FileDrop.java
/*
* Copyright (c) 2016 Vivid Solutions.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
* and the Eclipse Distribution License is available at
*
* http://www.eclipse.org/org/documents/edl-v10.php.
*/
package org.locationtech.jtstest.testbuilder.ui.dnd;
/**
* This class makes it easy to drag and drop files from the operating
* system to a Java program. Any <tt>java.awt.Component</tt> can be
* dropped onto, but only <tt>javax.swing.JComponent</tt>s will indicate
* the drop event with a changed border.
* <p/>
* To use this class, construct a new <tt>FileDrop</tt> by passing
* it the target component and a <tt>Listener</tt> to receive notification
* when file(s) have been dropped. Here is an example:
* <p/>
* <code><pre>
* JPanel myPanel = new JPanel();
* new FileDrop( myPanel, new FileDrop.Listener()
* { public void filesDropped( java.io.File[] files )
* {
* // handle file drop
* ...
* } // end filesDropped
* }); // end FileDrop.Listener
* </pre></code>
* <p/>
* You can specify the border that will appear when files are being dragged by
* calling the constructor with a <tt>javax.swing.border.Border</tt>. Only
* <tt>JComponent</tt>s will show any indication with a border.
* <p/>
* You can turn on some debugging features by passing a <tt>PrintStream</tt>
* object (such as <tt>System.out</tt>) into the full constructor. A <tt>null</tt>
* value will result in no extra debugging information being output.
* <p/>
*
* <p>I'm releasing this code into the Public Domain. Enjoy.
* </p>
* <p><em>Original author: Robert Harder, rharder@usa.net</em></p>
*
* @author Robert Harder
* @author rharder@usa.net
* @version 1.0
*/
public class FileDrop
{
private transient javax.swing.border.Border normalBorder;
private transient java.awt.dnd.DropTargetListener dropListener;
/** Discover if the running JVM is modern enough to have drag and drop. */
private static Boolean supportsDnD;
// Default border color
private static java.awt.Color defaultBorderColor = new java.awt.Color( 0f, 0f, 1f, 0.25f );
/**
* Constructs a {@link FileDrop} with a default light-blue border
* and, if <var>c</var> is a {@link java.awt.Container}, recursively
* sets all elements contained within as drop targets, though only
* the top level container will change borders.
*
* @param c Component on which files will be dropped.
* @param listener Listens for <tt>filesDropped</tt>.
* @since 1.0
*/
public FileDrop(
final java.awt.Component c,
final Listener listener )
{ this( null, // Logging stream
c, // Drop target
javax.swing.BorderFactory.createMatteBorder( 2, 2, 2, 2, defaultBorderColor ), // Drag border
true, // Recursive
listener );
} // end constructor
/**
* Constructor with a default border and the option to recursively set drop targets.
* If your component is a <tt>java.awt.Container</tt>, then each of its children
* components will also listen for drops, though only the parent will change borders.
*
* @param c Component on which files will be dropped.
* @param recursive Recursively set children as drop targets.
* @param listener Listens for <tt>filesDropped</tt>.
* @since 1.0
*/
public FileDrop(
final java.awt.Component c,
final boolean recursive,
final Listener listener )
{ this( null, // Logging stream
c, // Drop target
javax.swing.BorderFactory.createMatteBorder( 2, 2, 2, 2, defaultBorderColor ), // Drag border
recursive, // Recursive
listener );
} // end constructor
/**
* Constructor with a default border and debugging optionally turned on.
* With Debugging turned on, more status messages will be displayed to
* <tt>out</tt>. A common way to use this constructor is with
* <tt>System.out</tt> or <tt>System.err</tt>. A <tt>null</tt> value for
* the parameter <tt>out</tt> will result in no debugging output.
*
* @param out PrintStream to record debugging info or null for no debugging.
* @param c Component on which files will be dropped.
* @param listener Listens for <tt>filesDropped</tt>.
* @since 1.0
*/
public FileDrop(
final java.io.PrintStream out,
final java.awt.Component c,
final Listener listener )
{ this( out, // Logging stream
c, // Drop target
javax.swing.BorderFactory.createMatteBorder( 2, 2, 2, 2, defaultBorderColor ),
false, // Recursive
listener );
} // end constructor
/**
* Constructor with a default border, debugging optionally turned on
* and the option to recursively set drop targets.
* If your component is a <tt>java.awt.Container</tt>, then each of its children
* components will also listen for drops, though only the parent will change borders.
* With Debugging turned on, more status messages will be displayed to
* <tt>out</tt>. A common way to use this constructor is with
* <tt>System.out</tt> or <tt>System.err</tt>. A <tt>null</tt> value for
* the parameter <tt>out</tt> will result in no debugging output.
*
* @param out PrintStream to record debugging info or null for no debugging.
