logarithmicaxis.java

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/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2005, 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * --------------------
 * LogarithmicAxis.java
 * --------------------
 * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
 *
 * Original Author:  Michael Duffy / Eric Thomas;
 * Contributor(s):   David Gilbert (for Object Refinery Limited);
 *                   David M. O'Donnell;
 *                   Scott Sams;
 *
 * $Id: LogarithmicAxis.java,v 1.11 2005/05/19 13:58:11 mungady Exp $
 *
 * Changes
 * -------
 * 14-Mar-2002 : Version 1 contributed by Michael Duffy (DG);
 * 19-Apr-2002 : drawVerticalString() is now drawRotatedString() in
 *               RefineryUtilities (DG);
 * 23-Apr-2002 : Added a range property (DG);
 * 15-May-2002 : Modified to be able to deal with negative and zero values (via
 *               new 'adjustedLog10()' method);  occurrences of "Math.log(10)"
 *               changed to "LOG10_VALUE"; changed 'intValue()' to
 *               'longValue()' in 'refreshTicks()' to fix label-text value
 *               out-of-range problem; removed 'draw()' method; added
 *               'autoRangeMinimumSize' check; added 'log10TickLabelsFlag'
 *               parameter flag and implementation (ET);
 * 25-Jun-2002 : Removed redundant import (DG);
 * 25-Jul-2002 : Changed order of parameters in ValueAxis constructor (DG);
 * 16-Jul-2002 : Implemented support for plotting positive values arbitrarily
 *               close to zero (added 'allowNegativesFlag' flag) (ET).
 * 05-Sep-2002 : Updated constructor reflecting changes in the Axis class (DG);
 * 02-Oct-2002 : Fixed errors reported by Checkstyle (DG);
 * 08-Nov-2002 : Moved to new package com.jrefinery.chart.axis (DG);
 * 22-Nov-2002 : Bug fixes from David M. O'Donnell (DG);
 * 14-Jan-2003 : Changed autoRangeMinimumSize from Number --> double (DG);
 * 20-Jan-2003 : Removed unnecessary constructors (DG);
 * 26-Mar-2003 : Implemented Serializable (DG);
 * 08-May-2003 : Fixed plotting of datasets with lower==upper bounds when
 *               'minAutoRange' is very small; added 'strictValuesFlag'
 *               and default functionality of throwing a runtime exception
 *               if 'allowNegativesFlag' is false and any values are less
 *               than or equal to zero; added 'expTickLabelsFlag' and
 *               changed to use "1e#"-style tick labels by default
 *               ("10^n"-style tick labels still supported via 'set'
 *               method); improved generation of tick labels when range of
 *               values is small; changed to use 'NumberFormat.getInstance()'
 *               to create 'numberFormatterObj' (ET);
 * 14-May-2003 : Merged HorizontalLogarithmicAxis and
 *               VerticalLogarithmicAxis (DG);
 * 29-Oct-2003 : Added workaround for font alignment in PDF output (DG);
 * 07-Nov-2003 : Modified to use new NumberTick class (DG);
 * 08-Apr-2004 : Use numberFormatOverride if set - see patch 930139 (DG);
 * 11-Jan-2005 : Removed deprecated code in preparation for 1.0.0 release (DG);
 * 21-Apr-2005 : Added support for upper and lower margins; added
 *               get/setAutoRangeNextLogFlag() methods and changed
 *               default to 'autoRangeNextLogFlag'==false (ET);
 * 22-Apr-2005 : Removed refreshTicks() and fixed names and parameters for
 *               refreshHorizontalTicks() & refreshVerticalTicks();
 *               changed javadoc on setExpTickLabelsFlag() to specify
 *               proper default (ET);
 * 22-Apr-2005 : Renamed refreshHorizontalTicks --> refreshTicksHorizontal
 *               (and likewise the vertical version) for consistency with
 *               other axis classes (DG);
 *
 */

package org.jfree.chart.axis;

import java.awt.Graphics2D;
import java.awt.geom.Rectangle2D;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.List;

import org.jfree.chart.plot.Plot;
import org.jfree.chart.plot.ValueAxisPlot;
import org.jfree.data.Range;
import org.jfree.ui.RectangleEdge;
import org.jfree.ui.TextAnchor;

