Recipe 13.12 Program: PlotterAWT

In Recipe 9.12, we discussed a series of Plotter classes. The PlotterAWT class shown in Example 13-7 extends that to provide a "plot preview" service: before being plotted on a (probably slow) plotter, the plot is displayed in an AWT window using the Graphics drawing primitives.

Example 13-7. PlotterAWT.java

import java.awt.*; import java.awt.event.*; import com.darwinsys.swingui.WindowCloser; /**  * A Plotter subclass for drawing into an AWT Window. Reflecting back  * to AWT gives us a "known working" plotter to test on.  * You can also steal this as a basis for your own plotter driver.  * @author    Ian Darwin  */ public class PlotterAWT extends Plotter {     Frame f;     PCanvas p;     Graphics g;     Font font;     FontMetrics fontMetrics;     PlotterAWT( ) {         super( );         f = new Frame("Plotter");         p = new PCanvas(MAXX, MAXY);         f.add(p);         f.pack( );         f.setVisible(true);         f.addWindowListener(new WindowCloser(f, true));  // ignore deprecation warning         g = p.getOsGraphics( );     }     public void drawBox(int w, int h) {         g.drawRect(curx, cury, w, h);         p.repaint( );     }     public void rmoveTo(int incrx, int incry){         moveTo(curx += incrx, cury += incry);     }     public void moveTo(int absx, int absy){         if (!penIsUp)             g.drawLine(curx, cury, absx, absy);         curx = absx;         cury = absy;     }     public void setdir(float deg){}     void penUp( ){ penIsUp = true; }     void penDown( ){ penIsUp = false; }     void penColor(int c){         switch(c) {         case 0: g.setColor(Color.white); break;         case 1: g.setColor(Color.black); break;         case 2: g.setColor(Color.red); break;         case 3: g.setColor(Color.green); break;         case 4: g.setColor(Color.blue); break;         default: g.setColor(new Color(c)); break;         }     }     void setFont(String fName, int fSize) {         font = new Font(fName, Font.BOLD, fSize);         fontMetrics = p.getFontMetrics(font);     }     void drawString(String s) {         g.drawString(s, curx, cury);         curx += fontMetrics.stringWidth(s);     }     /** A Member Class that contains an off-screen Image that is      * drawn into; this component's paint( ) copies from there to      * the screen. This avoids having to keep a list of all the      * things that have been drawn.      */     class PCanvas extends Canvas {         Image offScreenImage;         int width;         int height;         Graphics pg;         PCanvas(int w, int h) {             width = w;             height = h;             setBackground(Color.white);             setForeground(Color.red);         }         public Graphics getOsGraphics( ) {             return pg;         }         /** This is called by AWT after the native window peer is created,          * and before paint( ) is called for the first time, so          * is a good time to create images and the like.          */         public void addNotify( ) {             super.addNotify( );             offScreenImage = createImage(width, height);             // assert (offScreenImage != null);             pg = offScreenImage.getGraphics( );         }         public void paint(Graphics pg) {             pg.drawImage(offScreenImage, 0, 0, null);         }         public Dimension getPreferredSize( ) {             return new Dimension(width, height);         }     } }