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package javax.print.attribute;

import java.io.Serializable;

/**
 * Class Size2DSyntax is an abstract base class providing the common
 * implementation of all attributes denoting a size in two dimensions.
 * <P>
 * A two-dimensional size attribute's value consists of two items, the X
 * dimension and the Y dimension. A two-dimensional size attribute may be
 * constructed by supplying the two values and indicating the units in which the
 * values are measured. Methods are provided to return a two-dimensional size
 * attribute's values, indicating the units in which the values are to be
 * returned. The two most common size units are inches (in) and millimeters
 * (mm), and exported constants {@link #INCH <CODE>INCH</CODE>} and {@link #MM
 * <CODE>MM</CODE>} are provided for indicating those units.
 * <P>
 * Once constructed, a two-dimensional size attribute's value is immutable.
 * <P>
 * <B>Design</B>
 * <P>
 * A two-dimensional size attribute's X and Y dimension values are stored
 * internally as integers in units of micrometers (&#181;m), where 1 micrometer
 * = 10<SUP>-6</SUP> meter = 1/1000 millimeter = 1/25400 inch. This permits
 * dimensions to be represented exactly to a precision of 1/1000 mm (= 1
 * &#181;m) or 1/100 inch (= 254 &#181;m). If fractional inches are expressed in
 * negative powers of two, this permits dimensions to be represented exactly to
 * a precision of 1/8 inch (= 3175 &#181;m) but not 1/16 inch (because 1/16 inch
 * does not equal an integral number of &#181;m).
 * <P>
 * Storing the dimensions internally in common units of &#181;m lets two size
 * attributes be compared without regard to the units in which they were
 * created; for example, 8.5 in will compare equal to 215.9 mm, as they both are
 * stored as 215900 &#181;m. For example, a lookup service can
 * match resolution attributes based on equality of their serialized
 * representations regardless of the units in which they were created. Using
 * integers for internal storage allows precise equality comparisons to be done,
 * which would not be guaranteed if an internal floating point representation
 * were used. Note that if you're looking for U.S. letter sized media in metric
 * units, you have to search for a media size of 215.9 x 279.4 mm; rounding off
 * to an integral 216 x 279 mm will not match.
 * <P>
 * The exported constant {@link #INCH <CODE>INCH</CODE>} is actually the
 * conversion factor by which to multiply a value in inches to get the value in
 * &#181;m. Likewise, the exported constant {@link #MM <CODE>MM</CODE>} is the
 * conversion factor by which to multiply a value in mm to get the value in
 * &#181;m. A client can specify a resolution value in units other than inches
 * or mm by supplying its own conversion factor. However, since the internal
 * units of &#181;m was chosen with supporting only the external units of inch
 * and mm in mind, there is no guarantee that the conversion factor for the
 * client's units will be an exact integer. If the conversion factor isn't an
 * exact integer, resolution values in the client's units won't be stored
 * precisely.
 * <P>
 *
 * @author  Alan Kaminsky
 */
public abstract class Size2DSyntax implements Serializable, Cloneable {

    private static final long serialVersionUID = 5584439964938660530L;

    /**
     * X dimension in units of micrometers (&#181;m).
     * @serial
     */
    private int x;

    /**
     * Y dimension in units of micrometers (&#181;m).
     * @serial
     */
    private int y;

    /**
     * Value to indicate units of inches (in). It is actually the conversion
     * factor by which to multiply inches to yield &#181;m (25400).
     */
    public static final int INCH = 25400;

    /**
     * Value to indicate units of millimeters (mm). It is actually the
     * conversion factor by which to multiply mm to yield &#181;m (1000).
     */
    public static final int MM = 1000;


    /**
     * Construct a new two-dimensional size attribute from the given
     * floating-point values.
     *
     * @param  x  X dimension.
     * @param  y  Y dimension.
     * @param  units
     *     Unit conversion factor, e.g. {@link #INCH <CODE>INCH</CODE>} or
     *     {@link #MM <CODE>MM</CODE>}.
     *
     * @exception  IllegalArgumentException
     *     (Unchecked exception) Thrown if <CODE>x</CODE> < 0 or <CODE>y</CODE>
     *     < 0 or <CODE>units</CODE> < 1.
     */
    protected Size2DSyntax(float x, float y, int units) {
        if (x < 0.0f) {
            throw new IllegalArgumentException("x < 0");
        }
        if (y < 0.0f) {
            throw new IllegalArgumentException("y < 0");
        }
        if (units < 1) {
            throw new IllegalArgumentException("units < 1");
        }
        this.x = (int) (x * units + 0.5f);
        this.y = (int) (y * units + 0.5f);
    }

    /**
     * Construct a new two-dimensional size attribute from the given integer
     * values.
     *
     * @param  x  X dimension.
     * @param  y  Y dimension.
     * @param  units
     *     Unit conversion factor, e.g. {@link #INCH <CODE>INCH</CODE>} or
     *     {@link #MM <CODE>MM</CODE>}.
     *
     * @exception  IllegalArgumentException
     *   (Unchecked exception) Thrown if <CODE>x</CODE> < 0 or <CODE>y</CODE>
     *    < 0 or <CODE>units</CODE> < 1.
     */
    protected Size2DSyntax(int x, int y, int units) {
        if (x < 0) {
            throw new IllegalArgumentException("x < 0");
        }
        if (y < 0) {
            throw new IllegalArgumentException("y < 0");
        }
        if (units < 1) {
            throw new IllegalArgumentException("units < 1");
        }
        this.x = x * units;
        this.y = y * units;
    }

