Source Code : Drag and Drop example snippet: drag leaf items in a tree

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Drag and Drop example snippet: drag leaf items in a tree

/*
 * Drag and Drop example snippet: drag leaf items in a tree
 *
 * For a list of all SWT example snippets see
 * http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/platform-swt-home/dev.html#snippets
 */
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.DragSourceListener;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.TextTransfer;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeItem;

public class Snippet91 {

  public static void main(String[] args) {

    final Display display = new Display();
    final Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());
    final Tree tree = new Tree(shell, SWT.BORDER);
    for (int i = 0; i < 3; i++) {
      TreeItem item = new TreeItem(tree, SWT.NONE);
      item.setText("item " + i);
      for (int j = 0; j < 3; j++) {
        TreeItem subItem = new TreeItem(item, SWT.NONE);
        subItem.setText("item " + i + " " + j);
        for (int k = 0; k < 3; k++) {
          TreeItem subsubItem = new TreeItem(subItem, SWT.NONE);
          subsubItem.setText("item " + i + " " + j + " " + k);
        }
      }
    }

    Transfer[] types = new Transfer[] { TextTransfer.getInstance() };
    int operations = DND.DROP_MOVE | DND.DROP_COPY | DND.DROP_LINK;

    final DragSource source = new DragSource(tree, operations);
    source.setTransfer(types);
    final TreeItem[] dragSourceItem = new TreeItem[1];
    source.addDragListener(new DragSourceListener() {
      public void dragStart(DragSourceEvent event) {
        TreeItem[] selection = tree.getSelection();
        if (selection.length > 0 && selection[0].getItemCount() == 0) {
          event.doit = true;
          dragSourceItem[0] = selection[0];
        } else {
          event.doit = false;
        }
      };

      public void dragSetData(DragSourceEvent event) {
        event.data = dragSourceItem[0].getText();
      }

      public void dragFinished(DragSourceEvent event) {
        if (event.detail == DND.DROP_MOVE)
          dragSourceItem[0].dispose();
        dragSourceItem[0] = null;
      }
    });

    DropTarget target = new DropTarget(tree, operations);
    target.setTransfer(types);
    target.addDropListener(new DropTargetAdapter() {
      public void dragOver(DropTargetEvent event) {
        event.feedback = DND.FEEDBACK_EXPAND | DND.FEEDBACK_SCROLL;
        if (event.item != null) {
          TreeItem item = (TreeItem) event.item;
          Point pt = display.map(null, tree, event.x, event.y);
          Rectangle bounds = item.getBounds();
          if (pt.y < bounds.y + bounds.height / 3) {
            event.feedback |= DND.FEEDBACK_INSERT_BEFORE;
          } else if (pt.y > bounds.y + 2 * bounds.height / 3) {
            event.feedback |= DND.FEEDBACK_INSERT_AFTER;
          } else {
            event.feedback |= DND.FEEDBACK_SELECT;
          }
        }
      }

      public void drop(DropTargetEvent event) {
        if (event.data == null) {
          event.detail = DND.DROP_NONE;
          return;
        }
        String text = (String) event.data;
        if (event.item == null) {
          TreeItem item = new TreeItem(tree, SWT.NONE);
          item.setText(text);
        } else {
          TreeItem item = (TreeItem) event.item;
          Point pt = display.map(null, tree, event.x, event.y);
          Rectangle bounds = item.getBounds();
          TreeItem parent = item.getParentItem();
          if (parent != null) {
            TreeItem[] items = parent.getItems();
            int index = 0;
            for (int i = 0; i < items.length; i++) {
              if (items[i] == item) {
                index = i;
                break;
              }
            }
            if (pt.y < bounds.y + bounds.height / 3) {
              TreeItem newItem = new TreeItem(parent, SWT.NONE,
                  index);
              newItem.setText(text);
            } else if (pt.y > bounds.y + 2 * bounds.height / 3) {
              TreeItem newItem = new TreeItem(parent, SWT.NONE,
                  index + 1);
              newItem.setText(text);
            } else {
              TreeItem newItem = new TreeItem(item, SWT.NONE);
              newItem.setText(text);
            }

          } else {
            TreeItem[] items = tree.getItems();
            int index = 0;
            for (int i = 0; i < items.length; i++) {
              if (items[i] == item) {
                index = i;
                break;
              }
            }
            if (pt.y < bounds.y + bounds.height / 3) {
              TreeItem newItem = new TreeItem(tree, SWT.NONE,
                  index);
              newItem.setText(text);
            } else if (pt.y > bounds.y + 2 * bounds.height / 3) {
              TreeItem newItem = new TreeItem(tree, SWT.NONE,
                  index + 1);
              newItem.setText(text);
            } else {
              TreeItem newItem = new TreeItem(item, SWT.NONE);
              newItem.setText(text);
            }
          }

        }
      }
    });

    shell.setSize(400, 400);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    display.dispose();
  }
}

           
       

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