Read through the slides for your notes today.

Use the following slide as a reference for your graphics program

// Java0708.java // This program places the six methods from the // previous program into their own <House> class. import java.awt.*; import java.applet.*; public class Java0708 extends Applet { public void paint(Graphics g) House.drawFloors(g); House.drawRoof(g); House.drawDoor(g); House.drawWindows(g); House.drawChimney(g); } class House public static void drawFloors(Graphics g) Expo.setColor(g,Expo.blue); Expo.drawRectangle(g,200,200,500,300); Expo.drawRectangle(g,200,300,500,400); public static void drawRoof(Graphics g) Expo.setColor(g,Expo.red); Expo.drawLine(g,200,200,350,100); Expo.drawLine(g,500,200,350,100); Expo.drawLine(g,200,200,500,200); public static void drawDoor(Graphics g) Expo.setColor(g,Expo.black); Expo.drawRectangle(g,330,340,370,400); Expo.drawOval(g,350,370,10,20); Expo.fillCircle(g,366,370,3); public static void drawWindows(Graphics g) Expo.drawRectangle(g,220,220,280,280); Expo.drawLine(g,220,250,280,250); Expo.drawLine(g,250,220,250,280); Expo.drawRectangle(g,420,220,480,280); Expo.drawLine(g,420,250,480,250); Expo.drawLine(g,450,220,450,280); Expo.drawRectangle(g,320,220,380,280); Expo.drawLine(g,320,250,380,250); Expo.drawLine(g,350,220,350,280); Expo.drawRectangle(g,220,320,280,380); Expo.drawLine(g,220,350,280,350); Expo.drawLine(g,250,320,250,380); Expo.drawRectangle(g,420,320,480,380); Expo.drawLine(g,420,350,480,350); Expo.drawLine(g,450,320,450,380); public static void drawChimney(Graphics g) Expo.drawLine(g,420,146,420,80); Expo.drawLine(g,420,80,450,80); Expo.drawLine(g,450,80,450,166);

The next two slide are important for your understanding of using parameters

Important Rules About Using Parameters with Methods #1 The number of parameters in the method call must match the number of parameters in the method heading. The corresponding parameters in the method call must be the same type as the parameters in the heading. The sequence of the parameters in the method call must match the sequence of the parameters in the heading. The parameter identifiers in the method call may be the same identifier or a different identifier as the parameters in the heading.

Important Rules About Using Parameters with Methods #2 The number of actual parameters must match the number of formal parameters.   The corresponding actual parameters must be the same type as the formal parameters. The sequence of the actual parameters must match the sequence of the formal parameters. The actual parameter identifiers may be the same identifier as or a different identifier from as the formal parameters. These rules say the same thing as the previous slide.

The next two slides are important for you to understand the terminology. This will help you talk to each other intelligently and ask meaningful questions.

Variable Terminology Variables that are declared inside a method or block are called local variables. Local variables are only accessible inside the method or block that they are defined in. Variables that are declared inside a class, but outside any method, are class variables. Class variables are accessible by any method of the class. Class variables are also called attributes. If a variable is only used by one method, it should be declared inside that method as a local variable. If a variable is used by 2 or more methods of a class, it should be declared as a class variable.

Program Design Notes This was the first introduction to program design. Additional design features will be introduced as you learn more object-oriented programming. At this stage you can already consider the following: • Programs should use self-commenting identifiers. • Control structures and block structure need to use a consistent indentation style. • Specific tasks should be placed in modules called methods. • Similar methods accessing the same data should be placed in a class. • The main method should be used for program sequence, not large numbers of program statements.

This next section should give you a few ideas to help with your graphics program.