/**
 * A numerical axis that uses a logarithmic scale.
 *
 * @author Michael Duffy
 */
public class LogarithmicAxis extends NumberAxis {

    /** For serialization. */
    private static final long serialVersionUID = 2502918599004103054L;
    
    /** Useful constant for log(10). */
    public static final double LOG10_VALUE = Math.log(10.0);

    /** Smallest arbitrarily-close-to-zero value allowed. */
    public static final double SMALL_LOG_VALUE = 1e-100;

    /** Flag set true to allow negative values in data. */
    protected boolean allowNegativesFlag = false;

    /** Flag set true make axis throw exception if any values are
      * <= 0 and 'allowNegativesFlag' is false. */
    protected boolean strictValuesFlag = true;

    /** Number formatter for generating numeric strings. */
    protected final NumberFormat numberFormatterObj
        = NumberFormat.getInstance();

    /** Flag set true for "1e#"-style tick labels. */
    protected boolean expTickLabelsFlag = false;

    /** Flag set true for "10^n"-style tick labels. */
    protected boolean log10TickLabelsFlag = false;

    /** True to make 'autoAdjustRange()' select "10^n" values. */
    protected boolean autoRangeNextLogFlag = false;

    /** Helper flag for log axis processing. */
    protected boolean smallLogFlag = false;

    /**
     * Creates a new axis.
     *
     * @param label  the axis label.
     */
    public LogarithmicAxis(String label) {
        super(label);
        setupNumberFmtObj();      //setup number formatter obj
    }

    /**
     * Sets the 'allowNegativesFlag' flag; true to allow negative values
     * in data, false to be able to plot positive values arbitrarily close to
     * zero.
     *
     * @param flgVal  the new value of the flag.
     */
    public void setAllowNegativesFlag(boolean flgVal) {
        this.allowNegativesFlag = flgVal;
    }

    /**
     * Returns the 'allowNegativesFlag' flag; true to allow negative values
     * in data, false to be able to plot positive values arbitrarily close
     * to zero.
     *
     * @return The flag.
     */
    public boolean getAllowNegativesFlag() {
        return this.allowNegativesFlag;
    }

    /**
     * Sets the 'strictValuesFlag' flag; if true and 'allowNegativesFlag'
     * is false then this axis will throw a runtime exception if any of its
     * values are less than or equal to zero; if false then the axis will
     * adjust for values less than or equal to zero as needed.
     *
     * @param flgVal true for strict enforcement.
     */
    public void setStrictValuesFlag(boolean flgVal) {
        this.strictValuesFlag = flgVal;
    }

    /**
     * Returns the 'strictValuesFlag' flag; if true and 'allowNegativesFlag'
     * is false then this axis will throw a runtime exception if any of its
     * values are less than or equal to zero; if false then the axis will
     * adjust for values less than or equal to zero as needed.
     *
     * @return <code>true</code> if strict enforcement is enabled.
     */
    public boolean getStrictValuesFlag() {
        return this.strictValuesFlag;
    }

    /**
     * Sets the 'expTickLabelsFlag' flag.  If the 'log10TickLabelsFlag'
     * is false then this will set whether or not "1e#"-style tick labels
     * are used.  The default is to use regular numeric tick labels.
     *
     * @param flgVal true for "1e#"-style tick labels, false for
     * log10 or regular numeric tick labels.
     */
    public void setExpTickLabelsFlag(boolean flgVal) {
        this.expTickLabelsFlag = flgVal;
        setupNumberFmtObj();             //setup number formatter obj
    }

    /**
     * Returns the 'expTickLabelsFlag' flag.
     *
     * @return <code>true</code> for "1e#"-style tick labels,
     *         <code>false</code> for log10 or regular numeric tick labels.
     */
    public boolean getExpTickLabelsFlag() {
      return this.expTickLabelsFlag;
    }

