I have an application of thumbnail viewer that requires displaying thumbnails with the feature to reorder them (using DnD).
The thumbnail is a custom component (JLayeredPane).
Here is the wire frame of the application to get a better idea.
Any directions/pointer to achieve or any existing component that can do reordering feature would be a great help.
Can I use JList with each element as a Thumbnail?
Note: I am not expecting the code here.
I basically stole this from the web and modified it slightly...
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.io.IOException;
import java.util.ArrayList;
import javax.swing.BorderFactory;
import javax.swing.DefaultListModel;
import javax.swing.DropMode;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.ListSelectionModel;
import javax.swing.TransferHandler;
public class TestListReorder extends JPanel {
ArrayListTransferHandler arrayListHandler;
public TestListReorder() {
arrayListHandler = new ArrayListTransferHandler();
JList list1, list2;
DefaultListModel list1Model = new DefaultListModel();
list1Model.addElement("0 (list 1)");
list1Model.addElement("1 (list 1)");
list1Model.addElement("2 (list 1)");
list1Model.addElement("3 (list 1)");
list1Model.addElement("4 (list 1)");
list1Model.addElement("5 (list 1)");
list1Model.addElement("6 (list 1)");
list1 = new JList(list1Model);
list1.setDropMode(DropMode.USE_SELECTION);
list1.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
list1.setTransferHandler(arrayListHandler);
list1.setDragEnabled(true);
JScrollPane list1View = new JScrollPane(list1);
list1View.setPreferredSize(new Dimension(200, 100));
JPanel panel1 = new JPanel();
panel1.setLayout(new BorderLayout());
panel1.add(list1View, BorderLayout.CENTER);
panel1.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
setLayout(new BorderLayout());
add(panel1, BorderLayout.LINE_START);
setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
}
/**
* Create the GUI and show it. For thread safety, this method should be
* invoked from the event-dispatching thread.
*/
private static void createAndShowGUI() {
//Make sure we have nice window decorations.
JFrame.setDefaultLookAndFeelDecorated(true);
//Create and set up the window.
JFrame frame = new JFrame("DragListDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Create and set up the content pane.
TestListReorder demo = new TestListReorder();
frame.setContentPane(demo);
//Display the window.
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
/*
* ArrayListTransferHandler.java is used by the 1.4 DragListDemo.java example.
*/
class ArrayListTransferHandler extends TransferHandler {
DataFlavor localArrayListFlavor, serialArrayListFlavor;
String localArrayListType = DataFlavor.javaJVMLocalObjectMimeType
+ ";class=java.util.ArrayList";
JList source = null;
int[] indices = null;
int addIndex = -1; //Location where items were added
int addCount = 0; //Number of items added
public ArrayListTransferHandler() {
try {
localArrayListFlavor = new DataFlavor(localArrayListType);
} catch (ClassNotFoundException e) {
System.out
.println("ArrayListTransferHandler: unable to create data flavor");
}
serialArrayListFlavor = new DataFlavor(ArrayList.class, "ArrayList");
}
public boolean importData(JComponent c, Transferable t) {
JList target = null;
ArrayList alist = null;
if (!canImport(c, t.getTransferDataFlavors())) {
return false;
}
try {
target = (JList) c;
if (hasLocalArrayListFlavor(t.getTransferDataFlavors())) {
alist = (ArrayList) t.getTransferData(localArrayListFlavor);
} else if (hasSerialArrayListFlavor(t.getTransferDataFlavors())) {
alist = (ArrayList) t.getTransferData(serialArrayListFlavor);
} else {
return false;
}
} catch (UnsupportedFlavorException ufe) {
System.out.println("importData: unsupported data flavor");
return false;
} catch (IOException ioe) {
System.out.println("importData: I/O exception");
return false;
}
//At this point we use the same code to retrieve the data
//locally or serially.
//We'll drop at the current selected index.
int index = target.getSelectedIndex();
//Prevent the user from dropping data back on itself.
//For example, if the user is moving items #4,#5,#6 and #7 and
//attempts to insert the items after item #5, this would
//be problematic when removing the original items.
