Lesson Five - ColorScribble

The APPLET Tag

   <APPLET code="ColorScribble.class" width=300 height=300>
   <PARAM name="foreground" value="0000FF">
   <PARAM name="background" value="FFCCCC">
   </APPLET>

Program Listing

// This example is from the book _Java in a Nutshell_ by David Flanagan.
// Written by David Flanagan.  Copyright (c) 1996 O'Reilly & Associates.
// You may study, use, modify, and distribute this example for any purpose.
// This example is provided WITHOUT WARRANTY either expressed or implied.

import java.applet.*;
import java.awt.*;

public class ColorScribble extends Scribble {
    // Read in two color parameters and set the colors.
    public void init() {
        super.init();
        Color foreground = getColorParameter("foreground");
        Color background = getColorParameter("background");
        if (foreground != null) this.setForeground(foreground);
        if (background != null) this.setBackground(background);
    }
    
    // Read the specified parameter.  Interpret it as a hexidecimal
    // number of the form RRGGBB and convert it to a color.
    protected Color getColorParameter(String name) {
        String value = this.getParameter(name);
        int intvalue;
        try { intvalue = Integer.parseInt(value, 16); }
        catch (NumberFormatException e) { return null; }
        return new Color(intvalue);
    }
    
    // Return info about the supported parameters.  Web browsers and applet
    // viewers should display this information, and may also allow users to
    // set the parameter values.
    public String[][] getParameterInfo() {
        String[][] info = {
            // Array of arrays of strings describing each parameter.
            // Format: parameter name, parameter type, parameter description
            {"foreground", "hexidecimal color value", "foreground color"},
            {"background", "hexidecimal color value", "background color"}
        };
        return info;
    }
    
    // Return information suitable for display in an About dialog box.
    public String getAppletInfo() {
        return "Scribble v. 0.02.\nWritten by David Flanagan.";
    }
}