Finance Chart Track Line

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

A vertical line that follows the mouse cursor on the plot area and snaps to the nearest trading session.
Dynamically updated legend entries that shows the price, volume and other technical indicator for the nearest trading session.

On the server side, the code draws the finance chart with the legend box set to transparent (so that the default legend box is not displayed), It 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 , ChartMove and Now events. The event handler calls trackFinance to draw the track cursor.

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

The code first uses JsChartViewer.hideObj to clear the previous track cursor, if any.
The nearest trading session is obtained from the first JsXYChart in the FinanceChart using JsXYChart.getNearestXValue.
The code iterates through all the JsXYChart objects in the FinanceChart. For each JsXYChart, the code iterates through all the layers to create dynamic legend entries. The FinanceChart creates default static legend entries for all indicators showing their latest values (even though the default static legend box is set to transparent in the chart). The code creates the dynamic legend entries by replacing the values in the static legend entries.
If a layer contains 4 data sets, the code assumes it is either a CandleStickLayer or HLOCLayer. It formats a legend entry consisting of the open, high, low, close values, as well as an up/down icon and the percentage change.
If a layer contains 2 data sets, the code assumes the layer is for a "band" or "channel" (such as Bollinger Band or Donchian Channel). The code formats a legend entry by replacing the values in the default legend entry (obtained using JsDataSet.getDataName).
If a layer contains 3 data sets, the code assumes the layer is for volume bars, with the 3 data sets representing volume bars of different colors for up, down and flat days. The code computes the volume by adding the values from the three data sets, and formats a legend entry by replacing the value in the default legend entry (obtained using JsDataSet.getDataName) with the computed value.
In all other cases, the code iterates the data sets. For each of them, it formats a legend by replacing the value in the default legend entry (obtained using JsDataSet.getDataName) with the value for the nearest trading session (obtained using JsDataSet.getValue).
Finally, the code combines all the legend entries into a legend box and draws it on top of the plot area using JsChartViewer.showTextBox. It also draws a vertical line at the nearest trading session using JsChartViewer.drawVLine.

[Web Version (in ASP)] aspdemo\trackfinance.asp

<%@ language="vbscript" %>
<%
Set cd = CreateObject("ChartDirector.API")

' Create a finance chart demo containing 100 days of data
noOfDays = 100

' To compute moving averages starting from the first day, we need to get extra data points before
' the first day
extraDays = 30

' In this exammple, we use a random number generator utility to simulate the data. We set up the
' random table to create 6 cols x (noOfDays + extraDays) rows, using 9 as the seed.
Set rantable = cd.RanTable(9, 6, noOfDays + extraDays)

' Set the 1st col to be the timeStamp, starting from Sep 4, 2011, with each row representing one
' day, and counting week days only (jump over Sat and Sun)
Call rantable.setDateCol(0, DateSerial(2011, 9, 4), 86400, True)

' Set the 2nd, 3rd, 4th and 5th columns to be high, low, open and close data. The open value starts
' from 100, and the daily change is random from -5 to 5.
Call rantable.setHLOCCols(1, 100, -5, 5)

' Set the 6th column as the vol data from 5 to 25 million
Call rantable.setCol(5, 50000000, 250000000)

' Now we read the data from the table into arrays
timeStamps = rantable.getCol(0)
highData = rantable.getCol(1)
lowData = rantable.getCol(2)
openData = rantable.getCol(3)
closeData = rantable.getCol(4)
volData = rantable.getCol(5)

' Create a FinanceChart object of width 720 pixels
Set c = cd.FinanceChart(720)

' Add a title to the chart
Call c.addTitle("Finance Chart Demonstration")

' Disable default legend box, as we are using dynamic legend
Call c.setLegendStyle("normal", 8, cd.Transparent, cd.Transparent)

' Set the data into the finance chart object
Call c.setData(timeStamps, highData, lowData, openData, closeData, volData, extraDays)

' Add the main chart with 240 pixels in height
Call c.addMainChart(240)

' Add a 10 period simple moving average to the main chart, using brown color
Call c.addSimpleMovingAvg(10, &H663300)

' Add a 20 period simple moving average to the main chart, using purple color
Call c.addSimpleMovingAvg(20, &H9900ff)

