Discrete Heat Map

This example demonstrates the basic steps in creating a discrete heat map.

A discrete heat map consists of rectangular cells in a grid of which the cell color depends on its data value.

Create an XYChart object using XYChart.XYChart.
Specify the plot area of the chart using XYChart.setPlotArea. The plot area is the rectangle bounded by the x and y axes. You should leave some margin on the outside of the plot area for axis labels, chart titles, etc.
Add a discrete heat map layer using XYChart.addDiscreteHeatMapLayer.
Specify the labels on the x-axis and y-axis using Axis.setLabels. Shift the labels by 0.5 units using Axis.setOffset to align the labels with the cell center. (The default is to align the labels with the grid lines.)
The color axis (visually represented as the color legend) is positioned vertically to the right of the plot area using DiscreteHeatMapLayer.setColorAxis.
Assign the chart to the WebChartViewer using WebChartViewer.setChart, and insert it to the web page using WebChartViewer.renderHTML.
Generate tool tips for the chart using BaseChart.getHTMLImageMap.

[JSP Version] jspdemo/discreteheatmap.jsp

<%@page import="ChartDirector.*, java.util.*" %>
<%
// The x-axis and y-axis labels
String[] xLabels = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J"};
String[] yLabels = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9"};

// Random data for the 10 x 10 cells
RanSeries r = new RanSeries(2);
double[] zData = r.get2DSeries(xLabels.length, yLabels.length, 0, 100);

// Create an XYChart object of size 520 x 470 pixels.
XYChart c = new XYChart(520, 470);

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

// Create a discrete heat map with 10 x 10 cells
DiscreteHeatMapLayer layer = c.addDiscreteHeatMapLayer(zData, xLabels.length);

// Set the x-axis labels. Use 8pt Arial Bold font. Set axis stem to transparent, so only the labels
// are visible. Set 0.5 offset to position the labels in between the grid lines.
c.xAxis().setLabels(xLabels);
c.xAxis().setLabelStyle("Arial Bold", 8);
c.xAxis().setColors(Chart.Transparent, Chart.TextColor);
c.xAxis().setLabelOffset(0.5);
c.xAxis().setTitle("X Axis Title Placeholder", "Arial Bold", 12);

// Set the y-axis labels. Use 8pt Arial Bold font. Set axis stem to transparent, so only the labels
// are visible. Set 0.5 offset to position the labels in between the grid lines.
c.yAxis().setLabels(yLabels);
c.yAxis().setLabelStyle("Arial Bold", 8);
c.yAxis().setColors(Chart.Transparent, Chart.TextColor);
c.yAxis().setLabelOffset(0.5);
c.yAxis().setTitle("Y Axis Title Placeholder", "Arial Bold", 12);

// Position the color axis 20 pixels to the right of the plot area and of the same height as the
// plot area. Put the labels on the right side of the color axis. Use 8pt Arial Bold font for the
// labels.
ColorAxis cAxis = layer.setColorAxis(p.getRightX() + 20, p.getTopY(), Chart.TopLeft, p.getHeight(),
    Chart.Right);
cAxis.setLabelStyle("Arial Bold", 8);

// 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='<*cdml*>({xLabel}, {yLabel}) = {z|2}'"));
%>
<!DOCTYPE html>
<html>
<head>
    <title>Discrete Heat Map</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;">
        Discrete Heat Map
    </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>