Here's hoping someone else gets a head start.
LeftTabs.java is a simple expandable application based on the SWT Java framework that has a "list" of "items" on the left, and on the right a "view" that will display their data.
The list is implemented by a tree. You can assign your own custom data type to each treeItem. You can create new items with a right-click pop-up menu. You can delete or drag and drop any item in the tree. Your custom data associated with the treeItem will be meticulously preserved. You can update the data in the view on the right and the changes will be synced back to your custom data type in the selected treeItem - automatically.
It's not all that surprising that more templates like this aren't available. It was rather difficult to but together. But there was lots of resources that went into making this possible. Many elements in this code are based on examples taken from: www.java2s.com
/*
* Basic template for app with left hand tabs
* and custom pane on right
* by clay.dot.gerrard.at.gmail.dot.com
*/
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.swt.widgets.MenuItem;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeItem;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.MessageBox;
import org.eclipse.swt.dnd.*;
import org.eclipse.swt.layout.*;
public class LeftTabs {
// left hand "tab" tree
static Tree tree;
// right hand viewer
static CompositePane view;
// temporary TreeItem used to hold data during Drag & Drop
static TreeItem sourceTreeItem;
// keep track of number of treeItems created
static int count = 1;
public static void main(String[] args) {
// setup the display & shell & layout
final Display display = new Display();
final Shell shell = new Shell(display);
FillLayout fillLayout = new FillLayout();
// columns
fillLayout.type = SWT.HORIZONTAL;
// break 'em up a little
fillLayout.spacing = 3;
fillLayout.marginHeight = 3;
shell.setLayout(fillLayout);
// And here's the tree
tree = new Tree(shell, SWT.BORDER);
// filled with some data
for (int i = 1; i <= 3; i++) {
TreeItemData myData = new TreeItemData();
myData.Name = "Item" + i;
myData.field1 = myData.Name + " Data";
TreeItem item = new TreeItem(tree, SWT.NONE);
count++;
item.setText(myData.Name);
item.setData(myData);
}
// And here's the right hand pane
view = new CompositePane(shell);
// right click menu on the tree
tree.addListener(SWT.MenuDetect, new Listener() {
public void handleEvent(Event event) {
Menu menu = new Menu(shell, SWT.POP_UP);
// NEW ITEM
MenuItem item_new = new MenuItem(menu, SWT.PUSH);
item_new.setText("New Item");
// when click "New Item", add an item to tree
item_new.addListener(SWT.Selection, new Listener() {
public void handleEvent(Event e) {
TreeItem[] selection = tree.getSelection();
int index;
if (selection.length != 0)
index = tree.indexOf(selection[0]) + 1;
else
index = 0;
TreeItem item = new TreeItem(tree, SWT.NONE, index);
TreeItemData myData = new TreeItemData();
myData.Name = "Item" + count++;
myData.field1 = myData.Name + " Data";
item.setText(myData.Name);
item.setData(myData);
view.setData((TreeItemData) item.getData());
tree.setSelection(item);
}
}); // end item_new event
// DELETE ITEM
MenuItem item_delete = new MenuItem(menu, SWT.PUSH);
item_delete.setText("Delete Item");
// when click "Delete Item", delete selected item
item_delete.addListener(SWT.Selection, new Listener() {
public void handleEvent(Event e) {
TreeItem[] selection = tree.getSelection();
int index = tree.indexOf(selection[0]);
for (int i=0; i < selection.length; i++){
selection[i].dispose();
}
// item deleted need new selection
TreeItem[] items = tree.getItems();
if (items.length != 0) {
if (index > items.length-1) {
// it would be better to select an item closer to the deleted item?
