@Override
  public void duplicate() {
    Selection sel = canvas.getSelection();
    int n = sel.getSelected().size();
    List<CanvasObject> select = new ArrayList<CanvasObject>(n);
    List<CanvasObject> clones = new ArrayList<CanvasObject>(n);
    for (CanvasObject o : sel.getSelected()) {
      if (o.canRemove()) {
        CanvasObject copy = o.clone();
        copy.translate(10, 10);
        clones.add(copy);
        select.add(copy);
      } else {
        select.add(o);
      }
    }

    if (!clones.isEmpty()) {
      canvas
          .getProject()
          .doAction(
              new SelectionAction(
                  canvas,
                  Strings.getter("duplicateSelectionAction"),
                  null,
                  clones,
                  select,
                  null,
                  null));
    }
  }
  @Override
  public void delete() {
    Selection sel = canvas.getSelection();
    int n = sel.getSelected().size();
    List<CanvasObject> select = new ArrayList<CanvasObject>(n);
    List<CanvasObject> remove = new ArrayList<CanvasObject>(n);
    Location anchorLocation = null;
    Direction anchorFacing = null;
    for (CanvasObject o : sel.getSelected()) {
      if (o.canRemove()) {
        remove.add(o);
      } else {
        select.add(o);
        if (o instanceof AppearanceAnchor) {
          AppearanceAnchor anchor = (AppearanceAnchor) o;
          anchorLocation = anchor.getLocation();
          anchorFacing = anchor.getFacing();
        }
      }
    }

    if (!remove.isEmpty()) {
      canvas
          .getProject()
          .doAction(
              new SelectionAction(
                  canvas,
                  Strings.getter("deleteSelectionAction"),
                  remove,
                  null,
                  select,
                  anchorLocation,
                  anchorFacing));
    }
  }
  @Override
  public void paste() {
    ClipboardContents clip = Clipboard.get();
    Collection<CanvasObject> contents = clip.getElements();
    List<CanvasObject> add = new ArrayList<CanvasObject>(contents.size());
    for (CanvasObject o : contents) {
      add.add(o.clone());
    }
    if (add.isEmpty()) return;

    // find how far we have to translate shapes so that at least one of the
    // pasted shapes doesn't match what's already in the model
    Collection<CanvasObject> raw = canvas.getModel().getObjectsFromBottom();
    MatchingSet<CanvasObject> cur = new MatchingSet<CanvasObject>(raw);
    int dx = 0;
    while (true) {
      // if any shapes in "add" aren't in canvas, we are done
      boolean allMatch = true;
      for (CanvasObject o : add) {
        if (!cur.contains(o)) {
          allMatch = false;
          break;
        }
      }
      if (!allMatch) break;

      // otherwise translate everything by 10 pixels and repeat test
      for (CanvasObject o : add) {
        o.translate(10, 10);
      }
      dx += 10;
    }

    Location anchorLocation = clip.getAnchorLocation();
    if (anchorLocation != null && dx != 0) {
      anchorLocation = anchorLocation.translate(dx, dx);
    }

    canvas
        .getProject()
        .doAction(
            new SelectionAction(
                canvas,
                Strings.getter("pasteClipboardAction"),
                null,
                add,
                add,
                anchorLocation,
                clip.getAnchorFacing()));
  }