uk.ac.starlink.ttools.plot2

Class BasicTicker

java.lang.Object

uk.ac.starlink.ttools.plot2.BasicTicker

All Implemented Interfaces:

Ticker

public abstract class BasicTicker
extends Object
implements Ticker

Partial Ticker implementation based on a rule defining a sequence of ticks. Concrete subclasses must implement a method to create a Rule suitable for a given range, and this is used to provide suitable ticks for particular circumstances, including avoiding label overlap.

Since:

17 Oct 2013

Author:

Mark Taylor

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	BasicTicker.Rule Defines a specific rule for generating major and minor axis tick marks.

Field Summary

Fields

Modifier and Type	Field and Description
static BasicTicker	LINEAR Ticker for linear axes.
static BasicTicker	LOG Ticker for logarithmic axes.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BasicTicker(boolean logFlag) Constructor.

Method Summary

Modifier and Type	Method and Description
abstract BasicTicker.Rule	createRule(double dlo, double dhi, double approxMajorCount, int adjust) Returns a new rule for labelling an axis in a given range.
static Tick[]	getMajorTicks(BasicTicker.Rule rule, double dlo, double dhi) Use a given rule to generate major ticks in a given range of coordinates.
static Tick[]	getMinorTicks(BasicTicker.Rule rule, double dlo, double dhi) Use a given rule to generate minor ticks in a given range of coordinates.
BasicTicker.Rule	getRule(double dlo, double dhi, Captioner captioner, Orientation orient, int npix, double crowding) Returns a Rule suitable for a given axis labelling job.
Tick[]	getTicks(double dlo, double dhi, boolean withMinor, Captioner captioner, Orientation orient, int npix, double crowding) Generates tick marks for labelling a plot axis.
static Caption	linearLabel(long mantissa, int exp) Generates a major tick mark label suitable for use with linear axes.
static boolean	overlaps(Tick[] ticks, Axis axis, Captioner captioner, Orientation orient) Determines whether the labels for a set of tick marks would overlap when painted on a given axis.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LINEAR

public static final BasicTicker LINEAR

Ticker for linear axes.

LOG

public static final BasicTicker LOG

Ticker for logarithmic axes.

Constructor Detail

BasicTicker

protected BasicTicker(boolean logFlag)

Constructor.

Parameters:

logFlag - true for logarithmic axis, false for linear

Method Detail

createRule

public abstract BasicTicker.Rule createRule(double dlo,
                                            double dhi,
                                            double approxMajorCount,
                                            int adjust)

Returns a new rule for labelling an axis in a given range. The tick density is determined by two parameters, approxMajorCount, which gives a baseline value for the number of ticks required over the given range, and adjust. Increasing adjust will give more major ticks, and decreasing it will give fewer ticks. Each value of adjust should result in a different tick count.

Parameters:

dlo - minimum axis data value

dhi - maximum axis data value

approxMajorCount - guide value for number of major ticks in range

adjust - adjusts density of major ticks, zero is normal

getTicks

public Tick[] getTicks(double dlo,
                       double dhi,
                       boolean withMinor,
                       Captioner captioner,
                       Orientation orient,
                       int npix,
                       double crowding)

Description copied from interface: Ticker

Generates tick marks for labelling a plot axis.

Specified by:

getTicks in interface Ticker

Parameters:

dlo - minimum axis data value

dhi - maximum axis data value

withMinor - if true minor axes are included, if false only major (labelled) ones are

captioner - caption painter

orient - label orientation

npix - number of pixels along the axis

crowding - 1 for normal tick density on the axis, lower for fewer labels, higher for more

Returns:

tick array

getRule

public BasicTicker.Rule getRule(double dlo,
                                double dhi,
                                Captioner captioner,
                                Orientation orient,
                                int npix,
                                double crowding)

Returns a Rule suitable for a given axis labelling job. This starts off by generating ticks at roughly a standard separation, guided by the crowding parameter. However, if the resulting ticks are so close as to overlap, it backs off until it finds a set of ticks that can be displayed in a tidy fashion.

Parameters:

dlo - minimum axis data value

dhi - maximum axis data value

captioner - caption painter

orient - label orientation

npix - number of pixels along the axis

crowding - 1 for normal tick density on the axis, lower for fewer labels, higher for more

Returns:

basic tick generation rule

getMajorTicks

public static Tick[] getMajorTicks(BasicTicker.Rule rule,
                                   double dlo,
                                   double dhi)

Use a given rule to generate major ticks in a given range of coordinates.

Parameters:

rule - tick generation rule

dlo - minimum axis data value

dhi - maximum axis data value

Returns:

array of major ticks

getMinorTicks

public static Tick[] getMinorTicks(BasicTicker.Rule rule,
                                   double dlo,
                                   double dhi)

Use a given rule to generate minor ticks in a given range of coordinates.

Parameters:

rule - tick generation rule

dlo - minimum axis data value

dhi - maximum axis data value

Returns:

array of minor ticks

linearLabel

public static Caption linearLabel(long mantissa,
                                  int exp)

Generates a major tick mark label suitable for use with linear axes. Some care is required assembling the label, to make sure we avoid rounding issues (like 0.999999999999). Double.toString() is not good enough.

Parameters:

mantissa - multiplier

exp - power of 10

Returns:

tick label text

overlaps

public static boolean overlaps(Tick[] ticks,
                               Axis axis,
                               Captioner captioner,
                               Orientation orient)

Determines whether the labels for a set of tick marks would overlap when painted on a given axis.

Parameters:

ticks - major tick marks

axis - axis on which the ticks will be drawn

captioner - caption painter

orient - label orientation

Returns:

true iff some of the ticks are so close to each other that their labels will overlap