Object-Oriented Techniques - Java - page 326

I'll present a high-level class that abstracts the key characteristics of a series of such plotters
made by different vendors. It would be used, for example, in an analytical or data-explora-
tion program to draw colorful charts showing the relationships found in data. But I don't
want my main program to worry about the gory details of any particular brand of plotter, so
I'll abstract into a Plotter class, whose source is as follows:

plotter/Plotter.java

/**
* Plotter abstract class. Must be subclassed
* for X, DOS, Penman, HP plotter, etc.
*
* Coordinate space: X = 0 at left, increases to right.
* Y = 0 at top, increases downward (same as AWT).
*
* @author Ian F. Darwin
*/
public public abstract abstract class class Plotter Plotter {

public public final final int int MAXX = 800 ;

public public final int MAXY = 600 ;

/** Current X co-ordinate (same reference frame as AWT!) */
protected

final int

protected int int curx ;

/** Current Y co-ordinate (same reference frame as AWT!) */
protected

protected int int cury ;

/** The current state: up or down */
protected protected boolean boolean penIsUp ;

/** The current color */
protected protected int int penColor ;

Plotter () {
penIsUp = true true ;

curx = 0 ; cury = 0 ;

}
abstract abstract void void rmoveTo ( int int incrx , int int incry );

abstract abstract void void moveTo ( int int absx , int int absy );

abstract abstract void void penUp ();

abstract abstract void void penDown ();

abstract abstract void void penColor ( int int c );

abstract abstract void void setFont ( String fName , int int fSize );

abstract abstract void void drawString ( String s );

/* Concrete methods */