' Add candlestick symbols to the main chart, using green/red for up/down days
Call c.addCandleStick(&H00ff00, &Hff0000)

' Add 20 days bollinger band to the main chart, using light blue (9999ff) as the border and
' semi-transparent blue (c06666ff) as the fill color
Call c.addBollingerBand(20, 2, &H9999ff, &Hc06666ff)

' Add a 75 pixels volume bars sub-chart to the bottom of the main chart, using green/red/grey for
' up/down/flat days
Call c.addVolBars(75, &H99ff99, &Hff9999, &H808080)

' Append a 14-days RSI indicator chart (75 pixels high) after the main chart. The main RSI line is
' purple (800080). Set threshold region to +/- 20 (that is, RSI = 50 +/- 25). The upper/lower
' threshold regions will be filled with red (ff0000)/blue (0000ff).
Call c.addRSI(75, 14, &H800080, 20, &Hff0000, &H0000ff)

' Append a MACD(26, 12) indicator chart (75 pixels high) after the main chart, using 9 days for
' computing divergence.
Call c.addMACD(75, 26, 12, 9, &H0000ff, &Hff00ff, &H008000)

' Create the WebChartViewer object
Set viewer = cd.WebChartViewer(Request, "chart1")

' Output the chart
Call viewer.setChart(c, cd.SVG)

' Output Javascript chart model to the browser to support tracking cursor
viewer.ChartModel = c.getJsChartModel()
%>

<!DOCTYPE html>
<html>
<head>
    <title>Finance Chart Track Line</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.Id%>');

    // Draw track cursor when mouse is moving over plotarea
    viewer.attachHandler(["MouseMovePlotArea", "TouchStartPlotArea", "TouchMovePlotArea", "ChartMove", "Now"],
    function(e) {
        this.preventDefault(e);   // Prevent the browser from using touch events for other actions
        traceFinance(viewer, viewer.getPlotAreaMouseX());
    });
});

//
// Draw finance chart track line with legend
//
function traceFinance(viewer, mouseX)
{
    // Remove all previously drawn tracking object
    viewer.hideObj("all");

    // It is possible for a FinanceChart to be empty, so we need to check for it.
    if (!viewer.getChart())
        return;

    // Get the data x-value that is nearest to the mouse
    var xValue = viewer.getChart().getNearestXValue(mouseX);

    // Iterate the XY charts (main price chart and indicator charts) in the FinanceChart
    var c = null;
    for (var i = 0; i < viewer.getChartCount(); ++i)
    {
        c = viewer.getChart(i);

        // Variables to hold the legend entries
        var ohlcLegend = "";
        var legendEntries = [];

        // Iterate through all layers to build the legend array
        for (var j = 0; j < c.getLayerCount(); ++j)
        {
            var layer = c.getLayerByZ(j);
            var xIndex = layer.getXIndexOf(xValue);
            var dataSetCount = layer.getDataSetCount();

            // In a FinanceChart, only layers showing OHLC data can have 4 data sets
            if (dataSetCount == 4)
            {
                var highValue = layer.getDataSet(0).getValue(xIndex);
                var lowValue = layer.getDataSet(1).getValue(xIndex);
                var openValue = layer.getDataSet(2).getValue(xIndex);
                var closeValue = layer.getDataSet(3).getValue(xIndex);

                if (closeValue == null)
                    continue;

                // Build the OHLC legend
                ohlcLegend =
                    "Open: " + openValue.toPrecision(4) + ", High: " + highValue.toPrecision(4) +
                    ", Low: " + lowValue.toPrecision(4) + ", Close: " + closeValue.toPrecision(4);

                // We also draw an upward or downward triangle for up and down days and the % change
                var lastCloseValue = layer.getDataSet(3).getValue(xIndex - 1);
                if (lastCloseValue != null)
                {
                    var change = closeValue - lastCloseValue;
                    var percent = change * 100 / closeValue;
                    if (change >= 0)
                        ohlcLegend += "&nbsp;&nbsp;<span style='color:#008800;'>&#9650; ";
                    else
                        ohlcLegend += "&nbsp;&nbsp;<span style='color:#CC0000;'>&#9660; ";
                    ohlcLegend += change.toPrecision(4) + " (" + percent.toFixed(2) + "%)</span>";
                }

