ChartDirector 6.1 (Java Edition)

Tick Density


  

This example demonstrates how to control the axis tick density in auto-scaling.

By default, in auto-scaling, ChartDirector automatically chooses the tick spacing for the axis.

In some cases, you may want to suggest the tick spacing to use. This can be done by using Axis.setTickDensity.

Note that the actual tick spacing chosen by ChartDirector may not be equal to the suggested tick spacing. The suggested tick spacing is only a lower bound. It is because there may be other constraints when choosing the ticks. For example, the tick positions should be "neat numbers", such as (0, 5, 10, ...), and not arbitrary numbers like (0, 4.792, 9.584, ...). Also, by default, the axis starts and ends at tick positions (configurable using Axis.setRounding), which means the axis length must be divisible by the tick spacing. These and other constraints will affect the exact ticks being chosen.

In this example, one of the charts is drawn using the default tick spacing. The other chart is drawn using a suggested tick spacing of 10 pixels. Note that the actual tick spacing is slightly larger than 10 pixels.

Source Code Listing

[JSP Version] jspdemo/ticks.jsp
<%@page import="ChartDirector.*" %>
<%@page import="javax.servlet.http.*" %>
<%!
// A simple structure to represent a chart image with an image map
private static class ImageWithHotSpot
{
    String imageURL;
    String imageMap;
}

// Function to create the demo charts
ImageWithHotSpot createChart(HttpServletRequest request, int chartIndex)
{
    // The data for the chart
    double[] data = {100, 125, 265, 147, 67, 105};
    String[] labels = {"Jan", "Feb", "Mar", "Apr", "May", "Jun"};

    // Create a XYChart object of size 250 x 250 pixels
    XYChart c = new XYChart(250, 250);

    // Set the plot area at (27, 25) and of size 200 x 200 pixels
    c.setPlotArea(27, 25, 200, 200);

    if (chartIndex == 1) {
        // High tick density, uses 10 pixels as tick spacing
        c.addTitle("Tick Density = 10 pixels");
        c.yAxis().setTickDensity(10);
    } else {
        // Normal tick density, just use the default setting
        c.addTitle("Default Tick Density");
    }

    // Set the labels on the x axis
    c.xAxis().setLabels(labels);

    // Add a color bar layer using the given data. Use a 1 pixel 3D border for the bars.
    c.addBarLayer3(data).setBorderColor(-1, 1);

    // Output the chart
    ImageWithHotSpot ret = new ImageWithHotSpot();
    ret.imageURL = c.makeSession(request, "chart" + chartIndex);

    // Include tool tip for the chart
    ret.imageMap = c.getHTMLImageMap("", "", "title='Revenue for {xLabel}: US${value}M'");

    return ret;
}
%>
<%
ImageWithHotSpot chart0 = createChart(request, 0);
ImageWithHotSpot chart1 = createChart(request, 1);
%>
<html>
<body style="margin:5px 0px 0px 5px">
<div style="font-size:18pt; font-family:verdana; font-weight:bold">
    Tick Density
</div>
<hr color="#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>
<img src='<%=response.encodeURL("getchart.jsp?"+chart0.imageURL)%>'
    usemap="#map0" border="0">
<map name="map0"><%=chart0.imageMap%></map>
<img src='<%=response.encodeURL("getchart.jsp?"+chart1.imageURL)%>'
    usemap="#map1" border="0">
<map name="map1"><%=chart1.imageMap%></map>
</body>
</html>

[Java Version] javademo/ticks.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import ChartDirector.*;

public class ticks implements DemoModule
{
    //Name of demo program
    public String toString() { return "Tick Density"; }

    //Number of charts produced in this demo
    public int getNoOfCharts() { return 2; }

    //Main code for creating charts
    public void createChart(ChartViewer viewer, int chartIndex)
    {
        // The data for the chart
        double[] data = {100, 125, 265, 147, 67, 105};
        String[] labels = {"Jan", "Feb", "Mar", "Apr", "May", "Jun"};

        // Create a XYChart object of size 250 x 250 pixels
        XYChart c = new XYChart(250, 250);

        // Set the plot area at (27, 25) and of size 200 x 200 pixels
        c.setPlotArea(27, 25, 200, 200);

        if (chartIndex == 1) {
            // High tick density, uses 10 pixels as tick spacing
            c.addTitle("Tick Density = 10 pixels");
            c.yAxis().setTickDensity(10);
        } else {
            // Normal tick density, just use the default setting
            c.addTitle("Default Tick Density");
        }

        // Set the labels on the x axis
        c.xAxis().setLabels(labels);

        // Add a color bar layer using the given data. Use a 1 pixel 3D border for the bars.
        c.addBarLayer3(data).setBorderColor(-1, 1);

        // Output the chart
        viewer.setChart(c);

        //include tool tip for the chart
        viewer.setImageMap(c.getHTMLImageMap("clickable", "",
            "title='Revenue for {xLabel}: US${value}M'"));
    }

    //Allow this module to run as standalone program for easy testing
    public static void main(String[] args)
    {
        //Instantiate an instance of this demo module
        DemoModule demo = new ticks();

        //Create and set up the main window
        JFrame frame = new JFrame(demo.toString());
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {System.exit(0);} });
        frame.getContentPane().setBackground(Color.white);
        frame.getContentPane().setLayout(new FlowLayout(FlowLayout.LEFT));
        frame.setSize(800, 450);

        // Create the charts and put them in the content pane
        for (int i = 0; i < demo.getNoOfCharts(); ++i)
        {
            ChartViewer viewer = new ChartViewer();
            demo.createChart(viewer, i);
            frame.getContentPane().add(viewer);
        }

        // Display the window
        frame.setVisible(true);
    }
}