/* * Copyright (c) 2000 David Flanagan.  All rights reserved. * This code is from the book Java Examples in a Nutshell, 2nd Edition. * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied. * You may study, use, and modify it for any non-commercial purpose. * You may distribute it non-commercially as long as you retain this notice. * For a commercial use license, or to purchase the book (recommended), * visit http://www.davidflanagan.com/javaexamples2. */package com.davidflanagan.examples.gui;import java.awt.*;import java.awt.event.*;import java.util.Vector;public class AppletMenuBar extends Panel {    // Menubar contents    Vector labels = new Vector();    Vector menus = new Vector();    // Properties    Insets margins = new Insets(3, 10, 3, 10); // top, left, bottom, right    int spacing = 10;              // Space between menu labels    Color highlightColor;          // Rollover color for labels    // internal stuff    boolean remeasure = true;      // Whether the labels need to be remeasured    int[] widths;                          // The width of each label    int[] startPositions;                  // Where each label starts    int ascent, descent;                   // Font metrics    Dimension prefsize = new Dimension();  // How big do we want to be?    int highlightedItem = -1;              // Which item is the mouse over?    /**     * Create a new component that simulates a menubar by displaying     * the specified labels.  Whenever the user clicks the specified label,     * popup up the PopupMenu specified in the menus array.     * Elements of the menus arra may be a static PopupMenu object, or     * a PopupMenuFactory object for dynamically creating menus.     * Perhaps we'll also provide some other kind of constructor or factory     * method that reads popup menus out of a config file.     */    public AppletMenuBar() {	// We'd like these kinds of events to be delivered	enableEvents(AWTEvent.MOUSE_EVENT_MASK |		     AWTEvent.MOUSE_MOTION_EVENT_MASK);    }    /** Add a popup menu to the menubar */    public void addMenu(String label, PopupMenu menu) {	insertMenu(label, menu, -1);    }    /** Insert a popup menu into the menubar */    public void insertMenu(String label, PopupMenu menu, int index) {	if (index < 0) index += labels.size()+1;  // Position to put it at	this.add(menu);                           // Popup belongs to us	labels.insertElementAt(label, index);     // Remember the label	menus.insertElementAt(menu, index);       // Remember the menu	remeasure = true;                         // Remeasure everything	invalidate();                             // Container must relayout    }    /** Property accessor methods for margins property */    public Insets getMargins() { return (Insets) margins.clone(); }    public void setMargins(Insets margins) {	this.margins = margins;	remeasure = true;	invalidate();    }    /** Property accessor methods for spacing property */    public int getSpacing() { return spacing; }    public void setSpacing(int spacing) {	if (this.spacing != spacing) {	    this.spacing = spacing;	    remeasure = true;	    invalidate();	}    }    /** Accessor methods for highlightColor property */    public Color getHighlightColor() {	if (highlightColor == null) return getForeground();	else return highlightColor;    }    public void setHighlightColor(Color c) {	if (highlightColor != c) {	    highlightColor = c;	    repaint();	}    }    /** We override the setFont() method so we can remeasure */    public void setFont(Font f) {	super.setFont(f);	remeasure = true;	invalidate();    }    /** Override these color property setter method so we can repaint */    public void setForeground(Color c) {	super.setForeground(c);	repaint();    }    public void setBackground(Color c) {	super.setBackground(c);	repaint();    }    /**     * This method is called to draw tell the component to redraw itself.     * If we were implementing a Swing component, we'd override      * paintComponent() instead     **/    public void paint(Graphics g) {	if (remeasure) measure();  // Remeasure everything first, if needed		// Figure out Y coordinate to draw at	Dimension size = getSize();	int baseline = size.height - margins.bottom - descent;	// Set the font to draw with	g.setFont(getFont());	// Loop through the labels	int nummenus = labels.size();	for(int i = 0; i < nummenus; i++) {	    // Set the drawing color.  