uk.ac.starlink.ttools.plot2.layer

Class PixelDrawing

java.lang.Object

uk.ac.starlink.ttools.plot2.layer.PixelDrawing

All Implemented Interfaces:

PixerFactory

public class PixelDrawing
extends Object
implements PixerFactory

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 PixerFactory 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:

13 Sep 2021

Author:

Mark Taylor

Constructor Summary

Constructors

Constructor and Description
PixelDrawing(int x0, int y0, int width, int height) Constructs a drawing with bounds given explicitly.
PixelDrawing(Rectangle bounds) Constructs a drawing with bounds given by a rectangle.

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 if it is within this drawing's bounds.
void	addPixelUnchecked(int x, int y) Adds a single pixel to the list of pixels which have been plotted without bounds checking.
boolean	contains(int x, int y) Indicates whether a given position is within the bounds of this drawing.
Pixer	createPixer() Returns a Pixer that interrogates this drawing's bitmap.
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) Deprecated. may be slow for large shapes; use fillPolygon if possible
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	fillPolygon(int[] xs, int[] ys, int np) Draws a filled polygon on this drawing.
void	fillRect(int x, int y, int width, int height) Fills a rectangle.
int	getMaxX() Returns the highest X value from each created pixer.
int	getMaxY() Returns the highest Y value from each created pixer.
int	getMinX() Returns the lowest X value from each created pixer.
int	getMinY() Returns the lowest Y value from each created pixer.
int	getPixelCount() Returns the number of pixels over which each created pixer iterates.
BitSet	getPixels() Returns the pixel mask containing the data for this drawing.

Methods inherited from class java.lang.Object

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

Constructor Detail

PixelDrawing

public PixelDrawing(Rectangle bounds)

Constructs a drawing with bounds given by a rectangle.

Parameters:

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

PixelDrawing

public PixelDrawing(int x0,
                    int y0,
                    int width,
                    int height)

Constructs a drawing with bounds given explicitly.

Parameters:

x0 - lower bound of X coordinate

y0 - upper bound of Y coordinate

width - extent in X direction

height - extent in Y direction

Method Detail

addPixel

public void addPixel(int x,
                     int y)

Adds a single pixel to the list of pixels which have been plotted if it is within this drawing's bounds. 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

addPixelUnchecked

public void addPixelUnchecked(int x,
                              int y)

Adds a single pixel to the list of pixels which have been plotted without bounds checking. An assertion is made that the coordinates are outside of this drawing's bounds.

Parameters:

x - X coordinate, must be within this drawing's X bounds

y - Y coordinate, must be within this drawing's Y bounds

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

fillPolygon

public void fillPolygon(int[] xs,
                        int[] ys,
                        int np)

Draws a filled polygon on this drawing.

Parameters:

xs - X coordinates of vertices

ys - Y coordinates of vertices

np - number of vertices

fill

@Deprecated
public void fill(Shape shape)

Deprecated. may be slow for large shapes; use fillPolygon if possible

Fills an arbitrary shape.

Parameters:

shape - shape to fill

See Also:

Graphics2D.fill(java.awt.Shape)

contains

public boolean contains(int x,
                        int y)

Indicates whether a given position is within the bounds of this drawing.

Parameters:

x - X coordinate

y - Y coordinate

Returns:

true iff (x,y) is in bounds

getPixels

public BitSet getPixels()

Returns the pixel mask containing the data for this drawing. The coordinate mapping is not currently defined, but the return value of this method for two PixelDrawings with the same bounds will have the same bit-to-pixel correspondance; a set bit corresponds to a painted pixel. This value may be modified in place.

Returns:

bit map giving pixel data

getMinX

public int getMinX()

Description copied from interface: PixerFactory

Returns the lowest X value from each created pixer.

Specified by:

getMinX in interface PixerFactory

Returns:

minimum X coordinate

getMaxX

public int getMaxX()

Description copied from interface: PixerFactory

Returns the highest X value from each created pixer.

Specified by:

getMaxX in interface PixerFactory

Returns:

maximum X coordinate

getMinY

public int getMinY()

Description copied from interface: PixerFactory

Returns the lowest Y value from each created pixer.

Specified by:

getMinY in interface PixerFactory

Returns:

minimum Y coordinate

getMaxY

public int getMaxY()

Description copied from interface: PixerFactory

Returns the highest Y value from each created pixer.

Specified by:

getMaxY in interface PixerFactory

Returns:

maximum Y coordinate

getPixelCount

public int getPixelCount()

Description copied from interface: PixerFactory

Returns the number of pixels over which each created pixer iterates.

Specified by:

getPixelCount in interface PixerFactory

Returns:

pixel count

createPixer

public Pixer createPixer()

Returns a Pixer that interrogates this drawing's bitmap. May not be maximally efficient if it will be called many times.

Specified by:

createPixer in interface PixerFactory

Returns:

pixer