* A two-dimensional size attribute's value consists of two items, the {@code X} * dimension and the {@code 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 INCH} and {@link #MM MM} are * provided for indicating those units. *
* Once constructed, a two-dimensional size attribute's value is immutable. *
* Design *
* A two-dimensional size attribute's {@code X} and {@code Y} dimension values * are stored internally as integers in units of micrometers (µm), where 1 * micrometer = 10-6 meter = 1/1000 millimeter = 1/25400 inch. This * permits dimensions to be represented exactly to a precision of 1/1000 mm (= 1 * µm) or 1/100 inch (= 254 µm). 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 µm) but not 1/16 inch (because 1/16 inch * does not equal an integral number of µm). *
* Storing the dimensions internally in common units of µm 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 µm. 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 {@code 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. *
* The exported constant {@link #INCH INCH} is actually the conversion factor by
* which to multiply a value in inches to get the value in µm. Likewise,
* the exported constant {@link #MM MM} is the conversion factor by which to
* multiply a value in mm to get the value in µm. 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 µm 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.
*
* @author Alan Kaminsky
*/
public abstract class Size2DSyntax implements Serializable, Cloneable {
/**
* Use serialVersionUID from JDK 1.4 for interoperability.
*/
private static final long serialVersionUID = 5584439964938660530L;
/**
* {@code X} dimension in units of micrometers (µm).
*
* @serial
*/
private int x;
/**
* {@code Y} dimension in units of micrometers (µm).
*
* @serial
*/
private int y;
/**
* Value to indicate units of inches (in). It is actually the conversion
* factor by which to multiply inches to yield µm (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 µm (1000).
*/
public static final int MM = 1000;
/**
* Construct a new two-dimensional size attribute from the given
* floating-point values.
*
* @param x {@code X} dimension
* @param y {@code Y} dimension
* @param units unit conversion factor, e.g. {@link #INCH INCH} or
* {@link #MM MM}
* @throws IllegalArgumentException if {@code x < 0} or {@code y < 0} or
* {@code units < 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 {@code X} dimension
* @param y {@code Y} dimension
* @param units unit conversion factor, e.g. {@link #INCH INCH} or
* {@link #MM MM}
* @throws IllegalArgumentException if {@code x < 0} or {@code y < 0} or
* {@code units < 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 INCH} or
* {@link #MM MM}
* @return the value of {@code x} converted to the desired units
* @throws IllegalArgumentException if {@code units < 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 INCH} or
* {@link #MM MM}
* @return a two-element array with the {@code X} dimension at index 0 and
* the {@code Y} dimension at index 1
* @throws IllegalArgumentException if {@code units < 1}
*/
public float[] getSize(int units) {
return new float[] {getX(units), getY(units)};
}
/**
* Returns this two-dimensional size attribute's {@code X} dimension in the
* given units as a floating-point value.
*
* @param units unit conversion factor, e.g. {@link #INCH INCH} or
* {@link #MM MM}
* @return {@code X} dimension
* @throws IllegalArgumentException if {@code units < 1}
*/
public float getX(int units) {
return convertFromMicrometers(x, units);
}
/**
* Returns this two-dimensional size attribute's {@code Y} dimension in the
* given units as a floating-point value.
*
* @param units unit conversion factor, e.g. {@link #INCH INCH} or
* {@link #MM MM}
* @return {@code Y} dimension
* @throws IllegalArgumentException if {@code units < 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 "XxY
* U", where X is the {@code X} dimension, Y is
* the {@code Y} dimension, and U is the units name. The values are
* displayed in floating point.
*
* @param units unit conversion factor, e.g. {@link #INCH INCH} or
* {@link #MM MM}
* @param unitsName units name string, e.g. {@code in} or {@code mm}. If
* {@code null}, no units name is appended to the result
* @return {@code String} version of this two-dimensional size attribute
* @throws IllegalArgumentException if {@code units < 1}
*/
public String toString(int units, String unitsName) {
StringBuilder result = new StringBuilder();
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:
*
"XxY um", where X
* is the {@code X} dimension and Y is the {@code Y} dimension. The
* values are reported in the internal units of micrometers.
*/
public String toString() {
StringBuilder result = new StringBuilder();
result.append(x);
result.append('x');
result.append(y);
result.append(" um");
return result.toString();
}
/**
* Returns this two-dimensional size attribute's {@code X} dimension in
* units of micrometers (µm). (For use in a subclass.)
*
* @return {@code X} dimension (µm)
*/
protected int getXMicrometers(){
return x;
}
/**
* Returns this two-dimensional size attribute's {@code Y} dimension in
* units of micrometers (µm). (For use in a subclass.)
*
* @return {@code Y} dimension (µm)
*/
protected int getYMicrometers() {
return y;
}
}