view.setData((TreeItemData) items[items.length-1].getData());
tree.setSelection(items[items.length-1]);
} else {
view.setData((TreeItemData) items[index].getData());
tree.setSelection(items[index]);
}
}
}
}); // end item_delete
menu.setLocation(event.x, event.y);
menu.setVisible(true);
while (!menu.isDisposed() && menu.isVisible()) {
if (!display.readAndDispatch())
display.sleep();
}
menu.dispose();
}
}); // end right click menu
// when a new treeItem is selected, update the view
tree.addListener(SWT.Selection, new Listener() {
public void handleEvent(Event event)
{
view.setData((TreeItemData) event.item.getData());
}
}); // end update view with tree item data
// when the tree looses focus make sure things are in order
tree.addListener(SWT.FocusOut, new Listener() {
public void handleEvent(Event event) {
TreeItem[] selection = tree.getSelection();
// no item selected - view data is ambigous, possible data loss
if (selection.length == 0) {
MessageBox messageBox = new MessageBox(shell, SWT.ICON_ERROR);
messageBox.setText("Possible Loss of Data.");
messageBox.setMessage("Think about what you did to cause the view data and the tree selection to get out of sync, and decide how you want your program to behave!");
messageBox.open();
//*/
TreeItem[] items = tree.getItems();
if (items.length != 0) {
view.setData((TreeItemData) items[0].getData());
tree.setSelection(items[0]);
} else {
// no items in view?! you can't delete the last item...
TreeItemData myData = new TreeItemData();
myData.Name = "Item" + count++;
myData.field1 = myData.Name + " Data";
TreeItem item = new TreeItem(tree, SWT.NONE);
item.setText(myData.Name);
item.setData(myData);
view.setData((TreeItemData) item.getData());
tree.setSelection(item);
}
//*/
}
}
}); // end tree loose focus
// setup DragSource
DragSource source = new DragSource(tree, DND.DROP_COPY);
source.setTransfer(new Transfer[] { TreeItemDataTransfer.getInstance() });
source.addDragListener(new DragSourceAdapter() {
public void dragStart(DragSourceEvent event) {
TreeItem[] selection = tree.getSelection();
if (selection.length > 0 && selection[0].getData() != null) {
event.doit = true;
sourceTreeItem = selection[0];
} else {
event.doit = false;
}
} // end dargStart
public void dragSetData(DragSourceEvent event) {
if (TreeItemDataTransfer.getInstance().isSupportedType(event.dataType))
event.data = sourceTreeItem.getData();
} // end dargSetData
public void dragFinished(DragSourceEvent event) {
if (event.doit) {
sourceTreeItem.dispose();
}
sourceTreeItem = null;
} // end dragFinished
}); // end DragSource
// setup DropTarget
DropTarget target = new DropTarget(tree, DND.DROP_COPY);
target.setTransfer(new Transfer[] {TreeItemDataTransfer.getInstance() });
target.addDropListener(new DropTargetAdapter() {
public void dragEnter(DropTargetEvent event) {
event.detail = DND.DROP_COPY;
} // end dragEnter
public void dragOver(DropTargetEvent event) {
event.feedback = DND.FEEDBACK_SCROLL;
// if the drop target is a specific item in the tree
if (event.item != null) {
TreeItem item = (TreeItem) event.item;
Point pt = display.map(null, tree, event.x, event.y);
Rectangle bounds = item.getBounds();
// give visual cue of drop location to user
if (pt.y < bounds.y + bounds.height/2) {
event.feedback |= DND.FEEDBACK_INSERT_BEFORE;
} else {
event.feedback |= DND.FEEDBACK_INSERT_AFTER;
}
} else {
// set event.item to last item in list & set feedback to after
}
} // end dragOver
public void drop(DropTargetEvent event) {
try {
if (event.data == null) {
event.detail = DND.DROP_NONE;
return;
}
TreeItem newItem;
// if the dropTarget is a specific item in the tree
if (event.item != null) {
TreeItem selection = (TreeItem) event.item;
Point pt = display.map(null, tree, event.x, event.y);
Rectangle bounds = selection.getBounds();
//TreeItem[] items = tree.getItems();
// find index of selection
int index = tree.indexOf(selection);
// insert newItem at index
if (pt.y < bounds.y + bounds.height/2) {
// insert before
newItem = new TreeItem(tree, SWT.NONE, index);
} else {
// insert after
newItem = new TreeItem(tree, SWT.NONE, index+1);
