net.talvi.puffinplot

Class Util

java.lang.Object

net.talvi.puffinplot.Util

public class Util
extends java.lang.Object

This class collects miscellaneous, general-purpose utility functions which are useful to PuffinPlot.

Constructor Summary

Constructors

Constructor and Description
Util()

Method Summary

Modifier and Type	Method and Description
static java.lang.String	calculateSHA1(java.io.File file) Calculate the SHA-1 digest of a file and return it as an upper-case hexadecimal string.
static java.awt.geom.Line2D	clipLineToRectangle(java.awt.geom.Line2D line, java.awt.geom.Rectangle2D r) Clips a line to a supplied rectangle.
static void	downloadUrlToFile(java.lang.String url, java.nio.file.Path outputPath) Downloads data from a URL and saves it to a file.
static java.awt.geom.Rectangle2D	envelope(java.util.Collection<java.awt.geom.Point2D> points) Returns the rectangular envelope for the supplied points.
static java.nio.file.Path	getAppDataDirectory() Return a directory where PuffinPlot can store files for "internal" use.
static java.text.DecimalFormatSymbols	getDecimalFormatSymbols() Return symbols for formatting decimal numbers for on-screen display.
static java.util.BitSet	numberRangeStringToBitSet(java.lang.String input, int limit) Converts a string specification of number ranges to a corresponding BitSet.
static double	parseDoubleSafely(java.lang.String s) A wrapper around Double.parseDouble which returns a default value of 0 if the supplied string cannot be parsed.
static boolean	runningOnOsX() Reports whether the JVM is running on Mac OS X.
static java.awt.geom.Line2D	scaleLine(java.awt.geom.Line2D line, double scale) Scales a line around its midpoint.
static java.lang.Double	tryToParseDouble(java.awt.Component parentWindow, java.lang.String s) Try to parse a string to a Double object; if a NumberFormatException is thrown, show an error dialog and return null.
static java.lang.Integer	tryToParseInteger(java.awt.Component parentWindow, java.lang.String s) Try to parse a string to an Integer object; if a NumberFormatException is thrown, show an error dialog and return null.
static void	zipDirectory(java.nio.file.Path dir, java.nio.file.Path zipFile) Create a zip file from the contents of a directory.

Methods inherited from class java.lang.Object

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

Constructor Detail

Util

public Util()

Method Detail

numberRangeStringToBitSet

public static java.util.BitSet numberRangeStringToBitSet(java.lang.String input,
                                                         int limit)

Converts a string specification of number ranges to a corresponding BitSet. The specification is of the form commonly encountered in Print dialog boxes: a sequence of comma-separated units. Each unit can be either an integer (meaning that the corresponding item should be selected) or two integers separated by a hyphen (-) character (meaning that all items in the corresponding range should be selected). Example inputs and outputs are shown below.

Example specifications

1	1
1,3	101
4-6	000111
4-6,8-10,10,11,15-16	0001110111100011
1-4,3-5,10,12-14,17	11111000010111001

Note that the range specifications are one-based (the first item is specified by 1, not 0) but the BitSet output is zero-based.

Since an error in the specification string might result in an impractically large bitset, this method also takes a limit argument; no bits will be set beyond the specified limit.

Parameters:

input - a specification string

limit - upper limit for bits to set; limit-1 will be the highest possible set bit

Returns:

a bit-set representation of the specified range

clipLineToRectangle

public static java.awt.geom.Line2D clipLineToRectangle(java.awt.geom.Line2D line,
                                                       java.awt.geom.Rectangle2D r)

Clips a line to a supplied rectangle.

Parameters:

line - a line (null if none)

r - a clipping rectangle (null if none)

Returns:

the line, as clipped to the supplied rectangle, if the two overlap; null if they do not overlap; null if either of the input parameters were null

parseDoubleSafely

public static double parseDoubleSafely(java.lang.String s)

A wrapper around Double.parseDouble which returns a default value of 0 if the supplied string cannot be parsed. (Double.parseDouble, in contrast, throws a NumberFormatException.)

