uk.ac.starlink.ttools.plot

Class Drawing

java.lang.Object

uk.ac.starlink.ttools.plot.Drawing

All Implemented Interfaces:

Pixellator

public class Drawing
extends Object
implements Pixellator

Provides drawing primitives on a pixel map. This is a bit like a Graphics, but renders only to a one-bit-per-pixel bitmap. After drawings have been done, the object can be used as a Pixellator to get a list of the pixels which have been hit at least once by one of the drawing methods called during the life of the object. Pixels will not be repeated in this list.

The drawing methods are intended to be as efficient as possible. Bounds checking is done, so it is generally not problematic (or inefficient) to attempt drawing operations with coordinates far outside the drawing's range.

Since:

20 Mar 2007

Author:

Mark Taylor

Constructor Summary

Constructors

Constructor and Description
Drawing(Rectangle bounds) Constructs a drawing with given pixel bounds.

Method Summary

Modifier and Type	Method and Description
void	addPixel(int x, int y) Adds a single pixel to the list of pixels which have been plotted.
void	addPixels(Pixellator pixellator) Adds all the pixels from the given Pixellator to this drawing.
static Pixellator	combinePixellators(Pixellator[] pixers) Combines an array of given pixellators to produce a single one which iterates over all the pixels.
void	draw(Shape shape) Draws the outline of an arbitrary shape.
void	drawEllipse(int x0, int y0, int ax, int ay, int bx, int by) Draws the outline of an ellipse with no restrictions on the alignment of its axes.
void	drawLine(int x0, int y0, int x1, int y1) Draws a straight line between two points.
void	drawOval(int x, int y, int width, int height) Draws the outline of an ellipse with horizontal/vertical axes.
void	fill(Shape shape) Fills an arbitrary shape.
void	fillEllipse(int x0, int y0, int ax, int ay, int bx, int by) Fills an ellipse with no restrictions on the alignment of its axes.
void	fillOval(int x, int y, int width, int height) Fills an ellipse with horizontal/vertical axes.
void	fillRect(int x, int y, int width, int height) Fills a rectangle.
Rectangle	getBounds() Returns a copy of the bounding rectangle for this pixellator.
int	getX() Returns the X value for the current point.
int	getY() Returns the Y value for the current point.
boolean	next() Moves to the next point in the sequence.
void	start() Makes this object ready to iterate.

Methods inherited from class java.lang.Object

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

Constructor Detail

Drawing

public Drawing(Rectangle bounds)

Constructs a drawing with given pixel bounds.

Parameters:

bounds - rectangle giving the region in which pixels may be plotted

Method Detail

getBounds

public Rectangle getBounds()

Description copied from interface: Pixellator

Returns a copy of the bounding rectangle for this pixellator. All points iterated over by this object will fall within this rectangle. If this object has no points, null may be returned.

Specified by:

getBounds in interface Pixellator

Returns:

bounds

addPixel

public void addPixel(int x,
                     int y)

Adds a single pixel to the list of pixels which have been plotted. Calling it with coordinates which have already been plotted, or which are outside this drawing's bounds, has no effect.

Parameters:

x - X coordinate

y - Y coordinate

drawLine

public void drawLine(int x0,
                     int y0,
                     int x1,
                     int y1)

Draws a straight line between two points.

Parameters:

x0 - X coordinate of first point

y0 - Y coordinate of first point

x1 - X coordinate of second point

y1 - Y coordinate of second point

See Also:

Graphics.drawLine(int, int, int, int)

fillRect

public void fillRect(int x,
                     int y,
                     int width,
                     int height)

Fills a rectangle.

Parameters:

x - X coordinate of top left corner

y - Y coordinate of top left corner

width - width

height - height

See Also:

Graphics.fillRect(int, int, int, int)

drawOval

public void drawOval(int x,
                     int y,
                     int width,
                     int height)

Draws the outline of an ellipse with horizontal/vertical axes.

Parameters:

x - X coordinate of top left corner of enclosing rectangle

y - Y coordinate of top left corner of enclosing rectangle

width - width of enclosing rectangle

height - height of enclosing rectangle

See Also:

Graphics.drawOval(int, int, int, int)

fillOval

public void fillOval(int x,
                     int y,
                     int width,
                     int height)

Fills an ellipse with horizontal/vertical axes.

Parameters:

x - X coordinate of top left corner of enclosing rectangle

y - Y coordinate of top left corner of enclosing rectangle

width - width of enclosing rectangle

height - height of enclosing rectangle

See Also:

Graphics.drawOval(int, int, int, int)

drawEllipse

public void drawEllipse(int x0,
                        int y0,
                        int ax,
                        int ay,
                        int bx,
                        int by)

Draws the outline of an ellipse with no restrictions on the alignment of its axes.

Parameters:

x0 - X coordinate of ellipse centre

y0 - Y coordinate of ellipse centre

ax - X component of semi-major (or -minor) axis

ay - Y component of semi-major (or -minor) axis

bx - X component of semi-minor (or -major) axis

by - Y component of semi-minor (Or -major) axis

fillEllipse

public void fillEllipse(int x0,
                        int y0,
                        int ax,
                        int ay,
                        int bx,
                        int by)

Fills an ellipse with no restrictions on the alignment of its axes.

Parameters:

x0 - X coordinate of ellipse centre

y0 - Y coordinate of ellipse centre

ax - X component of semi-major (or -minor) axis

ay - Y component of semi-major (or -minor) axis

bx - X component of semi-minor (or -major) axis

by - Y component of semi-minor (Or -major) axis

fill

public void fill(Shape shape)

Fills an arbitrary shape.

Parameters:

shape - shape to fill

See Also:

Graphics2D.fill(java.awt.Shape)

draw

public void draw(Shape shape)

Draws the outline of an arbitrary shape. May not be that efficient.

Parameters:

shape - shape to draw

See Also:

Graphics2D.draw(java.awt.Shape)

addPixels

public void addPixels(Pixellator pixellator)

Adds all the pixels from the given Pixellator to this drawing.

Parameters:

pixellator - iterator over pixels to add

start

public void start()

Description copied from interface: Pixellator

Makes this object ready to iterate. Should be called before any call to Pixellator.next().

Specified by:

start in interface Pixellator

next

public boolean next()

Description copied from interface: Pixellator

Moves to the next point in the sequence. Must be called before any call to Pixellator.getX()/Pixellator.getY(). Returns value indicates whether there is a next point.

Specified by:

next in interface Pixellator

Returns:

next true iff there are more points

getX

public int getX()

Description copied from interface: Pixellator

Returns the X value for the current point.

Specified by:

getX in interface Pixellator

Returns:

x

getY

public int getY()

Description copied from interface: Pixellator

Returns the Y value for the current point.

Specified by:

getY in interface Pixellator

Returns:

y

combinePixellators

public static Pixellator combinePixellators(Pixellator[] pixers)

Combines an array of given pixellators to produce a single one which iterates over all the pixels. It is tempting just to provide a new Pixellator implementation which iterates over its consituent ones to do this, but that would risk returning some pixels multiple times, which we don't want.

Parameters:

pixers - array of pixellators to combine

Returns:

pixellator comprising the union of the supplied ones