* @param c Component on which files will be dropped.
* @param recursive Recursively set children as drop targets.
* @param listener Listens for <tt>filesDropped</tt>.
* @since 1.0
*/
public FileDrop(
final java.io.PrintStream out,
final java.awt.Component c,
final boolean recursive,
final Listener listener)
{ this( out, // Logging stream
c, // Drop target
javax.swing.BorderFactory.createMatteBorder( 2, 2, 2, 2, defaultBorderColor ), // Drag border
recursive, // Recursive
listener );
} // end constructor
/**
* Constructor with a specified border
*
* @param c Component on which files will be dropped.
* @param dragBorder Border to use on <tt>JComponent</tt> when dragging occurs.
* @param listener Listens for <tt>filesDropped</tt>.
* @since 1.0
*/
public FileDrop(
final java.awt.Component c,
final javax.swing.border.Border dragBorder,
final Listener listener)
{ this(
null, // Logging stream
c, // Drop target
dragBorder, // Drag border
false, // Recursive
listener );
} // end constructor
/**
* Constructor with a specified border and the option to recursively set drop targets.
* If your component is a <tt>java.awt.Container</tt>, then each of its children
* components will also listen for drops, though only the parent will change borders.
*
* @param c Component on which files will be dropped.
* @param dragBorder Border to use on <tt>JComponent</tt> when dragging occurs.
* @param recursive Recursively set children as drop targets.
* @param listener Listens for <tt>filesDropped</tt>.
* @since 1.0
*/
public FileDrop(
final java.awt.Component c,
final javax.swing.border.Border dragBorder,
final boolean recursive,
final Listener listener)
{ this(
null,
c,
dragBorder,
recursive,
listener );
} // end constructor
/**
* Constructor with a specified border and debugging optionally turned on.
* With Debugging turned on, more status messages will be displayed to
* <tt>out</tt>. A common way to use this constructor is with
* <tt>System.out</tt> or <tt>System.err</tt>. A <tt>null</tt> value for
* the parameter <tt>out</tt> will result in no debugging output.
*
* @param out PrintStream to record debugging info or null for no debugging.
* @param c Component on which files will be dropped.
* @param dragBorder Border to use on <tt>JComponent</tt> when dragging occurs.
* @param listener Listens for <tt>filesDropped</tt>.
* @since 1.0
*/
public FileDrop(
final java.io.PrintStream out,
final java.awt.Component c,
final javax.swing.border.Border dragBorder,
final Listener listener)
{ this(
out, // Logging stream
c, // Drop target
dragBorder, // Drag border
false, // Recursive
listener );
} // end constructor
/**
* Full constructor with a specified border and debugging optionally turned on.
* With Debugging turned on, more status messages will be displayed to
* <tt>out</tt>. A common way to use this constructor is with
* <tt>System.out</tt> or <tt>System.err</tt>. A <tt>null</tt> value for
* the parameter <tt>out</tt> will result in no debugging output.
*
* @param out PrintStream to record debugging info or null for no debugging.
* @param c Component on which files will be dropped.
* @param dragBorder Border to use on <tt>JComponent</tt> when dragging occurs.
* @param recursive Recursively set children as drop targets.
* @param listener Listens for <tt>filesDropped</tt>.
* @since 1.0
*/
public FileDrop(
final java.io.PrintStream out,
final java.awt.Component c,
final javax.swing.border.Border dragBorder,
final boolean recursive,
final Listener listener)
{
if( supportsDnD() )
{ // Make a drop listener
dropListener = new java.awt.dnd.DropTargetListener()
{ public void dragEnter( java.awt.dnd.DropTargetDragEvent evt )
{ log( out, "FileDrop: dragEnter event." );
// Is this an acceptable drag event?
if( isDragOk( out, evt ) )
{
// If it's a Swing component, set its border
if( c instanceof javax.swing.JComponent )
{ javax.swing.JComponent jc = (javax.swing.JComponent) c;
normalBorder = jc.getBorder();
log( out, "FileDrop: normal border saved." );
jc.setBorder( dragBorder );
log( out, "FileDrop: drag border set." );
} // end if: JComponent
// Acknowledge that it's okay to enter
//evt.acceptDrag( java.awt.dnd.DnDConstants.ACTION_COPY_OR_MOVE );
evt.acceptDrag( java.awt.dnd.DnDConstants.ACTION_COPY );
log( out, "FileDrop: event accepted." );
} // end if: drag ok
else
{ // Reject the drag event
evt.rejectDrag();
log( out, "FileDrop: event rejected." );
} // end else: drag not ok
} // end dragEnter
public void dragOver( java.awt.dnd.DropTargetDragEvent evt )
{ // This is called continually as long as the mouse is
// over the drag target.
