A number formatter for logarithmic values. This formatter does not support parsing.
/*
* JFreeChart : a free chart library for the Java(tm) platform
*
*
* (C) Copyright 2000-2009, by Object Refinery Limited and Contributors.
*
* Project Info: http://www.jfree.org/jfreechart/index.html
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc.
* in the United States and other countries.]
*
* --------------
* LogFormat.java
* --------------
* (C) Copyright 2007-2009, by Object Refinery Limited and Contributors.
*
* Original Author: David Gilbert (for Object Refinery Limited);
* Contributor(s): -;
*
* Changes
* -------
* 02-Aug-2007 : Version 1 (DG);
* 19-Feb-2008 : Implemented equals() and clone(), and added new powerLabel
* attribute as per Feature Request 1886036 (DG);
* 14-Jan-2009 : Added default constructor, and accessor methods for
* exponent formatter (DG);
*
*/
import java.text.DecimalFormat;
import java.text.FieldPosition;
import java.text.NumberFormat;
import java.text.ParsePosition;
/**
* A number formatter for logarithmic values. This formatter does not support
* parsing.
*
* @since 1.0.7
*/
public class LogFormat extends NumberFormat {
/** The log base value. */
private double base;
/** The natural logarithm of the base value. */
private double baseLog;
/** The label for the log base (for example, "e"). */
private String baseLabel;
/**
* The label for the power symbol.
*
* @since 1.0.10
*/
private String powerLabel;
/** A flag that controls whether or not the base is shown. */
private boolean showBase;
/** The number formatter for the exponent. */
private NumberFormat formatter = new DecimalFormat("0.0#");
/**
* Creates a new instance using base 10.
*
* @since 1.0.13
*/
public LogFormat() {
this(10.0, "10", true);
}
/**
* Creates a new instance.
*
* @param base the base.
* @param baseLabel the base label (<code>null</code> not permitted).
* @param showBase a flag that controls whether or not the base value is
* shown.
*/
public LogFormat(double base, String baseLabel, boolean showBase) {
this(base, baseLabel, "^", showBase);
}
/**
* Creates a new instance.
*
* @param base the base.
* @param baseLabel the base label (<code>null</code> not permitted).
* @param powerLabel the power label (<code>null</code> not permitted).
* @param showBase a flag that controls whether or not the base value is
* shown.
*
* @since 1.0.10
*/
public LogFormat(double base, String baseLabel, String powerLabel,
boolean showBase) {
if (baseLabel == null) {
throw new IllegalArgumentException("Null 'baseLabel' argument.");
}
if (powerLabel == null) {
throw new IllegalArgumentException("Null 'powerLabel' argument.");
}
this.base = base;
this.baseLog = Math.log(this.base);
this.baseLabel = baseLabel;
this.showBase = showBase;
this.powerLabel = powerLabel;
}
/**
* Returns the number format used for the exponent.
*
* @return The number format (never <code>null</code>).
*
* @since 1.0.13.
*/
public NumberFormat getExponentFormat() {
return (NumberFormat) this.formatter.clone();
}
/**
* Sets the number format used for the exponent.
*
* @param format the formatter (<code>null</code> not permitted).
*
* @since 1.0.13
*/
public void setExponentFormat(NumberFormat format) {
if (format == null) {
throw new IllegalArgumentException("Null 'format' argument.");
}
this.formatter = format;
}
/**
* Calculates the log of a given value.
*
* @param value the value.
*
* @return The log of the value.
*/
private double calculateLog(double value) {
return Math.log(value) / this.baseLog;
}
/**
* Returns a formatted representation of the specified number.
*
* @param number the number.
* @param toAppendTo the string buffer to append to.
* @param pos the position.
*
* @return A string buffer containing the formatted value.
*/
public StringBuffer format(double number, StringBuffer toAppendTo,
FieldPosition pos) {
StringBuffer result = new StringBuffer();
if (this.showBase) {
result.append(this.baseLabel);
result.append(this.powerLabel);
}
result.append(this.formatter.format(calculateLog(number)));
return result;
}
/**
* Formats the specified number as a hexadecimal string. The decimal
* fraction is ignored.
*
* @param number the number to format.
* @param toAppendTo the buffer to append to (ignored here).
* @param pos the field position (ignored here).
*
* @return The string buffer.
*/
public StringBuffer format(long number, StringBuffer toAppendTo,
FieldPosition pos) {
StringBuffer result = new StringBuffer();
if (this.showBase) {
result.append(this.baseLabel);
result.append("^");
}
result.append(this.formatter.format(calculateLog(number)));
return result;
}
/**
* Parsing is not implemented, so this method always returns
* <code>null</code>.
*
* @param source ignored.
* @param parsePosition ignored.
*
* @return Always <code>null</code>.
*/
public Number parse (String source, ParsePosition parsePosition) {
return null; // don't bother with parsing
}
/**
* Tests this formatter for equality with an arbitrary object.
*
* @param obj the object (<code>null</code> permitted).
*
* @return A boolean.
*/
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (!(obj instanceof LogFormat)) {
return false;
}
LogFormat that = (LogFormat) obj;
if (this.base != that.base) {
return false;
}
if (!this.baseLabel.equals(that.baseLabel)) {
return false;
}
if (this.baseLog != that.baseLog) {
return false;
}
if (this.showBase != that.showBase) {
return false;
}
if (!this.formatter.equals(that.formatter)) {
return false;
}
return super.equals(obj);
}
/**
* Returns a clone of this instance.
*
* @return A clone.
*/
public Object clone() {
LogFormat clone = (LogFormat) super.clone();
clone.formatter = (NumberFormat) this.formatter.clone();
return clone;
}
}
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