This program demonstrates drag and drop in an image list.
/*
This program is a part of the companion code for Core Java 8th ed.
(http://horstmann.com/corejava)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.DefaultListModel;
import javax.swing.DropMode;
import javax.swing.ImageIcon;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.TransferHandler;
/**
* This program demonstrates drag and drop in an image list.
*
* @version 1.00 2007-09-20
* @author Cay Horstmann
*/
public class ImageListDnDTest {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
JFrame frame = new ImageListDnDFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
});
}
}
class ImageListDnDFrame extends JFrame {
public ImageListDnDFrame() {
setTitle("ImageListDnDTest");
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
list1 = new ImageList(new File("images1").listFiles());
list2 = new ImageList(new File("images2").listFiles());
setLayout(new GridLayout(2, 1));
add(new JScrollPane(list1));
add(new JScrollPane(list2));
}
private ImageList list1;
private ImageList list2;
private static final int DEFAULT_WIDTH = 600;
private static final int DEFAULT_HEIGHT = 500;
}
class ImageList extends JList {
public ImageList(File[] imageFiles) {
DefaultListModel model = new DefaultListModel();
for (File f : imageFiles)
model.addElement(new ImageIcon(f.getPath()));
setModel(model);
setVisibleRowCount(0);
setLayoutOrientation(JList.HORIZONTAL_WRAP);
setDragEnabled(true);
setDropMode(DropMode.ON_OR_INSERT);
setTransferHandler(new ImageListTransferHandler());
}
}
class ImageListTransferHandler extends TransferHandler {
// Support for drag
public int getSourceActions(JComponent source) {
return COPY_OR_MOVE;
}
protected Transferable createTransferable(JComponent source) {
JList list = (JList) source;
int index = list.getSelectedIndex();
if (index < 0)
return null;
ImageIcon icon = (ImageIcon) list.getModel().getElementAt(index);
return new ImageTransferable(icon.getImage());
}
protected void exportDone(JComponent source, Transferable data, int action) {
if (action == MOVE) {
JList list = (JList) source;
int index = list.getSelectedIndex();
if (index < 0)
return;
DefaultListModel model = (DefaultListModel) list.getModel();
model.remove(index);
}
}
// Support for drop
public boolean canImport(TransferSupport support) {
if (support.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
if (support.getUserDropAction() == MOVE)
support.setDropAction(COPY);
return true;
} else
return support.isDataFlavorSupported(DataFlavor.imageFlavor);
}
public boolean importData(TransferSupport support) {
JList list = (JList) support.getComponent();
DefaultListModel model = (DefaultListModel) list.getModel();
Transferable transferable = support.getTransferable();
List<DataFlavor> flavors = Arrays.asList(transferable.getTransferDataFlavors());
List<Image> images = new ArrayList<Image>();
try {
if (flavors.contains(DataFlavor.javaFileListFlavor)) {
List<File> fileList = (List<File>) transferable
.getTransferData(DataFlavor.javaFileListFlavor);
for (File f : fileList) {
try {
images.add(ImageIO.read(f));
} catch (IOException ex) {
// couldn't read image--skip
}
}
} else if (flavors.contains(DataFlavor.imageFlavor)) {
images.add((Image) transferable.getTransferData(DataFlavor.imageFlavor));
}
int index;
if (support.isDrop()) {
JList.DropLocation location = (JList.DropLocation) support.getDropLocation();
index = location.getIndex();
if (!location.isInsert())
model.remove(index); // replace location
} else
index = model.size();
for (Image image : images) {
model.add(index, new ImageIcon(image));
index++;
}
return true;
} catch (IOException ex) {
return false;
} catch (UnsupportedFlavorException ex) {
return false;
}
}
}
/*
* This program is a part of the companion code for Core Java 8th ed.
* (http://horstmann.com/corejava)
*
* This program is free software: you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* This class is a wrapper for the data transfer of image objects.
*/
class ImageTransferable implements Transferable {
/**
* Constructs the selection.
*
* @param image
* an image
*/
public ImageTransferable(Image image) {
theImage = image;
}
public DataFlavor[] getTransferDataFlavors() {
return new DataFlavor[] { DataFlavor.imageFlavor };
}
public boolean isDataFlavorSupported(DataFlavor flavor) {
return flavor.equals(DataFlavor.imageFlavor);
}
public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException {
if (flavor.equals(DataFlavor.imageFlavor)) {
return theImage;
} else {
throw new UnsupportedFlavorException(flavor);
}
}
private Image theImage;
}
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