    /**
     * Convert a value from micrometers to some other units. The result is
     * returned as a floating-point number.
     *
     * @param  x
     *     Value (micrometers) to convert.
     * @param  units
     *     Unit conversion factor, e.g. {@link #INCH <CODE>INCH</CODE>} or
     *     {@link #MM <CODE>MM</CODE>}.
     *
     * @return  The value of <CODE>x</CODE> converted to the desired units.
     *
     * @exception  IllegalArgumentException
     *     (unchecked exception) Thrown if <CODE>units</CODE> < 1.
     */
    private static float convertFromMicrometers(int x, int units) {
        if (units < 1) {
            throw new IllegalArgumentException("units is < 1");
        }
        return ((float)x) / ((float)units);
    }

    /**
     * Get this two-dimensional size attribute's dimensions in the given units
     * as floating-point values.
     *
     * @param  units
     *     Unit conversion factor, e.g. {@link #INCH <CODE>INCH</CODE>} or
     *     {@link #MM <CODE>MM</CODE>}.
     *
     * @return  A two-element array with the X dimension at index 0 and the Y
     *          dimension at index 1.
     *
     * @exception  IllegalArgumentException
     *     (unchecked exception) Thrown if <CODE>units</CODE> < 1.
     */
    public float[] getSize(int units) {
        return new float[] {getX(units), getY(units)};
    }

    /**
     * Returns this two-dimensional size attribute's X dimension in the given
     * units as a floating-point value.
     *
     * @param  units
     *     Unit conversion factor, e.g. {@link #INCH <CODE>INCH</CODE>} or
     *     {@link #MM <CODE>MM</CODE>}.
     *
     * @return  X dimension.
     *
     * @exception  IllegalArgumentException
     *     (unchecked exception) Thrown if <CODE>units</CODE> < 1.
     */
    public float getX(int units) {
        return convertFromMicrometers(x, units);
    }

    /**
     * Returns this two-dimensional size attribute's Y dimension in the given
     * units as a floating-point value.
     *
     * @param  units
     *     Unit conversion factor, e.g. {@link #INCH <CODE>INCH</CODE>} or
     *     {@link #MM <CODE>MM</CODE>}.
     *
     * @return  Y dimension.
     *
     * @exception  IllegalArgumentException
     *     (unchecked exception) Thrown if <CODE>units</CODE> < 1.
     */
    public float getY(int units) {
        return convertFromMicrometers(y, units);
    }

    /**
     * Returns a string version of this two-dimensional size attribute in the
     * given units. The string takes the form <CODE>"<I>X</I>x<I>Y</I>
     * <I>U</I>"</CODE>, where <I>X</I> is the X dimension, <I>Y</I> is the Y
     * dimension, and <I>U</I> is the units name. The values are displayed in
     * floating point.
     *
     * @param  units
     *     Unit conversion factor, e.g. {@link #INCH <CODE>INCH</CODE>} or
     *     {@link #MM <CODE>MM</CODE>}.
     * @param  unitsName
     *     Units name string, e.g. <CODE>"in"</CODE> or <CODE>"mm"</CODE>. If
     *     null, no units name is appended to the result.
     *
     * @return  String version of this two-dimensional size attribute.
     *
     * @exception  IllegalArgumentException
     *     (unchecked exception) Thrown if <CODE>units</CODE> < 1.
     */
    public String toString(int units, String unitsName) {
        StringBuffer result = new StringBuffer();
        result.append(getX (units));
        result.append('x');
        result.append(getY (units));
        if (unitsName != null) {
            result.append(' ');
            result.append(unitsName);
        }
        return result.toString();
    }

    /**
     * Returns whether this two-dimensional size attribute is equivalent to the
     * passed in object. To be equivalent, all of the following conditions must
     * be true:
     * <OL TYPE=1>
     * <LI>
     * <CODE>object</CODE> is not null.
     * <LI>
     * <CODE>object</CODE> is an instance of class Size2DSyntax.
     * <LI>
     * This attribute's X dimension is equal to <CODE>object</CODE>'s X
     * dimension.
     * <LI>
     * This attribute's Y dimension is equal to <CODE>object</CODE>'s Y
     * dimension.
     * </OL>
     *
     * @param  object  Object to compare to.
     *
     * @return  True if <CODE>object</CODE> is equivalent to this
     *          two-dimensional size attribute, false otherwise.
     */
    public boolean equals(Object object) {
        return(object != null &&
               object instanceof Size2DSyntax &&
               this.x == ((Size2DSyntax) object).x &&
               this.y == ((Size2DSyntax) object).y);
    }

    /**
     * Returns a hash code value for this two-dimensional size attribute.
     */
    public int hashCode() {
        return (((x & 0x0000FFFF)      ) |
                ((y & 0x0000FFFF) << 16));
    }

    /**
     * Returns a string version of this two-dimensional size attribute. The
     * string takes the form <CODE>"<I>X</I>x<I>Y</I> um"</CODE>, where
     * <I>X</I> is the X dimension and <I>Y</I> is the Y dimension.
     * The values are reported in the internal units of micrometers.
     */
    public String toString() {
        StringBuffer result = new StringBuffer();
        result.append(x);
        result.append('x');
        result.append(y);
        result.append(" um");
        return result.toString();
    }

    /**
     * Returns this two-dimensional size attribute's X dimension in units of
     * micrometers (&#181;m). (For use in a subclass.)
     *
     * @return  X dimension (&#181;m).
     */
    protected int getXMicrometers(){
        return x;
    }

    /**
     * Returns this two-dimensional size attribute's Y dimension in units of
     * micrometers (&#181;m). (For use in a subclass.)
     *
     * @return  Y dimension (&#181;m).
     */
    protected int getYMicrometers() {
        return y;
    }

}
