org.tinfour.utils

Class AxisIntervals

java.lang.Object

org.tinfour.utils.AxisIntervals

public final class AxisIntervals
extends Object

Provides a utility for computing the intervals for labeling a coordinate axis in a legend or other graph.

This class is used in many of the demonstration applications supplied with the Tinfour software library. For example, it is used to select intervals for legends in color-coded surface representations. It is used to label axes in trend-line graphs. And it is also used to pick contour intervals in contour-rendering applications.

Method Summary

Modifier and Type	Method and Description
static AxisIntervals	computeIntervals(double value0, double value1, int primaryMinIntervalInPixels, int secondaryMinIntervalInPixels, int sizeInPixels) Compute the intervals over a range of values.
static AxisIntervals	computeIntervals(double value0, double value1, int primaryMinIntervalInPixels, int secondaryMinIntervalInPixels, int sizeInPixels, boolean bracketValues) Compute the intervals over a range of values.
double	getCoordinateScale() Get a multiplicative factor for scaling coordinates to pixels.
int	getIntervalMagnitude() Gets the integer power of ten corresponding to the magnitude of the primary interval.
double[]	getLabelCoordinates() Gets the coordinates for labels.
String	getLabelFormat() Get a label format that is intended to be appropriate to the magnitude of the primary interval
String[]	getLabels() Gets formatted labels for the tic coordinates.
double[][]	getTicCoordinates() Gets the coordinates for the tic marks to be added to the axis.
double	getUnitsPerPixel() Gets the scale factor for units in the value coordinate system compare to pixels.
double	getValue0() Gets the minimum value of the range used to specify the axis.
double	getValue1() Gets the maximum value of the range used to specify the axis.
boolean	isValue0Labeled() Indicates if value0 was included in the primary tic coordinates.
boolean	isValue1Labeled() Indicates if value1 was included in the primary tic coordinates.
double	mapValueToPixel(double value) Maps a value to a corresponding pixel coordinate.

Methods inherited from class java.lang.Object

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

Method Detail

getValue0

public double getValue0()

Gets the minimum value of the range used to specify the axis.

Returns:

a valid floating point value

getValue1

public double getValue1()

Gets the maximum value of the range used to specify the axis.

Returns:

a valid floating point value

isValue0Labeled

public boolean isValue0Labeled()

Indicates if value0 was included in the primary tic coordinates. This happens when value0 is an integral multiple of the primary interval.

Returns:

true if value0 is included in the tic coordinates; otherwise false

isValue1Labeled

public boolean isValue1Labeled()

Indicates if value1 was included in the primary tic coordinates. This happens when value1 is an integral multiple of the primary interval.

Returns:

true if value1 is included in the tic coordinates; otherwise false

getTicCoordinates

public double[][] getTicCoordinates()

Gets the coordinates for the tic marks to be added to the axis. The array turned may be of dimension one or two. If it is of dimension 1, only primary tic intervals are included. If it is of dimension 2, then secondary tic intervals are included. Note that the coordinates for the secondary tic marks do not overlap those of the primary intervals.

Returns:

a valid array of dimension one or two.

getLabelCoordinates

public double[] getLabelCoordinates()

Gets the coordinates for labels. This value is redundant with the primary tic coordinates/

Returns:

a valid array

getLabels

public String[] getLabels()

Gets formatted labels for the tic coordinates.

Returns:

a valid array

getLabelFormat

public String getLabelFormat()

Get a label format that is intended to be appropriate to the magnitude of the primary interval

Returns:

a valid Java format string

getCoordinateScale

public double getCoordinateScale()

Get a multiplicative factor for scaling coordinates to pixels.

Returns:

a valid floating point value

computeIntervals

public static AxisIntervals computeIntervals(double value0,
                                             double value1,
                                             int primaryMinIntervalInPixels,
                                             int secondaryMinIntervalInPixels,
                                             int sizeInPixels)

Compute the intervals over a range of values. This method attempts to select the the finest real-valued intervals that map to a pixel scale larger than the specified limits and confirm to nice "human friendly" values.

Parameters:

value0 - the minimum value to be represented.

value1 - the maximum value to be represented.

primaryMinIntervalInPixels - the minimum spacing allowed for the primary interval

secondaryMinIntervalInPixels - the minimum space allowed for the secondary interval

sizeInPixels - the overall size of the area for labeling, i..e$#46; the length of a horizontal axis or the height of a vertical axis

Returns:

if successful, a valid instance; otherwise, a null.

computeIntervals

public static AxisIntervals computeIntervals(double value0,
                                             double value1,
                                             int primaryMinIntervalInPixels,
                                             int secondaryMinIntervalInPixels,
                                             int sizeInPixels,
                                             boolean bracketValues)

Compute the intervals over a range of values. This method attempts to select the the finest real-valued intervals that map to a pixel scale larger than the specified limits and confirm to nice "human friendly" values.

Parameters:

value0 - the minimum value to be represented.

value1 - the maximum value to be represented.

primaryMinIntervalInPixels - the minimum spacing allowed for the primary interval

secondaryMinIntervalInPixels - the minimum space allowed for the secondary interval

sizeInPixels - the overall size of the area for labeling, i..e$#46; the length of a horizontal axis or the height of a vertical axis

bracketValues - true if the computed interval must fully bracket the input values; false if bracketing is optional.

Returns:

if successful, a valid instance; otherwise, a null.

mapValueToPixel

public double mapValueToPixel(double value)

Maps a value to a corresponding pixel coordinate. Value0 maps to zero. Value1 maps to (value1-value0)/unitsPerPixel.

Parameters:

value - the value to be mapped.

Returns:

a valid floating point value

getIntervalMagnitude

public int getIntervalMagnitude()

Gets the integer power of ten corresponding to the magnitude of the primary interval. For example, if the primary interval were 0.2, the interval magnitude would be -1.

Returns:

an integer

getUnitsPerPixel

public double getUnitsPerPixel()

Gets the scale factor for units in the value coordinate system compare to pixels. Useful for creating affine transforms.

Returns:

a finite, non-zero floating point value;