scribblecutandpaste.java

164个完整的Java程序源代码,包括了19种Java技术的164个类源代码

/*
 * 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.datatransfer;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.datatransfer.*;  // Clipboard, Transferable, DataFlavor, etc.

/** 
 * This component allows the user to scribble in a window, and to cut and
 * paste scribbles between windows.  It stores mouse coordinates in a Scribble
 * object, which is used to draw the scribble, and also to transfer the
 * scribble to and from the clipboard.  A JPopupMenu provides access to the
 * cut, copy, and paste commands.
 **/
public class ScribbleCutAndPaste extends JComponent
    implements ActionListener, ClipboardOwner 
{
    Stroke linestyle = new BasicStroke(3.0f); // Draw with wide lines
    Scribble scribble = new Scribble();       // Holds our scribble
    Scribble selection;                       // A copy of the scribble as cut
    JPopupMenu popup;                         // A menu for cut-and-paste

    public ScribbleCutAndPaste() {
	// Create the popup menu.
	String[] labels = new String[] {   "Clear", "Cut", "Copy", "Paste" };
	String[] commands = new String[] { "clear", "cut", "copy", "paste" };
	popup = new JPopupMenu();                    // Create the menu
	popup.setLabel("Edit");
	for(int i = 0; i < labels.length; i++) {
	    JMenuItem mi = new JMenuItem(labels[i]); // Create a menu item 
	    mi.setActionCommand(commands[i]);        // Set its action command
	    mi.addActionListener(this);              // And its action listener
	    popup.add(mi);                           // Add item to the menu
	}
	// Finally, register the popup menu with the component it appears over
	this.add(popup);

	// Add event listeners to do the drawing and handle the popup
	addMouseListener(new MouseAdapter() {
		public void mousePressed(MouseEvent e) {
		    if (e.isPopupTrigger())
			popup.show((Component)e.getSource(),
				   e.getX(), e.getY());
		    else
			scribble.moveto(e.getX(), e.getY()); // start new line
		}
	    });

	addMouseMotionListener(new MouseMotionAdapter() {
		public void mouseDragged(MouseEvent e) {
		    // If this isn't mouse button 1, ignore it
		    if ((e.getModifiers() & InputEvent.BUTTON1_MASK) == 0)
			return;
		    scribble.lineto(e.getX(), e.getY());    // Add a line 
		    repaint();
		}
	    });
    }

    /** 
     * Draw the component.
     * This method relies on Scribble which implements Shape.
     **/
    public void paintComponent(Graphics g) {
	super.paintComponent(g);
	Graphics2D g2 = (Graphics2D) g;
	g2.setStroke(linestyle);   // Specify wide lines
	g2.draw(scribble);         // Draw the scribble
    }
    
    /** This is the ActionListener method invoked by the popup menu items */
    public void actionPerformed(ActionEvent event) {
	String command = event.getActionCommand();
	if (command.equals("clear")) clear();
	else if (command.equals("cut")) cut();
	else if (command.equals("copy")) copy();
	else if (command.equals("paste")) paste();
    }

    /** Clear the scribble.  Invoked by popup menu */
    void clear() {
	scribble = new Scribble();   // Get a new, empty scribble
	repaint();                   // And redraw everything.
    }

    /** 
     * Make a copy of the current Scribble and put it on the clipboard
     * We can do this because Scribble implements Transferable
     * The user invokes this method through the popup menu
     **/
    public void copy() {
	// Get system clipboard
	Clipboard c = this.getToolkit().getSystemClipboard();
	
	// Make a copy of the Scribble object to put on the clipboard
	selection = (Scribble) scribble.clone();
	
	// Put the copy on the clipboard
	c.setContents(selection,  // What to put on the clipboard
		      this);      // Who to notify when it is no longer there
    }

    /** 
     * The cut action is just like the copy action, except that we erase the
     * current scribble after copying it to the clipboard
     **/
    public void cut() {
	copy();
	clear();
    }

    /** 
     * The user invokes this method through the popup menu.
     * First, ask for the Transferable contents of the system clipboard.
     * Then ask that Transferable object for the scribble data it represents.
     * Try using both data flavors supported by the Scribble class.
     * If it doesn't work, beep to tell the user it failed.
     **/
    public void paste() {
	Clipboard c = this.getToolkit().getSystemClipboard(); // Get clipboard
	Transferable t = c.getContents(this);            // Get its contents

	// Now try to get a Scribble object from the transferrable
	Scribble pastedScribble = null;
	try { 
	    pastedScribble =
		(Scribble)t.getTransferData(Scribble.scribbleDataFlavor);
	}
	catch (Exception e) { // UnsupportedFlavor, NullPointer, etc.
	    // If that didn't work, try asking for a string instead.
	    try {
		String s = (String)t.getTransferData(DataFlavor.stringFlavor);
		// We got a string, so try converting it to a Scribble
		pastedScribble = Scribble.parse(s);
	    }
	    catch (Exception e2) { // UnsupportedFlavor, NumberFormat, etc.
		// If we couldn't get and parse a string, give up
		this.getToolkit().beep();   // Tell the user the paste failed
		return;
	    }
	}

	// If we get here, we've retrieved a Scribble object from the clipboard
	// Add it to the current scribble, and ask to be redrawn
	scribble.append(pastedScribble);
	repaint();
    }
    
    /** 
     * This method implements the ClipboardOwner interface.  We specify a
     * ClipboardOwner when we copy a Scribble to the clipboard.  This method
     * will be invoked when something else is copied to the clipboard, and
     * bumps our data off the clipboard.  When this method is invoked we no
     * longer have to maintain our copied Scribble object, since it is no
     * longer available to be pasted.  Often, a component will highlight a
     * selected object while it is on the clipboard, and will use this method
     * to un-highlight the object when it is no longer on the clipboard.
     **/
    public void lostOwnership(Clipboard c, Transferable t) {
	selection = null;
    }
    
    /** A simple main method to test the class. */
    public static void main(String[] args) {
	JFrame frame = new JFrame("ScribbleCutAndPaste");
	ScribbleCutAndPaste s = new ScribbleCutAndPaste();
	frame.getContentPane().add(s, BorderLayout.CENTER);
	frame.setSize(400, 400);
	frame.setVisible(true);
    }
}