}
} else {
// no specific item selected, drop at the end
newItem = new TreeItem(tree, SWT.NONE);
}
TreeItemData myType = (TreeItemData) event.data;
newItem.setText(myType.Name);
newItem.setData(myType);
// set selection otherwise view data gets out of sync
tree.setSelection(newItem);
} catch (RuntimeException e) {
e.printStackTrace();
}
} // end drop
}); // end DropTarget
// write view data back to tree - see CompositePane.Update()
tree.addListener(SWT.Arm, new Listener() {
public void handleEvent(Event event) {
tree.getSelection()[0].setData((TreeItemData) view.getData());
}
});
// wrap it up
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch())
display.sleep();
}
display.dispose();
}
} // class LeftTabs
class TreeItemData {
// all the data to be held by each treeItem
String Name;
String field1;
} // new members must be explicitly handled in nativeToJava & javaToNative
// Transfer class for handling DND of TreeItemData
class TreeItemDataTransfer extends ByteArrayTransfer {
private static final String TreeItemData_TRANSFER_NAME = "TreeItemData_TRANSFER";
private static final int TreeItemData_TRANSFER_ID = registerType (TreeItemData_TRANSFER_NAME);
private static TreeItemDataTransfer instance = new TreeItemDataTransfer();
public static TreeItemDataTransfer getInstance() {
return instance;
}
protected String[] getTypeNames() {
return new String[] { TreeItemData_TRANSFER_NAME };
}
protected int[] getTypeIds() {
return new int[] {TreeItemData_TRANSFER_ID};
}
public void javaToNative (Object object, TransferData transferData) {
if (object == null || !(object instanceof TreeItemData))
return;
TreeItemData myType = (TreeItemData) object;
if (isSupportedType(transferData)) {
try {
ByteArrayOutputStream stream = new ByteArrayOutputStream();
DataOutputStream out = new DataOutputStream(stream);
// write out each member in your custom dataType
out.writeUTF(myType.Name);
out.writeUTF(myType.field1);
out.close();
super.javaToNative(stream.toByteArray(), transferData);
} catch (IOException e) {
e.printStackTrace();
}
}
} // end javaToNative
public Object nativeToJava (TransferData transferData) {
if (isSupportedType(transferData)) {
byte[] buffer = (byte[]) super.nativeToJava(transferData);
if (buffer == null)
return null;
TreeItemData myType = new TreeItemData();
try {
ByteArrayInputStream stream = new ByteArrayInputStream(buffer);
DataInputStream in = new DataInputStream(stream);
// read in each member in your custom dataType
myType.Name = in.readUTF();
myType.field1 = in.readUTF();
in.close();
} catch (IOException e) {
e.printStackTrace();
return null;
}
return myType;
} else {
return null;
}
} // end nativetoJava
} // end TreeItemDataTransfer
// Composite widget for defining the right hand "view"
class CompositePane extends Composite {
// local TreeItemData, to keep track of changes
static TreeItemData viewData;
// declarations of pane view widgets
static Text text;
public CompositePane (Composite c) {
// setup layout of the pane
super(c, SWT.NONE);
this.setLayout(new FillLayout());
// put widgets in the pane
text = new Text(this, SWT.BORDER | SWT.MULTI | SWT.WRAP);
// add a loose focus listener to EVERY *EDITABLE* widget
text.addListener(SWT.Deactivate, new Listener()
{
public void handleEvent(Event event)
{
// sync changes in view back to dataum
Update();
}
});
} // CompositePane constructor
public void setData (TreeItemData n)
{
viewData = n;
// populate the pane's elements with the viewData
text.setText(viewData.field1);
}
// update viewData, then notify listener that it should sync to the tree
public void Update() {
viewData.field1 = text.getText();
this.notifyListeners(SWT.Modify, new Event());
}
public TreeItemData getData()
{
return viewData;
}
} // class CompositePane
I'm not happy with my options for displaying code in google blogger, and more than a little disappointed in this temporary solution. Expect a blog post to come out of that. I'm also trying to work on a secure crossplatform Snergy config that's giving me trouble so it may be worth a post.
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