Section 7.6 Creating Methods with Other Methods

public class Java0725 extends Applet { public void paint(Graphics g) // Java0725.java // This program demonstrates a <picket> method that will be used to display a fence.   import java.awt.*; import java.applet.*; public class Java0725 extends Applet { public void paint(Graphics g) Expo.setBackground(g,Expo.black); Expo.setColor(g,Expo.tan); Expo.fillRectangle(g,0,500,1000,525); Expo.fillRectangle(g,0,600,1000,625); Expo.setColor(g,Expo.brown); for (int x = 2; x < 1000; x+=40) picket(g,x); } public static void picket(Graphics g, int x) Expo.fillPolygon(g,x,650,x,500,x+18,450,x+36,500,x+36,650); Expo.delay(250); // delay for ¼ a second

These pickets are actually drawn one at a time with a ¼ second delay NOTE: These pickets are actually drawn one at a time with a ¼ second delay between each picket. To see this effect execute the program on your computer.

The Logic of the picket Method picket(g,x); All graphics methods need g. x is the horizontal value of the bottom left corner of the picket. The y (vertical) value of the bottom left corner is always 650 since all pickets will be at the bottom of the screen. The other 4 coordinates of the picket are relative to the point (x,650). x+18,450 x,500 x+36,500 x,650 x+36,650

public class Java0726 extends Applet { public void paint(Graphics g) // Java0726.java // This program uses the <picket> method to create the <fence> method.   import java.awt.*; import java.applet.*; public class Java0726 extends Applet { public void paint(Graphics g) Expo.setBackground(g,Expo.black); fence(g); } public static void picket(Graphics g, int x) Expo.fillPolygon(g,x,650,x,500,x+18,450,x+36,500,x+36,650); Expo.delay(250); // delay for ¼ a second public static void fence(Graphics g) // cross beams Expo.setColor(g,Expo.tan); Expo.fillRectangle(g,0,500,1000,525); Expo.fillRectangle(g,0,600,1000,625); // pickets Expo.setColor(g,Expo.brown); for (int x = 2; x < 1000; x+=40) picket(g,x);

// Java0727.java // This program combines many user-defined methods to create a graphics image. import java.awt.*; import java.applet.*; public class Java0727 extends Applet { public void paint(Graphics g) Expo.setBackground(g,Expo.black); nightSky(g); fence(g); } public static void randomStar(Graphics g, int x) int y = Expo.random(25,175); int radius = Expo.random(15,20); int points = Expo.random(5,10); Expo.setRandomColor(g); Expo.fillStar(g,x,y,radius,points); Expo.delay(250); // delay for ¼ a second public static void nightSky(Graphics g) moon(g); for (int x = 25; x <= 825; x+= 50) randomStar(g,x); public static void moon(Graphics g) { Expo.setColor(g,Expo.white); Expo.fillCircle(g,920,85,70); Expo.setColor(g,Expo.black); Expo.fillCircle(g,895,70,60); } public static void picket(Graphics g, int x) Expo.fillPolygon(g,x,650,x,500,x+18,450, x+36,500,x+36,650); Expo.delay(250); // delay for ¼ a second public static void fence(Graphics g) // cross beams Expo.setColor(g,Expo.tan); Expo.fillRectangle(g,0,500,1000,525); Expo.fillRectangle(g,0,600,1000,625); // pickets Expo.setColor(g,Expo.brown); for (int x = 2; x < 1000; x+=40) picket(g,x);

public class Java0728 extends Applet { public void paint(Graphics g) // Java0728.java // This program does the exact same thing as the previous program, but without the structure methods. // Several method calls are commented out and in their place is the code from that method. // This is also done for some of the methods from the Expo class. // The intent is to show that using methods makes your program much more readable and easier to // work with. import java.awt.*; import java.applet.*; public class Java0728 extends Applet { public void paint(Graphics g) /////////////////////////////////////////////////////////////// // Expo.setBackground(g,Expo.black); Expo.setColor(g,Expo.black); Expo.fillRectangle(g,0,0,4800,3600); ////////////////////////////////////////////////////////////// // nightSky(g); ////////////////////////////////////////////////////////// // moon(g); Expo.setColor(g,Expo.white); Expo.fillCircle(g,920,85,70); Expo.fillCircle(g,895,70,60); // continued on the next several slides…