                // Add a spacer box, and make sure the line does not wrap within the legend entry
                ohlcLegend = "<nobr>" + ohlcLegend + viewer.htmlRect(20, 0) + "</nobr> ";
            }
            else
            {
                // Iterate through all the data sets in the layer
                for (var k = 0; k < dataSetCount; ++k)
                {
                    var dataSet = layer.getDataSetByZ(k);
                    var name = dataSet.getDataName();
                    var value = dataSet.getValue(xIndex);
                    if ((!name) || (value == null))
                        continue;

                    // In a FinanceChart, the data set name consists of the indicator name and its latest value. It is
                    // like "Vol: 123M" or "RSI (14): 55.34". As we are generating the values dynamically, we need to
                    // extract the indictor name out, and also the volume unit (if any).

                    // The unit character, if any, is the last character and must not be a digit.
                    var unitChar = name.charAt(name.length - 1);
                    if ((unitChar >= '0') && (unitChar <= '9'))
                        unitChar = '';

                    // The indicator name is the part of the name up to the colon character.
                    var delimiterPosition = name.indexOf(':');
                    if (delimiterPosition != -1)
                        name = name.substring(0, delimiterPosition);

                    // In a FinanceChart, if there are two data sets, it must be representing a range.
                    if (dataSetCount == 2)
                    {
                        // We show both values in the range
                        var value2 = layer.getDataSetByZ(1 - k).getValue(xIndex);
                        name = name + ": " + Math.min(value, value2).toPrecision(4) + " - "
                            + Math.max(value, value2).toPrecision(4);
                    }
                    else
                    {
                        // In a FinanceChart, only the layer for volume bars has 3 data sets for up/down/flat days
                        if (dataSetCount == 3)
                        {
                            // The actual volume is the sum of the 3 data sets.
                            value = layer.getDataSet(0).getValue(xIndex) + layer.getDataSet(1).getValue(xIndex) +
                                layer.getDataSet(2).getValue(xIndex);
                        }

                        // Create the legend entry
                        name = name + ": " + value.toPrecision(4) + unitChar;
                    }

                    // Build the legend entry, consist of a colored square box and the name (with the data value in it).
                    legendEntries.push("<nobr>" + viewer.htmlRect(5, 5, dataSet.getDataColor(),
                        "solid 1px black") + " " + name + viewer.htmlRect(20, 0) + "</nobr>");
                }
            }
        }

        // The legend is formed by concatenating the legend entries.
        var legend = legendEntries.reverse().join(" ");

        // Add the date and the ohlcLegend (if any) at the beginning of the legend
        legend = "<nobr>[" + c.xAxis().getFormattedLabel(xValue, "mmm dd, yyyy") + "]" + viewer.htmlRect(20, 0) +
            "</nobr> " + ohlcLegend + legend;

        // Get the plot area position relative to the entire FinanceChart
        var plotArea = c.getPlotArea();
        var plotAreaLeftX = plotArea.getLeftX() + c.getAbsOffsetX();
        var plotAreaTopY = plotArea.getTopY() + c.getAbsOffsetY();

        // Draw a vertical track line at the x-position
        viewer.drawVLine("trackLine" + i, c.getXCoor(xValue) + c.getAbsOffsetX(), plotAreaTopY,
            plotAreaTopY + plotArea.getHeight(), "black 1px dotted");

        // Display the legend on the top of the plot area
        viewer.showTextBox("legend" + i, plotAreaLeftX + 1, plotAreaTopY + 1, JsChartViewer.TopLeft, legend,
            "padding-left:5px;width:" + (plotArea.getWidth() - 1) + "px;font:11px Arial;-webkit-text-size-adjust:100%;");
    }
}

</script>
<div style="font-size:18pt; font-family:verdana; font-weight:bold">
    Finance Chart Track Line
</div>
<hr style="border:solid 1px #000080" />
<div style="font-size:10pt; font-family:verdana; margin-bottom:1.5em">
    <a href="viewsource.asp?file=<%=Request("SCRIPT_NAME")%>">View Source Code</a>
</div>
<!-- ****** Here is the chart image ****** -->
<%=viewer.renderHTML()%>
</body>
</html>