taxeditor-editor/src/main/java/eu/etaxonomy/taxeditor/editor/WidgetTransfer.java

   1 package eu.etaxonomy.taxeditor.editor;
   2
   3 import org.eclipse.swt.dnd.ByteArrayTransfer;
   4 import org.eclipse.swt.dnd.TransferData;
   5 import org.eclipse.swt.widgets.Widget;
   6
   7 /**
   8  * For drag and drop - a drag widget with this transfer type can only be dropped onto
   9  *  a drop widget with the same type.
  10  *
  11  * @author p.ciardelli
  12  *
  13  */
  14 public class WidgetTransfer extends ByteArrayTransfer {
  15
  16         private static final String WIDGETTYPENAME = "widget_type";
  17         private static final int WIDGETTYPEID = registerType (WIDGETTYPENAME);
  18         private static final WidgetTransfer INSTANCE = new WidgetTransfer();
  19
  20         /*
  21          * The object associated with this transfer event
  22          */
  23         private Widget widget;
  24
  25         /*
  26          * Returns the singleton
  27          */
  28         public static WidgetTransfer getInstance() {
  29                 return INSTANCE;
  30         }
  31         /*
  32          * Set transfer data for local use
  33          */
  34         public void setWidget(Widget widget) {
  35                 this.widget = widget;
  36         }
  37         /*
  38          * Returns the local transfer data
  39          */
  40         public Widget getWidget() {
  41                 return widget;
  42         }
  43
  44         /*
  45          * The type ID is used to identify this transfer
  46          */
  47         @Override
  48         protected int[] getTypeIds() {
  49                 return new int[] { WIDGETTYPEID };
  50         }
  51
  52         @Override
  53         protected String[] getTypeNames() {
  54                 return new String[] { WIDGETTYPENAME } ;
  55         }
  56
  57         @Override
  58         protected void javaToNative(Object object, TransferData transferData) {
  59                 // No encoding needed since this is a hardcoded string read and written
  60                 // in the same process.
  61                 // See nativeToJava below
  62                 byte[] check = WIDGETTYPENAME.getBytes();
  63                 super.javaToNative(check, transferData);
  64         }
  65
  66         @Override
  67         protected Object nativeToJava(TransferData transferData) {
  68                 Object result = super.nativeToJava(transferData);
  69                 if (isInvalidNativeType(result)) {
  70                         throw new RuntimeException(); //$NON-NLS-1$
  71                 }
  72                 return widget;
  73         }
  74
  75         private boolean isInvalidNativeType(Object result) {
  76                 // No encoding needed since this is a hardcoded string read and written
  77                 // in the same process.
  78                 // See javaToNative above
  79                 return !(result instanceof byte[])
  80                                 || !WIDGETTYPENAME.equals(new String((byte[]) result));
  81         }
  82 }