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/*
 * Copyright © 1996-2009 GlobalMentor, Inc. 
 *
 * Licensed 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 com.globalmentor.swing.text;

import java.awt.*;
import javax.swing.text.*;

/**
 * A view that is not visible and is breakable only as a last resort.
 * @author Garret Wilson
 */
public class InvisibleView extends ZeroSpanView {

	/**
	 * Constructor which specifies an element.
	 * @param element The element this view represents.
	 */
	public InvisibleView(Element element) {
		super(element); //construct the parent class
	}

	/**
	 * Returns a boolean value that indicates whether the view is visible or not.
	 * 
	 * Hidden views always return false.
	 * 
	 * @return false, indicating that the view is not visible.
	 */
	public boolean isVisible() {
		return false;
	}

	/**
	 * Determines how attractive a break opportunity in this view is. An invisible view is designed to be breakable, but only as a last resort; this
	 * implementation therefore returns BadBreakWeight+1. This prevents invisible views from coming between and breaking visible views that should
	 * not be separated (the first has page-break-after: avoid, for example).
	 * @param axis The breaking axis, either View.X_AXIS or View.Y_AXIS.
	 * @param pos The potential location of the start of the broken view (>=0).
	 * @param len Specifies the relative length from pos where a potential break is desired (>=0).
	 * @return The weight, which should be a value between View.ForcedBreakWeight and View.BadBreakWeight.
	 */
	public int getBreakWeight(int axis, float pos, float len) {
		return BadBreakWeight + 1; //an invisible view is the worst possible break there could be TODO is it really *that* bad? maybe it should be GoodBreakWeight-1
	}

	/**
	 * Provides a way to determine the next visually represented model location at which one might place a caret.
	 * 
	 * As this view is always hidden, it always returns -1.
	 * 
	 * @param pos The position to convert (>=0).
	 * @param a The allocated region in which to render.
	 * @param direction The direction from the current position that can be thought of as the arrow keys typically found on a keyboard. This will be one of the
	 *          following values:
	 *          
	 *          SwingConstants.WEST
	 *          SwingConstants.EAST
	 *          SwingConstants.NORTH
	 *          SwingConstants.SOUTH
	 *          
	 * @return The location within the model that best represents the next location visual position. This version always returns -1.
	 * @throws BadLocationException
	 * @throws IllegalArgumentException if direction doesn't have one of the legal values above
	 */
	public int getNextVisualPositionFrom(int pos, Position.Bias b, Shape a, int direction, Position.Bias[] biasRet) throws BadLocationException {
		return -1; //show that no visual positions are valid in a hidden view
	}

}