Positive Negative Bars

This example demonstrates a bar chart containing positive and negative data, represented by different colors.

In this example, the two colors of the plot area background are configured using background zones, while the bar colors are configured by splitting the bars into two layers.

Use XYChart.addBarLayer2 with Overlay to add an overlay bar layer to the chart.
Use ArrayMath.selectGEZ to select the data values greater than or equal to zero and use Layer.addDataSet to add them as the blue data set.
Use ArrayMath.selectLTZ to select the data values less than zero and use Layer.addDataSet to add them as the orange data set.
Use Layer.yZoneColor to create a y-zone color, which is blue for y >= 0 and orange for y < 0, and use Layer.setAggregateLabelStyle to apply it as the bar label color.
Use Axis.addZone to add two background zones for y >= 0 and y < 0.

[JSP Version] jspdemo/posnegbar.jsp

<%@page import="ChartDirector.*, java.util.*" %>
<%
// The data for the bar chart
double[] data = {-6.3, 2.3, 0.7, -3.4, 2.2, -2.9, -0.1, -0.1, 3.3, 6.2, 4.3, 1.6};

// The labels for the bar chart
String[] labels = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov",
    "Dec"};

// Create a XYChart object of size 500 x 320 pixels
XYChart c = new XYChart(500, 320);

// Add a title to the chart using Arial Bold Italic font
c.addTitle("Productivity Change - Year 2005", "Arial Bold Italic");

// Set the plotarea at (50, 30) and of size 400 x 250 pixels
c.setPlotArea(50, 30, 400, 250);

// Add a bar layer to the chart using the Overlay data combine method
BarLayer layer = c.addBarLayer2(Chart.Overlay);

// Select positive data and add it as data set with blue (6666ff) color
layer.addDataSet(new ArrayMath(data).selectGEZ(null, Chart.NoValue).result(), 0x6666ff);

// Select negative data and add it as data set with orange (ff6600) color
layer.addDataSet(new ArrayMath(data).selectLTZ(null, Chart.NoValue).result(), 0xff6600);

// Add labels to the top of the bar using 8 pt Arial Bold font. The font color is configured to be
// red (0xcc3300) below zero, and blue (0x3333ff) above zero.
layer.setAggregateLabelStyle("Arial Bold", 8, layer.yZoneColor(0, 0xcc3300, 0x3333ff));

// Set the labels on the x axis and use Arial Bold as the label font
c.xAxis().setLabels(labels).setFontStyle("Arial Bold");

// Draw the y axis on the right of the plot area
c.setYAxisOnRight(true);

// Use Arial Bold as the y axis label font
c.yAxis().setLabelStyle("Arial Bold");

// Add a title to the y axis
c.yAxis().setTitle("Percentage");

// Add a light blue (0xccccff) zone for positive part of the plot area
c.yAxis().addZone(0, 9999, 0xccccff);

// Add a pink (0xffffcc) zone for negative part of the plot area
c.yAxis().addZone(-9999, 0, 0xffcccc);

// Output the chart
WebChartViewer viewer = new WebChartViewer(request, "chart1");
viewer.setChart(c, Chart.SVG);

// Include tool tip for the chart
viewer.setImageMap(c.getHTMLImageMap("", "", "title='{xLabel}: {value}%'"));
%>
<!DOCTYPE html>
<html>
<head>
    <title>Positive Negative Bars</title>
    <!-- Include ChartDirector Javascript Library to support chart interactions -->
    <script type="text/javascript" src="cdjcv.js"></script>
</head>
<body style="margin:5px 0px 0px 5px">
    <div style="font:bold 18pt verdana;">
        Positive Negative Bars
    </div>
    <hr style="border:solid 1px #000080; background:#000080" />
    <div style="font:10pt 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>