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/* ResolutionSyntax.java --

   Copyright (C) 2003, 2004, 2005  Free Software Foundation, Inc.

This file is part of GNU Classpath.

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package javax.print.attribute;

import java.io.Serializable;

/**

 * <code>ResolutionSyntax</code> is the abstract base class of all attribute

 * classes which provide a resolution as value (e.g. printer resolution).

 * <p>

 * A <code>ResolutionSyntax</code> instance consists of two integer values

 * describing the resolution in feed and cross feed direction. The units of

 * the given values is determined by two defined constants:

 * <ul>

 * <li>DPCM - dots per centimeter</li>

 * <li>DPI - dots per inch</li>

 * </ul>

 * </p>

 * <p>

 * A resolutions attribute is constructed by two values for the resolution and

 * one of the two constants defining the actual units of the given values.

 * </p>

 * <p>

 * There are different methods provided to return the resolution values in

 * either of the both units and to compare if a resolution is less than or

 * equal to a given other resolution attribute.

 * </p>

 * <p>

 * <b>Internal storage:</b><br>

 * The resolutions are stored internally as dots per 100 inches (dphi). The

 * values of the provided constants for dots per inch (value 100) and dots

 * per centimeter (value 254) are used as conversion factors to the internal

 * storage units. To get the internal dphi values a multiplication of a given

 * resolution value with its units constant value is needed. Retrieving the

 * resolution for specific units is done by dividing the internal stored

 * value through the units constant value. Clients are therefore able to

 * provide their own resolution units by supplying other conversion factors.

 * Subclasses of <code>ResolutionSyntax</code> have access to the internal

 * resolution values through the protected methods

 * {@link #getCrossFeedResolutionDphi()} and {@link #getFeedResolutionDphi()}.

 * </p>

 *

 * @author Michael Koch (konqueror@gmx.de)

 */

public abstract class ResolutionSyntax

  implements Cloneable, Serializable

{

  private static final long serialVersionUID = 2706743076526672017L;

  /**

   * Constant for units of dots per centimeter.

   */

  public static final int DPCM = 254;

  /**

   * Constant for units of dots per inch

   */

  public static final int DPI = 100;

  private int crossFeedResolution;

  private int feedResolution;

  /**

   * Creates a <code>ResolutionSyntax</code> object with the given arguments.

   *

   * @param crossFeedResolution the cross feed resolution

   * @param feedResolution the feed resolution

   * @param units the unit to use (e.g. {@link #DPCM} or {@link #DPI})

   *

   * @exception IllegalArgumentException if preconditions fail

   */

  public ResolutionSyntax(int crossFeedResolution, int feedResolution,

                          int units)

  {

    if (crossFeedResolution < 1

        || feedResolution < 1

        || units < 1)

      throw new IllegalArgumentException("no argument may be less than 1");

    this.crossFeedResolution = crossFeedResolution * units;

    this.feedResolution = feedResolution * units;

  }

  /**

   * Tests if the given object is equal to this object.

   *

   * @param obj the object to test

   *

   * @return <code>true</code> if both objects are equal,

   * <code>false</code> otherwise.

   */

  public boolean equals(Object obj)

  {

    if(! (obj instanceof ResolutionSyntax))

      return false;

    ResolutionSyntax tmp = (ResolutionSyntax) obj;

    return (crossFeedResolution == tmp.getCrossFeedResolutionDphi()

            && feedResolution == tmp.getFeedResolutionDphi());

  }

  /**

   * Returns the cross feed resolution for the given units.

   *

   * @param units the unit to use (e.g. {@link #DPCM} or {@link #DPI})

   * @return The resolution for the given units.

   *

   * @exception IllegalArgumentException if units < 1

   */

  public int getCrossFeedResolution(int units)

  {

    if (units < 1)

      throw new IllegalArgumentException("units may not be less then 1");

    return crossFeedResolution / units;

  }

  /**

   * Returns the raw cross feed resolution in dots per 100 inches.

   *

   * @return The raw resolution.

   */

  protected int getCrossFeedResolutionDphi()

  {

    return crossFeedResolution;

  }

  /**

   * Returns the feed resolution for the given units.

   *

   * @param units the unit to use (e.g. {@link #DPCM} or {@link #DPI})

   * @return The resolution for the given units.

   *

   * @exception IllegalArgumentException if units < 1

   */

  public int getFeedResolution(int units)

  {

    if (units < 1)

      throw new IllegalArgumentException("units may not be less then 1");

    return feedResolution / units;

  }

  /**

   * Returns the raw feed resolution in dots per 100 inches.

   *

   * @return The raw resolution.

   */

  protected int getFeedResolutionDphi()

  {

    return feedResolution;

  }

  /**

   * Returns the resolution as two field array. Index 0 is the cross feed

   * resolution, index 1 the feed resolution.

   *

   * @param units the units to use

   *

   * @return The array with the resolutions.

   */

  public int[] getResolution(int units)

  {

    int[] resolution = new int[2];

    resolution[0] = getCrossFeedResolution(units);

    resolution[1] = getFeedResolution(units);

    return resolution;

  }

  /**

   * Returns the hashcode for this object.

   *

   * @return The hashcode.

   */

  public int hashCode()

  {

    return crossFeedResolution + feedResolution;

  }

  /**

   * Checks if the given resolution attribute is a lower or equal

   * to this resolution object.

   *

   * @param other the resolution to check against

   *

   * @return <code>true</code> if other resolution attribute describes

   * a lower or equal resolution, <code>false</code> otherwise.

   */

  public boolean lessThanOrEquals(ResolutionSyntax other)

  {

    if (other == null)

      throw new NullPointerException("other may not be null");

    return (crossFeedResolution <= other.getCrossFeedResolutionDphi()

            && feedResolution <= other.getFeedResolutionDphi());

  }

  /**

   * Returns the string representation for this object.

   * <p>

   * The returned string is in the form "CxF dphi" with C standing

   * for the cross feed and F for the feed direction resolution.

   * Units used are dots per 100 inches (dphi).

   * </p>

   * @return The string representation.

   */

  public String toString()

  {

    return toString(1, "dphi");

  }

  /**

   * Returns the string representation for this object.

   * <p>

   * The returned string is in the form "CxF U" with C standing

   * for the cross feed and F for the feed direction resolution.

   * U denotes the units name if one is supplied.

   * </p>

   *

   * @param units the units to use

   * @param unitsName the name of the units. If <code>null</code>

   * it is ommitted from the string representation.

   *

   * @return The string representation.

   */

  public String toString(int units, String unitsName)

  {

    if (unitsName == null)

      return getCrossFeedResolution(units) + "x" + getFeedResolution(units);

    return ("" + getCrossFeedResolution(units)

            + "x" + getFeedResolution(units)

            + " " + unitsName);

  }

}