for (int centerX = 25; centerX <= 825; centerX += 50) { int centerY = Expo.random(25,175); int radius = Expo.random(15,20); int points = Expo.random(5,10); ////////////////////////////////////////////////////// // Expo.setRandomColor(g); int red = Expo.random(0,255); int green = Expo.random(0,255); int blue = Expo.random(0,255); Expo.setColor(g,red,green,blue); ///////////////////////////////////////////////////// // Expo.fillStar(g,x,y,radius,points); int halfRadius = radius / 2; switch(points) case 3 : halfRadius = 140 * radius / 500; break; case 4 : halfRadius = 170 * radius / 400; break; case 5 : halfRadius = 192 * radius / 500; break; case 6 : halfRadius = 233 * radius / 400; break; case 7 : halfRadius = 179 * radius / 500; break; case 8 : halfRadius = 215 * radius / 400; break; case 9 : halfRadius = 173 * radius / 500; break; case 10 : halfRadius = 212 * radius / 400; break; default : if (points < 52) if (points % 2 == 1) halfRadius = (180-points) * radius / 500; else halfRadius = (222-points) * radius / 400; } halfRadius = radius / 2;

int p = points; points *= 2; int xCoord[] = new int[points]; int yCoord[] = new int[points]; int currentRadius; for (int k = 0; k < points; k++) { if (k % 2 == 0) currentRadius = radius; else currentRadius = halfRadius; xCoord[k] = (int) Math.round(Math.cos(2 * Math.PI * k/points - Math.PI/2) * currentRadius) + centerX; yCoord[k] = (int) Math.round(Math.sin(2 * Math.PI * k/points - Math.PI/2) * currentRadius) + centerY; } int x = (p-5)/2+1; if (p >= 5 && p <= 51) switch(p % 4) case 1 : yCoord[x] = yCoord[x+1] = yCoord[points-x-1] = yCoord[points-x]; break; case 2 : yCoord[x] = yCoord[x+1] = yCoord[points-x-1] = yCoord[points-x]; yCoord[x+3] = yCoord[x+4] = yCoord[points-x-4] = yCoord[points-x-3]; break; case 3 : yCoord[x+2] = yCoord[x+3] = yCoord[points-x-3] = yCoord[points-x-2];

g.fillPolygon(xCoord,yCoord,points); /////////////////////////////////////////////////////// // Expo.delay(250); // delay for ¼ a second long startDelay = System.currentTimeMillis(); long endDelay = 0; while (endDelay - startDelay < 250) endDelay = System.currentTimeMillis(); } /////////////////////////////////////////////////////////////// // fence(g); // cross beams Expo.setColor(g,Expo.tan); Expo.fillRectangle(g,0,500,1000,525); Expo.fillRectangle(g,0,600,1000,625); // pickets Expo.setColor(g,Expo.brown); for (int x = 2; x < 1000; x+=40) { ////////////////////////////////////////////////////// // picket(g,x); ////////////////////////////////////////////////// //Expo.fillPolygon(g,x,650,x,500,x+18,450,x+36,500,x+36,650); Polygon poly = new Polygon(); poly.addPoint(x,650); poly.addPoint(x,500); poly.addPoint(x+18,450); poly.addPoint(x+36,500); poly.addPoint(x+36,650); g.fillPolygon(poly);

////////////////////////////////////////////////// // Expo.delay(250); // delay for ¼ a second long startDelay = System.currentTimeMillis(); long endDelay = 0; while (endDelay - startDelay < 250) endDelay = System.currentTimeMillis(); }

Next open Labs and follow the directions for the graphics lab Next open Labs and follow the directions for the graphics lab. If your graphic is too easy you will not receive credit. Due date will be Friday, Feb. 17.