} // end dragOver
public void drop( java.awt.dnd.DropTargetDropEvent evt )
{ log( out, "FileDrop: drop event." );
try
{ // Get whatever was dropped
java.awt.datatransfer.Transferable tr = evt.getTransferable();
// Is it a file list?
if (tr.isDataFlavorSupported (java.awt.datatransfer.DataFlavor.javaFileListFlavor))
{
// Say we'll take it.
//evt.acceptDrop ( java.awt.dnd.DnDConstants.ACTION_COPY_OR_MOVE );
evt.acceptDrop ( java.awt.dnd.DnDConstants.ACTION_COPY );
log( out, "FileDrop: file list accepted." );
// Get a useful list
java.util.List fileList = (java.util.List)
tr.getTransferData(java.awt.datatransfer.DataFlavor.javaFileListFlavor);
java.util.Iterator iterator = fileList.iterator();
// Convert list to array
java.io.File[] filesTemp = new java.io.File[ fileList.size() ];
fileList.toArray( filesTemp );
final java.io.File[] files = filesTemp;
// Alert listener to drop.
if( listener != null )
listener.filesDropped( files );
// Mark that drop is completed.
evt.getDropTargetContext().dropComplete(true);
log( out, "FileDrop: drop complete." );
} // end if: file list
else
{ log( out, "FileDrop: not a file list - abort." );
evt.rejectDrop();
} // end else: not a file list
} // end try
catch ( java.io.IOException io)
{ log( out, "FileDrop: IOException - abort:" );
io.printStackTrace( out );
evt.rejectDrop();
} // end catch IOException
catch (java.awt.datatransfer.UnsupportedFlavorException ufe)
{ log( out, "FileDrop: UnsupportedFlavorException - abort:" );
ufe.printStackTrace( out );
evt.rejectDrop();
} // end catch: UnsupportedFlavorException
finally
{
// If it's a Swing component, reset its border
if( c instanceof javax.swing.JComponent )
{ javax.swing.JComponent jc = (javax.swing.JComponent) c;
jc.setBorder( normalBorder );
log( out, "FileDrop: normal border restored." );
} // end if: JComponent
} // end finally
} // end drop
public void dragExit( java.awt.dnd.DropTargetEvent evt )
{ log( out, "FileDrop: dragExit event." );
// If it's a Swing component, reset its border
if( c instanceof javax.swing.JComponent )
{ javax.swing.JComponent jc = (javax.swing.JComponent) c;
jc.setBorder( normalBorder );
log( out, "FileDrop: normal border restored." );
} // end if: JComponent
} // end dragExit
public void dropActionChanged( java.awt.dnd.DropTargetDragEvent evt )
{ log( out, "FileDrop: dropActionChanged event." );
// Is this an acceptable drag event?
if( isDragOk( out, evt ) )
{ //evt.acceptDrag( java.awt.dnd.DnDConstants.ACTION_COPY_OR_MOVE );
evt.acceptDrag( java.awt.dnd.DnDConstants.ACTION_COPY );
log( out, "FileDrop: event accepted." );
} // end if: drag ok
else
{ evt.rejectDrag();
log( out, "FileDrop: event rejected." );
} // end else: drag not ok
} // end dropActionChanged
}; // end DropTargetListener
// Make the component (and possibly children) drop targets
makeDropTarget( out, c, recursive );
} // end if: supports dnd
else
{ log( out, "FileDrop: Drag and drop is not supported with this JVM" );
} // end else: does not support DnD
} // end constructor
private static boolean supportsDnD()
{ // Static Boolean
if( supportsDnD == null )
{
boolean support = false;
try
{ Class arbitraryDndClass = Class.forName( "java.awt.dnd.DnDConstants" );
support = true;
} // end try
catch( Exception e )
{ support = false;
} // end catch
supportsDnD = Boolean.valueOf( support );
} // end if: first time through
return supportsDnD.booleanValue();
} // end supportsDnD
private void makeDropTarget( final java.io.PrintStream out, final java.awt.Component c, boolean recursive )
{
// Make drop target
final java.awt.dnd.DropTarget dt = new java.awt.dnd.DropTarget();
try
{ dt.addDropTargetListener( dropListener );
} // end try
catch( java.util.TooManyListenersException e )
{ e.printStackTrace();
log(out, "FileDrop: Drop will not work due to previous error. Do you have another listener attached?" );
} // end catch
// Listen for hierarchy changes and remove the drop target when the parent gets cleared out.
