uk.ac.starlink.ttools.plot2.layer

Class Pixers

java.lang.Object

uk.ac.starlink.ttools.plot2.layer.Pixers

public class Pixers
extends Object

Utility class for use with Pixers.

Since:

27 Nov 2013

Author:

Mark Taylor

Field Summary

Fields

Modifier and Type	Field and Description
static Pixer	EMPTY Pixer with no pixels.

Method Summary

Modifier and Type	Method and Description
static Pixer	clip(Pixer base, Rectangle clip) Returns a clipped version of a given pixel iterator whose extent is not known.
static Pixer	clip(Pixer base, Rectangle clip, int xminBase, int xmaxBase, int yminBase, int ymaxBase) Returns a clipped version of a given pixel iterator whose extent is known.
static PixelDrawing	convolve(PixerFactory shape, PixerFactory kernel, Rectangle clip) Convolves two PixerFactories together, which can be used for instance to apply a smoothing kernel to a given shape.
static PixerFactory	copy(PixerFactory base) Returns an efficient copy of the given factory.
static Pixer	createArrayPixer(int[] xs, int[] ys, int np) Returns a new pixer that iterates over a given list of X,Y coordinates.
static Pixer	createClippedPixer(PixerFactory pfact, Rectangle clip) Returns a pixer that results from applying a clip rectangle to the output of a given PixerFactory.
static PixerFactory	createPixerCopier(Pixer pixer) Takes a given pixer and copies its data, returning an object that can issue pixers that behave the same as the original.
static Pixer	createPointsPixer(Point[] points) Returns a new pixer that iterates over an array of Points.
static Pixer	translate(Pixer base, int tx, int ty) Returns a translated version of a pixel iterator.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY

public static final Pixer EMPTY

Pixer with no pixels.

Method Detail

createArrayPixer

public static Pixer createArrayPixer(int[] xs,
                                     int[] ys,
                                     int np)

Returns a new pixer that iterates over a given list of X,Y coordinates.

Parameters:

xs - array of X values

ys - array of Y values

np - number of points (xs and ys must be at least this length)

Returns:

new pixel iterator

createPointsPixer

public static Pixer createPointsPixer(Point[] points)

Returns a new pixer that iterates over an array of Points. Iteration is done in place, so the content of these points should not be altered for the lifetime of this pixer.

Parameters:

points - point array

Returns:

pixel iterator

copy

public static PixerFactory copy(PixerFactory base)

Returns an efficient copy of the given factory. This may be suitable if it is known that many copies will be required of a Pixer.

Parameters:

base - base implementation

Returns:

new PixerFactory functionally equivalent to base implementation

createPixerCopier

public static PixerFactory createPixerCopier(Pixer pixer)

Takes a given pixer and copies its data, returning an object that can issue pixers that behave the same as the original. Since pixers are one-use iterators, this may be a useful caching operation for pixer generation methods that are potentially expensive to create and may be consumed multiple times.

Parameters:

pixer - input pixer

Returns:

factory to create copies of pixer

translate

public static Pixer translate(Pixer base,
                              int tx,
                              int ty)

Returns a translated version of a pixel iterator.

Parameters:

base - base pixel iterator

tx - offset in X direction

ty - offset in Y direction

Returns:

translated pixel iterator

clip

public static Pixer clip(Pixer base,
                         Rectangle clip)

Returns a clipped version of a given pixel iterator whose extent is not known.

Parameters:

base - base pixel iterator

clip - clipping rectangle

Returns:

clipped pixel iterator

createClippedPixer

public static Pixer createClippedPixer(PixerFactory pfact,
                                       Rectangle clip)

Returns a pixer that results from applying a clip rectangle to the output of a given PixerFactory.

Parameters:

pfact - pixer factory

clip - clipping rectangle

Returns:

pixer contiaining only points within the clip, or null if no points fall within it

clip

public static Pixer clip(Pixer base,
                         Rectangle clip,
                         int xminBase,
                         int xmaxBase,
                         int yminBase,
                         int ymaxBase)

Returns a clipped version of a given pixel iterator whose extent is known. May return null if the clipped pixer would dispense no pixels. {x,y}{min,max}Base are the extreme values of the base pixer; they do not account for the extent of a single pixel (so a single pixel at the origin would have all values set to zero).

Parameters:

base - base pixel iterator

clip - clipping rectangle

xminBase - lower limit of X values dispensed by base pixer

xmaxBase - upper limit of X values dispensed by base pixer

yminBase - lower limit of Y values dispensed by base pixer

ymaxBase - upper limit of Y values dispensed by base pixer

Returns:

clipped pixel iterator, or null if no pixels

convolve

public static PixelDrawing convolve(PixerFactory shape,
                                    PixerFactory kernel,
                                    Rectangle clip)

Convolves two PixerFactories together, which can be used for instance to apply a smoothing kernel to a given shape. The output will paint only within a given clipping region.

Parameters:

shape - first supplier of pixels

kernel - second supplier of pixels

clip - clipping rectangle for output

Returns:

convolution pixel supplier