net.alantea.swing.list.ExchangeableListTransfertHandler Maven / Gradle / Ivy

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package net.alantea.swing.list;

import java.awt.Component;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.dnd.DragSource;
import java.io.IOException;
import java.util.Objects;

import javax.swing.DefaultListModel;
import javax.swing.JComponent;
import javax.swing.JList;
import javax.swing.TransferHandler;

@SuppressWarnings("serial")
public class ExchangeableListTransfertHandler extends TransferHandler
{
   protected final DataFlavor localObjectFlavor;
   protected int[] indices;
   protected int addIndex = -1; // Location where items were added
   protected int addCount; // Number of items added.

   public ExchangeableListTransfertHandler()
   {
      super();
      localObjectFlavor = new DataFlavor(Object[].class, "items");
   }

   @Override
   protected Transferable createTransferable(JComponent c)
   {
      @SuppressWarnings("unchecked")
      JList source = (JList) c;
      c.getRootPane().getGlassPane().setVisible(true);

      indices = source.getSelectedIndices();
      Object[] transferedObjects = source.getSelectedValuesList().toArray(new Object[0]);
      return new Transferable()
      {
         @Override
         public DataFlavor[] getTransferDataFlavors()
         {
            return new DataFlavor[] { localObjectFlavor };
         }

         @Override
         public boolean isDataFlavorSupported(DataFlavor flavor)
         {
            return Objects.equals(localObjectFlavor, flavor);
         }

         @Override
         public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException, IOException
         {
            if (isDataFlavorSupported(flavor))
            {
               return transferedObjects;
            }
            else
            {
               throw new UnsupportedFlavorException(flavor);
            }
         }
      };
   }

   @Override
   public boolean canImport(TransferSupport info)
   {
      return info.isDrop() && info.isDataFlavorSupported(localObjectFlavor);
   }

   @Override
   public int getSourceActions(JComponent c)
   {
      Component glassPane = c.getRootPane().getGlassPane();
      glassPane.setCursor(DragSource.DefaultMoveDrop);
      return MOVE; // COPY_OR_MOVE;
   }

   @SuppressWarnings("unchecked")
   @Override
   public boolean importData(TransferSupport info)
   {
      TransferHandler.DropLocation tdl = info.getDropLocation();
      if (!canImport(info) || !(tdl instanceof JList.DropLocation))
      {
         return false;
      }

      JList.DropLocation dl = (JList.DropLocation) tdl;
      JList target = (JList) info.getComponent();
      DefaultListModel listModel = (DefaultListModel) target.getModel();
      int max = listModel.getSize();
      int index = dl.getIndex();
      index = index < 0 ? max : index; // If it is out of range, it is appended to the end
      index = Math.min(index, max);

      addIndex = index;

      try
      {
         Object[] values = (Object[]) info.getTransferable().getTransferData(localObjectFlavor);
         for (int i = 0; i < values.length; i++)
         {
            int idx = index++;
            listModel.add(idx, (T) values[i]);
            target.addSelectionInterval(idx, idx);
         }
         addCount = values.length;
         return true;
      }
      catch (UnsupportedFlavorException | IOException ex)
      {
         ex.printStackTrace();
      }

      return false;
   }

   @Override
   protected void exportDone(JComponent c, Transferable data, int action)
   {
      c.getRootPane().getGlassPane().setVisible(false);
      cleanup(c, action == MOVE);
   }

   private void cleanup(JComponent c, boolean remove)
   {
      if (remove && Objects.nonNull(indices))
      {
         if (addCount > 0)
         {
            for (int i = 0; i < indices.length; i++)
            {
               if (indices[i] >= addIndex)
               {
                  indices[i] += addCount;
               }
            }
         }
         @SuppressWarnings("unchecked")
         JList source = (JList) c;
         DefaultListModel model = (DefaultListModel) source.getModel();
         for (int i = indices.length - 1; i >= 0; i--)
         {
            model.remove(indices[i]);
         }
      }

      indices = null;
      addCount = 0;
      addIndex = -1;
   }
}