c.addHierarchyListener( new java.awt.event.HierarchyListener()
{ public void hierarchyChanged( java.awt.event.HierarchyEvent evt )
{ log( out, "FileDrop: Hierarchy changed." );
java.awt.Component parent = c.getParent();
if( parent == null )
{ c.setDropTarget( null );
log( out, "FileDrop: Drop target cleared from component." );
} // end if: null parent
else
{ new java.awt.dnd.DropTarget(c, dropListener);
log( out, "FileDrop: Drop target added to component." );
} // end else: parent not null
} // end hierarchyChanged
}); // end hierarchy listener
if( c.getParent() != null )
new java.awt.dnd.DropTarget(c, dropListener);
if( recursive && (c instanceof java.awt.Container ) )
{
// Get the container
java.awt.Container cont = (java.awt.Container) c;
// Get it's components
java.awt.Component[] comps = cont.getComponents();
// Set it's components as listeners also
for( int i = 0; i < comps.length; i++ )
makeDropTarget( out, comps[i], recursive );
} // end if: recursively set components as listener
} // end dropListener
/** Determine if the dragged data is a file list. */
private boolean isDragOk( final java.io.PrintStream out, final java.awt.dnd.DropTargetDragEvent evt )
{ boolean ok = false;
// Get data flavors being dragged
java.awt.datatransfer.DataFlavor[] flavors = evt.getCurrentDataFlavors();
// See if any of the flavors are a file list
int i = 0;
while( !ok && i < flavors.length )
{ // Is the flavor a file list?
if( flavors[i].equals( java.awt.datatransfer.DataFlavor.javaFileListFlavor ) )
ok = true;
i++;
} // end while: through flavors
// If logging is enabled, show data flavors
if( out != null )
{ if( flavors.length == 0 )
log( out, "FileDrop: no data flavors." );
for( i = 0; i < flavors.length; i++ )
log( out, flavors[i].toString() );
} // end if: logging enabled
return ok;
} // end isDragOk
/** Outputs <tt>message</tt> to <tt>out</tt> if it's not null. */
private static void log( java.io.PrintStream out, String message )
{ // Log message if requested
if( out != null )
out.println( message );
} // end log
/**
* Removes the drag-and-drop hooks from the component and optionally
* from the all children. You should call this if you add and remove
* components after you've set up the drag-and-drop.
* This will recursively unregister all components contained within
* <var>c</var> if <var>c</var> is a {@link java.awt.Container}.
*
* @param c The component to unregister as a drop target
* @since 1.0
*/
public static boolean remove( java.awt.Component c)
{ return remove( null, c, true );
} // end remove
/**
* Removes the drag-and-drop hooks from the component and optionally
* from the all children. You should call this if you add and remove
* components after you've set up the drag-and-drop.
*
* @param out Optional {@link java.io.PrintStream} for logging drag and drop messages
* @param c The component to unregister
* @param recursive Recursively unregister components within a container
* @since 1.0
*/
public static boolean remove( java.io.PrintStream out, java.awt.Component c, boolean recursive )
{ // Make sure we support dnd.
if( supportsDnD() )
{ log( out, "FileDrop: Removing drag-and-drop hooks." );
c.setDropTarget( null );
if( recursive && ( c instanceof java.awt.Container ) )
{ java.awt.Component[] comps = ((java.awt.Container)c).getComponents();
for( int i = 0; i < comps.length; i++ )
remove( out, comps[i], recursive );
return true;
} // end if: recursive
else return false;
} // end if: supports DnD
else return false;
} // end remove
/** Runs a sample program that shows dropped files */
public static void main( String[] args )
{
javax.swing.JFrame frame = new javax.swing.JFrame( "FileDrop" );
//javax.swing.border.TitledBorder dragBorder = new javax.swing.border.TitledBorder( "Drop 'em" );
final javax.swing.JTextArea text = new javax.swing.JTextArea();
frame.getContentPane().add(
new javax.swing.JScrollPane( text ),
java.awt.BorderLayout.CENTER );
new FileDrop( System.out, text, /*dragBorder,*/ new FileDrop.Listener()
{ public void filesDropped( java.io.File[] files )
{ for( int i = 0; i < files.length; i++ )
{ try
{ text.append( files[i].getCanonicalPath() + "\n" );
} // end try
catch( java.io.IOException e ) {}
} // end for: through each dropped file
} // end filesDropped
}); // end FileDrop.Listener
frame.setBounds( 100, 100, 300, 400 );
frame.setDefaultCloseOperation( frame.EXIT_ON_CLOSE );
frame.show();
} // end main
/* ******** I N N E R I N T E R F A C E L I S T E N E R ******** */
/**
* Implement this inner interface to listen for when files are dropped. For example
* your class declaration may begin like this:
* <code><pre>
* public class MyClass implements FileDrop.Listener
* ...
* public void filesDropped( java.io.File[] files )
* {
* ...
* } // end filesDropped
* ...
* </pre></code>
*
* @since 1.0
*/
public interface Listener
{
/**
* This method is called when files have been successfully dropped.
*
* @param files An array of <tt>File</tt>s that were dropped.
* @since 1.0
*/
public abstract void filesDropped( java.io.File[] files );
} // end inner-interface Listener
} // end class FileDrop