Highlight the current item	    if ((i == highlightedItem) && (highlightColor != null))		g.setColor(getHighlightColor());	    else		g.setColor(getForeground());	    // Draw the menu label at the position computed in measure()	    g.drawString((String)labels.elementAt(i), 			 startPositions[i], baseline);	}	// Now draw a groove at the bottom of the menubar.	Color bg = getBackground();	g.setColor(bg.darker());	g.drawLine(0, size.height-2, size.width, size.height-2);	g.setColor(bg.brighter());	g.drawLine(0, size.height-1, size.width, size.height-1);    }    /** Called when a mouse event happens over the menubar */    protected void processMouseEvent(MouseEvent e) {	int type = e.getID();             // What type of event?	int item = findItemAt(e.getX());  // Over which menu label?	if (type == MouseEvent.MOUSE_PRESSED) {	    // If it was a mouse down event, then pop up the menu	    if (item == -1) return;	    Dimension size = getSize();	    PopupMenu pm = (PopupMenu) menus.elementAt(item);	    if (pm != null) pm.show(this, startPositions[item]-3, size.height);	}	else if (type == MouseEvent.MOUSE_EXITED) {	    // If the mouse left the menubar, then unhighlight	    if (highlightedItem != -1) {		highlightedItem = -1;		if (highlightColor != null) repaint();	    }	}	else if ((type == MouseEvent.MOUSE_MOVED) || 		 (type == MouseEvent.MOUSE_ENTERED)) {	    // If the mouse moved, change the highlighted item, if necessary	    if (item != highlightedItem) {		highlightedItem = item;		if (highlightColor != null) repaint();	    }	}    }    /** This method is called when the mouse moves */    protected void processMouseMotionEvent(MouseEvent e) {	processMouseEvent(e);    }    /** This utility method converts an X coordinate to a menu label index */    protected int findItemAt(int x) {	// This could be a more efficient search...	int nummenus = labels.size();	int halfspace = spacing/2-1;	int i;	for(i = nummenus-1; i >= 0; i--) {	    if ((x >= startPositions[i]-halfspace) && 		(x <= startPositions[i]+widths[i]+halfspace)) break;	}	return i;    }    /**     * Measure the menu labels, and figure out their positions, so we     * can determine when a click happens, and so we can redraw efficiently.     **/    protected void measure() {	// Get information about the font	FontMetrics fm = this.getFontMetrics(getFont());	// Remember the basic font size	ascent = fm.getAscent();	descent = fm.getDescent();	// Create arrays to hold the measurements and positions	int nummenus = labels.size();	widths = new int[nummenus];	startPositions = new int[nummenus];	// Measure the label strings and	// figure out the starting position of each label	int pos = margins.left;	for(int i = 0; i < nummenus; i++) {	    startPositions[i] = pos;	    String label = (String)labels.elementAt(i);	    widths[i] = fm.stringWidth(label);	    pos += widths[i] + spacing;	}	// Compute our preferred size from this data	prefsize.width = pos - spacing + margins.right;	prefsize.height = ascent + descent + margins.top + margins.bottom;	// We've don't need to be remeasured anymore.	remeasure = false;    }    /**     * These methods tell the container how big the menubar wants to be.     *      **/    public Dimension getMinimumSize() { return getPreferredSize(); }    public Dimension getPreferredSize() {	if (remeasure) measure();	return prefsize;    }    /** @deprecated Here for compatibility with Java 1.0 */    public Dimension minimumSize() { return getPreferredSize(); }    /** @deprecated Here for compatibility with Java 1.0 */    public Dimension preferredSize() { return getPreferredSize(); }    /**      * This method is called when the underlying AWT component is created.     * We can't measure ourselves (no font metrics) until this is called.     **/    public void addNotify() {	super.addNotify();	measure();    }    /** This method tells the container not to give us keyboard focus */    public boolean isFocusTraversable() { return false; }}