/******************************************************************************* * * * File: Applet_03.java Revision: 1.0 * * * * Contents: an applet examining it's context * * * * Creation: 09.07.1996 Last Modification: 17.04.2002 * * * * Platform: IBM-compatible PC running Windows 98SE * * * * Environment: Java 1.4 * * * * Author: Andreas Rozek Phone: ++49 (711) 6770682 * * Kirschblütenweg 15 Fax: - * * D-70569 Stuttgart EMail: Andreas.Rozek@T-Online.De * * Germany * * * * URL: http://www.Andreas-Rozek.de/ * * * * Copyright: this software is published under the "GNU General Public Li- * * cense" (see "http://www.gnu.org/copyleft/gpl.html" for addi- * * tional information) * * * * Comments: meanwhile, the original source code (for Java 1.0.2) has been * * updated in order to compile under Java 1.1.8 and Java 1.4 w/o * * major problems * * * *******************************************************************************/ import java.applet.*; // basic applet classes import java.awt.*; // basic AWT classes (& interfaces) import java.io.*; // Java file handling and stream IO import java.util.*; // Java utility classes and data structures public class Applet_03 extends java.applet.Applet { /**** information about author, version and copyright of this applet ****/ final static String AppletInfo = // "Applet_03 - an example for applet parameter parsing\n" + "\n" + "Andreas Rozek\n" + "Kirschblütenweg 15\n" + "D-70569 Stuttgart\n" + "Germany\n" + "\n" + "Phone: ++49 (711) 6770682\n" + "Fax: -\n" + "EMail: Andreas.Rozek@T-Online.De\n" + "URL: http://www.Andreas-Rozek.de"; /**** information about foreseen applet parameters ****/ final static String[][] ParameterInfo = { {"Name", "String", "distinguishes the three different instances of Applet_03"} }; /**** desired applet insets ****/ final static Insets AppletInsets = new Insets(0,4,4,4); /**** for an easier instance discrimination ****/ int Variant; // indicates which if the 3 instances THIS applet is final static int AppletDisplay = 0; final static int AppletInfoDisplay = 1; final static int ParameterInfoDisplay = 2; /**** user interface components ****/ java.awt.List AppletList = null; // applet display TextArea AppletArea = null; // applet information display TextArea ParameterArea = null; // parameter information display /******************************************************************************* * * * getApplet provides an alternative to Netscape's buggy AppletContext method * * * *******************************************************************************/ public Applet getApplet (String AppletName) { Enumeration AppletSet = getAppletContext().getApplets(); while (AppletSet.hasMoreElements()) { Applet Neighbour = (Applet) AppletSet.nextElement(); String Name = Neighbour.getParameter("Name"); if ((Name != null) && Name.equals(AppletName)) return Neighbour; }; return null; }; /******************************************************************************* * * * getAppletInfo provides information about author, version and copyright * * * *******************************************************************************/ public String getAppletInfo () { String Name = getParameter("Name"); if (Name == null) { return "Applet_03\n" + AppletInfo; } else { return "Applet_03 - " + Name + "\n" + AppletInfo; } }; /******************************************************************************* * * * getInsets returns actual applet insets * * * *******************************************************************************/ public final Insets getInsets () { return AppletInsets; }; /******************************************************************************* * * * getParameter synchronized version of the original method * * * *******************************************************************************/ public synchronized String getParameter (String Name) { return super.getParameter(Name); }; /******************************************************************************* * * * getParameterInfo provides information about foreseen applet parameters * * * *******************************************************************************/ public String[][] getParameterInfo () { return ParameterInfo; // see above for definition of "ParameterInfo" }; /******************************************************************************* * * * handleEvent main event handler * * * *******************************************************************************/ public synchronized boolean handleEvent (Event AWTEvent) { if (AWTEvent.id == Event.LIST_SELECT) { AppletContext Context = getAppletContext(); /**** which applet has been selected? ****/ String AppletName = AppletList.getItem(((Integer) AWTEvent.arg).intValue()); // Applet AppletInstance = Context.getApplet(AppletName); Applet AppletInstance = getApplet(AppletName); if (AppletInstance == null) return false; // just to be sure... /**** show corresponding applet and parameter info ****/ // Applet_03 InfoDisplay = (Applet_03) Context.getApplet("Applet Information Display"); Applet_03 InfoDisplay = (Applet_03) getApplet("Applet Information Display"); if (InfoDisplay != null) { InfoDisplay.AppletArea.setText(AppletInstance.getAppletInfo()); }; // Applet_03 ParameterDisplay = (Applet_03) Context.getApplet("Parameter Information Display"); Applet_03 ParameterDisplay = (Applet_03) getApplet("Parameter Information Display"); if (ParameterDisplay != null) { String[][] ParameterInfo = AppletInstance.getParameterInfo(); ParameterDisplay.ParameterArea.setText(""); for (int i = 0; i < ParameterInfo.length; i++) { ParameterDisplay.ParameterArea.append( ParameterInfo[i][0] + " -- " + ParameterInfo[i][1] + " -- " + ParameterInfo[i][2] ); }; }; }; return false; }; /******************************************************************************* * * * init initialize an applet each time it's loaded or reloaded * * * *******************************************************************************/ public void init () { Label TextLabel; // temporarily stores a text label /**** determine, which of the three instances THIS applet is ****/ String Name = getParameter("Name"); if (Name == null) Name = "applet context examination"; int Variant = AppletDisplay; if (Name.equals("Applet Information Display")) Variant = AppletInfoDisplay; if (Name.equals("Parameter Information Display")) Variant = ParameterInfoDisplay; /**** unify the visual appearance of an applet on different platforms ****/ setBackground(Color.lightGray); setFont(new Font("Helvetica", Font.PLAIN, 11)); /**** prepare user interface ****/ setLayout(new GridBagLayout()); TextLabel = new Label("Applet_03 - " + Name); TextLabel.setFont(new Font("Helvetica", Font.BOLD, 12)); add_GridItem(TextLabel, 0,0, 1,1, fill_x, 0,0, 1,2,0,0, align_w, 0,0); add_GridItem(new ColorBox(0,2, Color.black), 0,1, 1,1, fill_x, 0,0, 0,0,4,0, align_w, 0,0); /**** distinguish between three different variants ****/ switch (Variant) { case AppletDisplay: TextLabel = new Label("List of available Applets:"); add_GridItem(TextLabel, 0,2, 1,1, fill_x, 0,0, 0,2,0,0, align_w, 0,0); AppletList = new java.awt.List(); add_GridItem(AppletList, 0,3, 1,1, fill_both, 0,0, 0,0,0,0, align_w, 9,9); /**** create a list of available applets ****/ Enumeration AppletSet = getAppletContext().getApplets(); while (AppletSet.hasMoreElements()) { Applet Neighbour = (Applet) AppletSet.nextElement(); AppletList.add(Neighbour.getParameter("Name")); }; break; case AppletInfoDisplay: TextLabel = new Label("Applet Information:"); add_GridItem(TextLabel, 0,2, 1,1, fill_x, 0,0, 0,2,0,0, align_w, 0,0); AppletArea = new TextArea(); AppletArea.setText("(no applet selected)"); add_GridItem(AppletArea, 0,3, 1,1, fill_both, 0,0, 0,0,0,0, align_w, 9,9); break; case ParameterInfoDisplay: TextLabel = new Label("Parameter Information:"); add_GridItem(TextLabel, 0,2, 1,1, fill_x, 0,0, 0,2,0,0, align_w, 0,0); ParameterArea = new TextArea(); ParameterArea.setText("(no applet selected)"); add_GridItem(ParameterArea, 0,3, 1,1, fill_both, 0,0, 0,0,0,0, align_w, 9,9); }; /**** resize and show applet ****/ // resize(preferredSize()); setVisible(true); }; /******************************************************************************* * * * paint (re)draws applet contents * * * *******************************************************************************/ public void paint (Graphics Graf) { int Width = getSize().width-1; // "cache" applet dimensions int Height = getSize().height-1; /**** draw border with "3D" effect ****/ Graf.setColor(Color.white); Graf.drawLine(0,0, Width-1,0); Graf.drawLine(0,0, 0,Height); Graf.setColor(Color.gray); Graf.drawLine(Width,0, Width,Height); Graf.drawLine(1,Height, Width,Height); }; /******************************************************************************* * * * Assisting Fields and Methods * * * *******************************************************************************/ /**** local equivalents of "GridBagConstraints" constants ****/ final static int align_c = GridBagConstraints.CENTER; final static int align_n = GridBagConstraints.NORTH; final static int align_ne = GridBagConstraints.NORTHEAST; final static int align_e = GridBagConstraints.EAST; final static int align_se = GridBagConstraints.SOUTHEAST; final static int align_s = GridBagConstraints.SOUTH; final static int align_sw = GridBagConstraints.SOUTHWEST; final static int align_w = GridBagConstraints.WEST; final static int align_nw = GridBagConstraints.NORTHWEST; final static int fill_none = GridBagConstraints.NONE; final static int fill_x = GridBagConstraints.HORIZONTAL; final static int fill_y = GridBagConstraints.VERTICAL; final static int fill_both = GridBagConstraints.BOTH; /******************************************************************************* * * * add_GridItem adds a "Component" to a "GridBag" using the given constraints * * * *******************************************************************************/ void add_GridItem ( Component Item, // the item to be added to the grid int GridX, // leftmost column to be occupied by a grid element int GridY, // topmost row to be occupied by a grid element int GridWidth, // number of columns to be occupied by a grid element int GridHeight, // number of rows to be occupied by a grid element int Fill, // in which direction should a grid element be expanded? int IPadX, // internal horizontal padding int IPadY, // internal vertical padding int InsetTop, // top margin between cell and grid element int InsetLeft, // left margin between cell and grid element int InsetBottom, // bottom margin between cell and grid element int InsetRight, // right margin between cell and grid element int Anchor, // grid element alignment inside a cell int WeightX, // element "priority" for gaining extra horizontal space int WeightY // element "priority" for gaining extra vertical space ) { if (Item == null) return; /**** create a new "GridBagConstraints" object... ****/ GridBagConstraints Constraints = new GridBagConstraints(); /**** fill in the given arguments... ****/ Constraints.gridx = GridX; Constraints.gridy = GridY; Constraints.gridwidth = GridWidth; Constraints.gridheight = GridHeight; Constraints.fill = Fill; Constraints.ipadx = IPadX; Constraints.ipady = IPadY; Constraints.insets = new Insets(InsetTop, InsetLeft, InsetBottom, InsetRight); Constraints.anchor = Anchor; Constraints.weightx = Math.max(0,Math.min(99,WeightX)) * 100.0; Constraints.weighty = Math.max(0,Math.min(99,WeightY)) * 100.0; /**** then add "Item" using the given constraints ****/ add(Item); ((GridBagLayout) getLayout()).setConstraints(Item,Constraints); }; }; /******************************************************************************* * * * ColorBox * * * *******************************************************************************/ class ColorBox extends Canvas { int Width, Height; // desired dimensions public ColorBox (int LineWidth, int LineHeight, Color LineColor) { super(); // just to be complete Width = Math.max(0,LineWidth); Height = Math.max(0,LineHeight); setBackground(LineColor); }; public Dimension getMinimumSize () { return new Dimension((Width == 0 ? 1 : Width),(Height == 0 ? 1 : Height)); }; public Dimension getPreferredSize () { return new Dimension((Width == 0 ? Math.max(getSize().width, 1) : Width), (Height == 0 ? Math.max(getSize().height,1) : Height)); }; };