Parameters:

s - A string representation of a floating-point number.

Returns:

A double with a value corresponding to the supplied string, or 0 if the string could not be interpreted as a floating-point number.

getAppDataDirectory

public static java.nio.file.Path getAppDataDirectory()
                                              throws java.io.IOException

Return a directory where PuffinPlot can store files for "internal" use. The directory is created if necessary. On *nix systems, a dot-prefixed directory in the user's home directory is used. On Windows, a subdirectory of the LOCALAPPDATA directory is used.

Returns:

Path to a directory for application data

Throws:

java.io.IOException - if there was an error creating or finding the directory

envelope

public static java.awt.geom.Rectangle2D envelope(java.util.Collection<java.awt.geom.Point2D> points)

Returns the rectangular envelope for the supplied points. This is the smallest rectangle which contains all the points.

Parameters:

points - a set of points

Returns:

the smallest rectangle which contains all the points, or null if no points were supplied

scaleLine

public static java.awt.geom.Line2D scaleLine(java.awt.geom.Line2D line,
                                             double scale)

Scales a line around its midpoint. Given a line with length L, returns a line with length scale*L, with the same midpoint and direction as the provided line.

Parameters:

line - the line to scale

scale - the scale factor

Returns:

the scaled line

zipDirectory

public static void zipDirectory(java.nio.file.Path dir,
                                java.nio.file.Path zipFile)
                         throws java.io.IOException

Create a zip file from the contents of a directory. If the directory is on a filesystem and filestore supporting Posix file permissions, these will be preserved in the zip file.

Parameters:

dir - the directory to archive

zipFile - the path of the zip file to create

Throws:

java.io.IOException - if there was an exception while reading the directory contents or writing the zip file

calculateSHA1

public static java.lang.String calculateSHA1(java.io.File file)
                                      throws java.io.IOException,
                                             java.security.NoSuchAlgorithmException

Calculate the SHA-1 digest of a file and return it as an upper-case hexadecimal string.

Parameters:

file - the file for which to calculate the digest

Returns:

the SHA-1 digest

Throws:

java.io.IOException - if there is an error reading the file

java.security.NoSuchAlgorithmException - if the SHA-1 algorithm is not available

downloadUrlToFile

public static void downloadUrlToFile(java.lang.String url,
                                     java.nio.file.Path outputPath)
                              throws java.io.IOException

Downloads data from a URL and saves it to a file.

Parameters:

url - the URL to use as a data source

outputPath - the file to which to save the data found at the URL

Throws:

java.io.IOException - if an error occurs while downloading or saving

runningOnOsX

public static boolean runningOnOsX()

Reports whether the JVM is running on Mac OS X.

Returns:

true if this PuffinApp is running on Mac OS X

tryToParseInteger

public static java.lang.Integer tryToParseInteger(java.awt.Component parentWindow,
                                                  java.lang.String s)

Try to parse a string to an Integer object; if a NumberFormatException is thrown, show an error dialog and return null.

Parameters:

parentWindow - parent for the error dialog

s - string to parse

Returns:

value of string, or null if not parseable as integer

tryToParseDouble

public static java.lang.Double tryToParseDouble(java.awt.Component parentWindow,
                                                java.lang.String s)

Try to parse a string to a Double object; if a NumberFormatException is thrown, show an error dialog and return null.

Parameters:

parentWindow - parent for the error dialog

s - string to parse

Returns:

value of string, or null if not parseable as double

getDecimalFormatSymbols

public static java.text.DecimalFormatSymbols getDecimalFormatSymbols()

Return symbols for formatting decimal numbers for on-screen display. The purpose of this method is to serve (eventually) as a single source from which global settings for the preferred minus sign (ASCII hyphen-minus or "proper" Unicode minus) and exponent separator ("e" or "E") can be retrieved.

Returns:

decimal format symbols for on-screen display