    /**
     * Sets the 'log10TickLabelsFlag' flag.  The default value is false.
     *
     * @param flag true for "10^n"-style tick labels, false for "1e#"-style
     * or regular numeric tick labels.
     */
    public void setLog10TickLabelsFlag(boolean flag) {
        this.log10TickLabelsFlag = flag;
    }

    /**
     * Returns the 'log10TickLabelsFlag' flag.
     *
     * @return <code>true</code> for "10^n"-style tick labels,
     *         <code>false</code> for "1e#"-style or regular numeric tick
     *         labels.
     */
    public boolean getLog10TickLabelsFlag() {
        return this.log10TickLabelsFlag;
    }

    /**
     * Sets the 'autoRangeNextLogFlag' flag.  This determines whether or
     * not the 'autoAdjustRange()' method will select the next "10^n"
     * values when determining the upper and lower bounds.  The default
     * value is false.
     *
     * @param flag <code>true</code> to make the 'autoAdjustRange()'
     * method select the next "10^n" values, <code>false</code> to not.
     */
    public void setAutoRangeNextLogFlag(boolean flag) {
        this.autoRangeNextLogFlag = flag;
    }

    /**
     * Returns the 'autoRangeNextLogFlag' flag.
     *
     * @return <code>true</code> if the 'autoAdjustRange()' method will
     * select the next "10^n" values, <code>false</code> if not.
     */
    public boolean getAutoRangeNextLogFlag() {
        return this.autoRangeNextLogFlag;
    }

    /**
     * Overridden version that calls original and then sets up flag for
     * log axis processing.
     *
     * @param range  the new range.
     */
    public void setRange(Range range) {
        super.setRange(range);      // call parent method
        setupSmallLogFlag();        // setup flag based on bounds values
    }

    /**
     * Sets up flag for log axis processing.  Set true if negative values
     * not allowed and the lower bound is between 0 and 10.
     */
    protected void setupSmallLogFlag() {
        // set flag true if negative values not allowed and the
        // lower bound is between 0 and 10:
        double lowerVal = getRange().getLowerBound();
        this.smallLogFlag
            = (!this.allowNegativesFlag && lowerVal < 10.0 && lowerVal > 0.0);
    }

    /**
     * Sets up the number formatter object according to the
     * 'expTickLabelsFlag' flag.
     */
    protected void setupNumberFmtObj() {
        if (this.numberFormatterObj instanceof DecimalFormat) {
            //setup for "1e#"-style tick labels or regular
            // numeric tick labels, depending on flag:
            ((DecimalFormat) this.numberFormatterObj).applyPattern(
                this.expTickLabelsFlag ? "0E0" : "0.###"
            );
        }
    }

    /**
     * Returns the log10 value, depending on if values between 0 and
     * 1 are being plotted.  If negative values are not allowed and
     * the lower bound is between 0 and 10 then a normal log is
     * returned; otherwise the returned value is adjusted if the
     * given value is less than 10.
     *
     * @param val the value.
     *
     * @return log<sub>10</sub>(val).
     */
    protected double switchedLog10(double val) {
        return this.smallLogFlag ? Math.log(val)
                / LOG10_VALUE : adjustedLog10(val);
    }

    /**
     * Returns an adjusted log10 value for graphing purposes.  The first
     * adjustment is that negative values are changed to positive during
     * the calculations, and then the answer is negated at the end.  The
     * second is that, for values less than 10, an increasingly large
     * (0 to 1) scaling factor is added such that at 0 the value is
     * adjusted to 1, resulting in a returned result of 0.
     *
     * @param val  value for which log10 should be calculated.
     *
     * @return An adjusted log<sub>10</sub>(val).
     */
    public double adjustedLog10(double val) {
        boolean negFlag = (val < 0.0);
        if (negFlag) {
            val = -val;          // if negative then set flag and make positive
        }
        if (val < 10.0) {                // if < 10 then
            val += (10.0 - val) / 10;    //increase so 0 translates to 0
        }
        //return value; negate if original value was negative:
        return negFlag ? -(Math.log(val) / LOG10_VALUE)