/* ====================================================================
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
==================================================================== */

package org.apache.poi.xdgf.usermodel.shape;

import java.awt.geom.AffineTransform;

import org.apache.poi.xdgf.usermodel.XDGFShape;

/**
 * Used to iterate through shapes
 *
 * To change the behavior of a particular visitor, you can override either
 * accept() or getAcceptor() [preferred]
 *
 * If accept() or visit() throw StopVisitingThisBranch, the iteration will not
 * visit subshapes of the shape.
 */
public abstract class ShapeVisitor {

    protected ShapeVisitorAcceptor _acceptor;

    public ShapeVisitor() {
        _acceptor = getAcceptor();
    }
    
    /**
     * Is only called on construction of the visitor, allows
     * mixing visitors and acceptors
     */
    protected ShapeVisitorAcceptor getAcceptor() {
        return new ShapeVisitorAcceptor() {
            @Override
            public boolean accept(XDGFShape shape) {
                return !shape.isDeleted();
            }
        };
    }

    public void setAcceptor(ShapeVisitorAcceptor acceptor) {
        _acceptor = acceptor;
    }

    public boolean accept(XDGFShape shape) {
        return _acceptor.accept(shape);
    }

    /**
     * @param shape
     *            Current shape
     * @param globalTransform
     *            A transform that can convert the shapes points to global
     *            coordinates
     * @param level
     *            Level in the tree (0 is topmost, 1 is next level...
     */
    public abstract void visit(XDGFShape shape,
            AffineTransform globalTransform, int level);

}