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//
// $Id: CssOpacity.java,v 1.4 2010-01-05 13:49:54 ylafon Exp $
// From Sijtsche de Jong ([email protected])
//
// (c) COPYRIGHT 1995-2000  World Wide Web Consortium (MIT, INRIA, Keio University)
// Please first read the full copyright statement at
// http://www.w3.org/Consortium/Legal/copyright-software-19980720

package org.w3c.css.properties.css3;

import org.w3c.css.parser.CssStyle;
import org.w3c.css.properties.css.CssProperty;
import org.w3c.css.util.ApplContext;
import org.w3c.css.util.InvalidParamException;
import org.w3c.css.util.Util;
import org.w3c.css.values.CssExpression;
import org.w3c.css.values.CssIdent;
import org.w3c.css.values.CssNumber;
import org.w3c.css.values.CssOperator;
import org.w3c.css.values.CssValue;

/**
 * 
 * Value: < alphavalue> || inherit

 * Initial:1

 * Applies to:all elements

 * Inherited:no

 * Percentages:no

 * Media::visual
 * 

 * This property sets the opacity of an element.
 * 
 * 
 * 
 * H1 { opacity: 0}
 * 
 * 
 */

public class CssOpacity extends CssProperty implements CssOperator {

	String opaclevel;

	ApplContext ac;

	/**
	 * Create a new CssOpacity
	 */
	public CssOpacity() {
		CssNumber cssnum = new CssNumber((float) 1.0);
		opaclevel = cssnum.toString();
	}

	/**
	 * Create a new CssOpacity
	 * 
	 * @param expression
	 *            The expression for this property
	 * @exception InvalidParamException
	 *                Values are incorrect
	 */
	public CssOpacity(ApplContext ac, CssExpression expression, boolean check)
			throws InvalidParamException {
		this.ac = ac;
		setByUser(); // tell this property is set by the user
		CssValue val = expression.getValue();

		if (val instanceof CssNumber) {

			CssNumber cssnum = new CssNumber(clampedValue(ac, ((CssNumber) val)
					.getValue()));
			opaclevel = cssnum.toString();
			expression.next();
		} else if (val instanceof CssIdent) {
			if (val.equals(inherit)) {
				opaclevel = "inherit";
				expression.next();
			} else {
				throw new InvalidParamException("value", val.toString(),
						getPropertyName(), ac);
			}
		} else {
			throw new InvalidParamException("value", val.toString(),
					getPropertyName(), ac);
		}
	}

	public CssOpacity(ApplContext ac, CssExpression expression)
			throws InvalidParamException {
		this(ac, expression, false);
	}

	/**
	 * Brings all values back between 0 and 1
	 * 
	 * @param opac
	 *            The value to be modified if necessary
	 */
	private float clampedValue(ApplContext ac, float opac) {
		if (opac < 0 || opac > 1) {
			ac.getFrame().addWarning("out-of-range", Util.displayFloat(opac));
			return ((opac < 0) ? 0 : 1);
		} else
			return (opac);
	}

	/**
	 * Add this property to the CssStyle.
	 * 
	 * @param style
	 *            The CssStyle
	 */
	public void addToStyle(ApplContext ac, CssStyle style) {
		if (((Css3Style) style).cssOpacity != null)
			style.addRedefinitionWarning(ac, this);
		((Css3Style) style).cssOpacity = this;
	}

	/**
	 * Get this property in the style.
	 * 
	 * @param style
	 *            The style where the property is
	 * @param resolve
	 *            if true, resolve the style to find this property
	 */
	public CssProperty getPropertyInStyle(CssStyle style, boolean resolve) {
		if (resolve) {
			return ((Css3Style) style).getOpacity();
		} else {
			return ((Css3Style) style).cssOpacity;
		}
	}

	/**
	 * Compares two properties for equality.
	 * 
	 * @param value
	 *            The other property.
	 */
	public boolean equals(CssProperty property) {
		return (property instanceof CssOpacity && opaclevel
				.equals(((CssOpacity) property).opaclevel));
	}

	/**
	 * Returns the name of this property
	 */
	public String getPropertyName() {
		return "opacity";
	}

	/**
	 * Returns the value of this property
	 */
	public Object get() {
		return opaclevel;
	}

	/**
	 * Returns true if this property is "softly" inherited
	 */
	public boolean isSoftlyInherited() {
		return opaclevel.equals("inherit");
	}

	/**
	 * Returns a string representation of the object
	 */
	public String toString() {
		return opaclevel;
	}

	/**
	 * Is the value of this property a default value It is used by all macro for
	 * the function print
	 */
	public boolean isDefault() {
		CssNumber cssnum = new CssNumber(ac, (float) 1.0);
		return opaclevel == cssnum.toString();
	}

}