Variable Width Bar Chart

[JSP Version] jspdemo/varwidthbar.jsp
<%@page import="ChartDirector.*, java.util.*" %>
<%
// The data for the chart
double[] data = {800, 600, 1000, 1400};
double[] widths = {250, 500, 960, 460};
String[] labels = {"Wind", "Hydro", "Coal", "Natural Gas"};

// The colors to use
int[] colors = {0x00aa00, 0x66aaee, 0xee6622, 0xffbb00};

// Create a XYChart object of size 500 x 350 pixels
XYChart c = new XYChart(500, 350);

// Add a title to the chart using 15pt Arial Italic font
c.addTitle("Energy Generation Breakdown", "Arial Italic", 15);

// Set the plotarea at (60, 60) and of (chart_width - 90) x (chart_height - 100) in size. Use a
// vertical gradient color from light blue (f9f9ff) to sky blue (aaccff) as background. Set grid
// lines to white (ffffff).
int plotAreaBgColor = c.linearGradientColor(0, 60, 0, c.getHeight() - 40, 0xaaccff, 0xf9fcff);
c.setPlotArea(60, 60, c.getWidth() - 90, c.getHeight() - 100, plotAreaBgColor, -1, -1, 0xffffff);

// Add a legend box at (50, 30) using horizontal layout and transparent background.
c.addLegend(55, 30, false).setBackground(Chart.Transparent);

// Add titles to x/y axes with 10 points Arial Bold font
c.xAxis().setTitle("Mega Watts", "Arial Bold", 10);
c.yAxis().setTitle("Cost per MWh (dollars)", "Arial Bold", 10);

// Set the x axis rounding to false, so that the x-axis will fit the data exactly
c.xAxis().setRounding(false, false);

// In ChartDirector, there is no bar layer that can have variable bar widths, but you may create a
// bar using an area layer. (A bar can be considered as the area under a rectangular outline.) So by
// using a loop to create one bar per area layer, we can achieve a variable width bar chart.

// starting position of current bar
double currentX = 0;

for(int i = 0; i < data.length; ++i) {
    // ending position of current bar
    double nextX = currentX + widths[i];

    // outline of the bar
    double[] dataX = {currentX, currentX, nextX, nextX};
    double[] dataY = {0, data[i], data[i], 0};

    // create the area layer to fill the bar
    AreaLayer layer = c.addAreaLayer(dataY, colors[i], labels[i]);
    layer.setXData(dataX);

    // Tool tip for the layer
    layer.setHTMLImageMap("", "", "title='" + labels[i] + ": " + widths[i] + " MW at $" + data[i] +
        " per MWh'");

    // the ending position becomes the starting position of the next bar
    currentX = nextX;
}

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

// Include tool tip for the chart
viewer.setImageMap(c.getHTMLImageMap(""));
%>
<!DOCTYPE html>
<html>
<head>
    <title>Variable Width Bar Chart</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;">
        Variable Width Bar Chart
    </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>