lines with light grey color
// (0xc0c0c0)
c.setPlotArea(60, 40, 450, 400, 0xffffff, -1, 0xc0c0c0, 0xc0c0c0, -1);

// Add a title to the chart using 18 point Times Bold Itatic font.
c.addTitle("      Chemical X Thermal Conductivity", "Times New Roman Bold Italic", 18);

// Add titles to the axes using 12pt Arial Bold Italic font
c.yAxis().setTitle("Thermal Conductivity (W/K)", "Arial Bold Italic", 12);
c.xAxis().setTitle("Concentration (g/liter)", "Arial Bold Italic", 12);

// Set the axes line width to 3 pixels
c.yAxis().setWidth(3);
c.xAxis().setWidth(3);

// Add a scatter layer using (dataX, dataY)
ScatterLayer scatterLayer = c.addScatterLayer(dataX, dataY, "", Chart.GlassSphereShape, 13, 0xcc0000
    );

// Show custom Javascript tooltip for the scatter layer
scatterLayer.setHTMLImageMap("", "",
    "onmouseover='showDataPointToolTip({x}, {value})' onmouseout='hideToolTip()'");

// Add a trend line layer for (dataX, dataY)
TrendLayer trendLayer = c.addTrendLayer2(dataX, dataY, 0xcc0000);

// Set the line width to 3 pixels
trendLayer.setLineWidth(3);

// Add a 95% confidence band for the line
trendLayer.addConfidenceBand(0.95, 0x806666ff);

// Add a 95% confidence band (prediction band) for the points
trendLayer.addPredictionBand(0.95, 0x8066ff66);

// Show custom Javascript tooltip for the trend layer
trendLayer.setHTMLImageMap("", "",
    "onmouseover='showTrendLineToolTip({slope}, {intercept})' onmouseout='hideToolTip()'");

// Add a legend box at (60, 35) (top of the chart) with horizontal layout. Use 10pt Arial Bold
// Italic font. Set the background and border color to Transparent and use line style legend icons.
LegendBox legendBox = c.addLegend(60, 35, false, "Arial Bold Italic", 9);
legendBox.setBackground(Chart.Transparent);
legendBox.setLineStyleKey(true);

// Add entries to the legend box
legendBox.addKey("95% Line Confidence", 0x806666ff);
legendBox.addKey("95% Point Confidence", 0x8066ff66);
legendBox.addKey(java.text.MessageFormat.format(
    "Trend Line: y = {0,number,#.####} x + {1,number,#.####}", new Object[]{new Double(
    trendLayer.getSlope()), new Double(trendLayer.getIntercept())}), 0xcc0000, 3);

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

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

// Include tool tip for the chart
String imageMap = c.getHTMLImageMap("");

// Set the chart URL and image map to the viewer
viewer.setImageUrl("getchart.jsp?" + chartQuery);
viewer.setImageMap(imageMap);

// Output Javascript chart model to the browser to support tracking cursor
viewer.setChartModel(c.getJsChartModel());
%>
<!DOCTYPE html>
<html>
<head>
    <title>Crosshair with Axis Labels</title>
    <script type="text/javascript" src="cdjcv.js"></script>
</head>
<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
        crossHairAxisLabel(viewer, viewer.getPlotAreaMouseX(), viewer.getPlotAreaMouseY());
        viewer.setAutoHide("all", ["MouseOutPlotArea", "TouchEndPlotArea"]);
    });
});

//
// Draw cross hair cursor with axis labels
//
function crossHairAxisLabel(viewer, x, y)
{
    // Show cross hair
    viewer.showCrossHair(x, y);

    // The chart, its plot area and axes
    var c = viewer.getChart();
    var xAxis = c.xAxis();
    var yAxis = c.yAxis();

    // The axis label style
    var labelStyle = "padding:2px 4px; font: bold 8pt arial; border:1px solid black;" +
        "background-color:#DDDDFF; -webkit-text-size-adjust:100%;";

    // Draw x-axis label
    var yPos = xAxis.getY() + ((xAxis.getAlignment() == JsChartViewer.Top) ? -2 : 3);
    var alignment = (xAxis.getAlignment() == JsChartViewer.Top) ? JsChartViewer.Bottom : JsChartViewer.Top;
    viewer.showTextBox("xAxisLabel", x, yPos, alignment, c.getXValue(x).toPrecision(4), labelStyle);

    // Draw y-axis label
    var xPos = yAxis.getX() + ((yAxis.getAlignment() == JsChartViewer.Left) ? -2 : 3);
    var alignment = (yAxis.getAlignment() == JsChartViewer.Left) ? JsChartViewer.Right : JsChartViewer.Left;
    viewer.showTextBox("yAxisLabel", xPos, y, alignment, c.getYValue(y, yAxis).toPrecision(4), labelStyle);
}

//
// Show custom tooltip for data points
//
function showDataPointToolTip(x, y)
{
    var viewer = JsChartViewer.get('<%=viewer.getId()%>');
    viewer.showTextBox("toolTipBox", viewer.getChartMouseX() + 20, viewer.getChartMouseY() + 20, JsChartViewer.TopLeft,
        "<table><tr><td>Concentration</td><td>: " + x.toPrecision(4) +
        " g/liter</td></tr><tr><td>Conductivity</td><td>: " + y.toPrecision(4) + " W/K</td></tr></table>",
        "padding:0px; font:bold 8pt arial; border:1px solid black; background-color:#DDDDFF");
}

//
// Show custom tooltip for the trend line
//
function showTrendLineToolTip(slope, intercept)
{
    var viewer = JsChartViewer.get('<%=viewer.getId()%>');
    viewer.showTextBox("toolTipBox", viewer.getChartMouseX() + 20, viewer.getChartMouseY() + 20, JsChartViewer.TopLeft,
        "Trend Line: y = " + slope.toFixed(4) + " x + " + intercept.toFixed(4),
        "padding:2px 4px; font:bold 8pt arial; border:1px solid black; background-color:#DDDDFF");
}

//
// Hide custom tooltip
//
function hideToolTip()
{
    var viewer = JsChartViewer.get('<%=viewer.getId()%>');
    viewer.hideObj("toolTipBox");
}

</script>
<div style="font-size:18pt; font-family:verdana; font-weight:bold">
    Crosshair with Axis Labels
</div>
<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>
</div>
<!-- ****** Here is the chart image ****** -->
<%=viewer.renderHTML(response)%>
</body>
</html>