//This is interpreted as dropping the same data on itself
//and has no effect.
if (source.equals(target)) {
if (indices != null && index >= indices[0] - 1
&& index <= indices[indices.length - 1]) {
indices = null;
return true;
}
}
DefaultListModel listModel = (DefaultListModel) target.getModel();
int max = listModel.getSize();
if (index < 0) {
index = max;
} else {
index++;
if (index > max) {
index = max;
}
}
addIndex = index;
addCount = alist.size();
for (int i = 0; i < alist.size(); i++) {
listModel.add(index++, alist.get(i));
}
return true;
}
protected void exportDone(JComponent c, Transferable data, int action) {
if ((action == MOVE) && (indices != null)) {
DefaultListModel model = (DefaultListModel) source.getModel();
//If we are moving items around in the same list, we
//need to adjust the indices accordingly since those
//after the insertion point have moved.
if (addCount > 0) {
for (int i = 0; i < indices.length; i++) {
if (indices[i] > addIndex) {
indices[i] += addCount;
}
}
}
for (int i = indices.length - 1; i >= 0; i--) {
model.remove(indices[i]);
}
}
indices = null;
addIndex = -1;
addCount = 0;
}
private boolean hasLocalArrayListFlavor(DataFlavor[] flavors) {
if (localArrayListFlavor == null) {
return false;
}
for (int i = 0; i < flavors.length; i++) {
if (flavors[i].equals(localArrayListFlavor)) {
return true;
}
}
return false;
}
private boolean hasSerialArrayListFlavor(DataFlavor[] flavors) {
if (serialArrayListFlavor == null) {
return false;
}
for (int i = 0; i < flavors.length; i++) {
if (flavors[i].equals(serialArrayListFlavor)) {
return true;
}
}
return false;
}
public boolean canImport(JComponent c, DataFlavor[] flavors) {
if (hasLocalArrayListFlavor(flavors)) {
return true;
}
if (hasSerialArrayListFlavor(flavors)) {
return true;
}
return false;
}
protected Transferable createTransferable(JComponent c) {
if (c instanceof JList) {
source = (JList) c;
indices = source.getSelectedIndices();
Object[] values = source.getSelectedValues();
if (values == null || values.length == 0) {
return null;
}
ArrayList alist = new ArrayList(values.length);
for (int i = 0; i < values.length; i++) {
Object o = values[i];
String str = o.toString();
if (str == null) {
str = "";
}
alist.add(str);
}
return new ArrayListTransferable(alist);
}
return null;
}
public int getSourceActions(JComponent c) {
return COPY_OR_MOVE;
}
public class ArrayListTransferable implements Transferable {
ArrayList data;
public ArrayListTransferable(ArrayList alist) {
data = alist;
}
public Object getTransferData(DataFlavor flavor)
throws UnsupportedFlavorException {
if (!isDataFlavorSupported(flavor)) {
throw new UnsupportedFlavorException(flavor);
}
return data;
}
public DataFlavor[] getTransferDataFlavors() {
return new DataFlavor[]{localArrayListFlavor,
serialArrayListFlavor};
}
public boolean isDataFlavorSupported(DataFlavor flavor) {
if (localArrayListFlavor.equals(flavor)) {
return true;
}
if (serialArrayListFlavor.equals(flavor)) {
return true;
}
return false;
}
}
}
You can see the original post here.
Personally, I don't like the new "component" drag'n'drop API, but in your case, it may be the simplest and fastest to implement...
This works pretty good but the original code contains a bug so that you cannot move several items at once without getting an error message you can avoid that simply by switching some code the exportDone function so that it looks like this
protected void exportDone(JComponent c, Transferable data, int action) {
if ((action == MOVE) && (indices != null)) {
DefaultListModel model = (DefaultListModel) source.getModel();
// If we are moving items around in the same list, we
// need to adjust the indices accordingly since those
// after the insertion point have moved.
for (int i = indices.length - 1; i >= 0; i--)
model.remove(indices[i]);
}
if (addCount > 0) {
for (int i = 0; i < indices.length; i++) {
if (indices[i] > addIndex) {
indices[i] += addCount;
}
}
}
indices = null;
addIndex = -1;
addCount = 0;
}
