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Any object can be drawn …

Any object can be drawn …. Suppose we are creating a Dog class ………….. public class Dog { private String name = “Fido”; //dog’s name private String breed = “unknown”; // dog’s breed public Dog (String nm, String brd){ name = nm;

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Any object can be drawn …

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  1. Any object can be drawn … Suppose we are creating a Dog class ………….. public class Dog { private String name = “Fido”; //dog’s name private String breed = “unknown”; // dog’s breed public Dog (String nm, String brd){ name = nm; breed = brd; } // .... We might have some other methods here public String toString( ) { return “ " + name; } }

  2. And we wanted the capability of ‘drawing’ a dog…….. Remember, we have been using a Graphics2D object to draw shapes, If one of our Dog methods had access to a Graphics2D object, then it could ‘draw a dog’ ! SO.. we will add the following method to the Dog class.. public void draw(Graphics2D g2){ x = 10; y = 10; Ellipse2D.Double oval = new Ellipse2D.Double(x,y,100,50); g2.draw(oval); //eyes oval = new Ellipse2D.Double(x+25,y+12,5,5); g2.draw(oval); oval = new Ellipse2D.Double(x+12,y+12,5,5); g2.draw(oval); //nose oval = new Ellipse2D.Double(x+16,y+25,10,10); g2.fill(oval); // left ear oval = new Ellipse2D.Double(x+62,y+13,50,75); g2.fill(oval); }

  3. Any object can be drawn … We may want to allow our Dog to be constructed with an initial drawing position … public class Dog { String name = “Fido”; String breed = “unknown”; ..position is now also specified as instance data private int x = 10; //x,y drawing position, default 10,10 private int y = 10; public Dog (String nm, String brd, int xpos, int ypos){ name = nm; breed = brd; x = xpos; y = ypos; }

  4. Any object can be drawn … Now any JComponent can easily add a Dog drawing … import javax.swing.JComponent; import java.awt.Graphics2D; import java.awt.Graphics; import java.awt.Color; public class DrawPad extends JComponent { public void paintComponent(Graphics g) { Graphics2D g2 = (Graphics2D) g; // create two dog objects Dog d1 = new Dog("George","Poodle", 10,10); Dog d2 = new Dog( "Fred","mutt", 150,150); // call Dog object’s Draw method d1.draw(g2); d2.draw(g2); } }

  5. Drawing Complex Shapes • Good practice: Make a class for each graphical shape • Plan complex shapes by making sketches on graph paper class Car{ . . . public void draw(Graphics2D g2) { // Drawing instructions . . . }}

  6. File CarComponent.java import java.awt.Graphics; import java.awt.Graphics2D; import javax.swing.JComponent;: // This component draws two car shapes. public class CarComponent extends JComponent { public void paintComponent(Graphics g) { Graphics2D g2 = (Graphics2D) g; Car car1 = new Car(0, 0); //car created at position 0,0 int x = getWidth() - Car.WIDTH; //another at lower right int y = getHeight() - Car.HEIGHT; Car car2 = new Car(x, y); //create car car1.draw(g2); //draw both cars car2.draw(g2); } }

  7. Drawing Cars • Draw two cars: one in top-left corner of window, and another in the bottom right • Compute bottom right position, inside paintComponent method: • getWidth and getHeight are applied to object that executes paintComponent (the JComponent object) • If window is resized paintComponent is called and car position recomputed int x = getWidth() - 60;int y = getHeight() - 30;Car car2 = new Car(x, y); Continued…

  8. File CarViewer.java import javax.swing.JFrame; public class CarViewer{ public static void main(String[] args) { JFrame frame = new JFrame(); finalint FRAME_WIDTH = 300; //set up frame finalint FRAME_HEIGHT = 400; frame.setSize(FRAME_WIDTH, FRAME_HEIGHT); frame.setTitle("Two cars"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //create component and add to frame CarComponent component = new CarComponent(); frame.add(component); frame.setVisible(true); //make frame visible } }

  9. Drawing Cars The Car Component Draws 2 Shapes

  10. Plan Complex Shapes on Graph Paper Using Graph Paper to Find Shape Coordinates

  11. draw method details.. public void draw(Graphics2D g2) { Rectangle2D.Double body = new Rectangle2D.Double(xLeft, yTop + 10, 60, 10); Ellipse2D.Double frontTire = new Ellipse2D.Double(xLeft + 10, yTop + 20, 10, 10); Ellipse2D.Double rearTire= new Ellipse2D.Double(xLeft + 40, yTop + 20, 10, 10); // top of front windshield Point2D.Double r1 = new Point2D.Double(xLeft + 10, yTop + 10); Point2D.Double r2 = new Point2D.Double(xLeft + 20, yTop); // front of roof Point2D.Double r3 = new Point2D.Double(xLeft + 40, yTop); // rear of roof // bottom of rear windshield Point2D.Double r4 = new Point2D.Double(xLeft + 50, yTop + 10); Line2D.Double frontWindshield = new Line2D.Double(r1, r2); Line2D.Double roofTop = new Line2D.Double(r2, r3); Line2D.Double rearWindshield = new Line2D.Double(r3, r4); g2.draw(body); g2.draw(frontTire); g2.draw(rearTire); g2.draw(frontWindshield); g2.draw(roofTop); g2.draw(rearWindshield);

  12. Reading Text Input • A graphical application can obtain input by displaying a JOptionPane • The showInputDialog method displays a prompt and waits for user input • The showInputDialog method returns the string that the user typed String input = JOptionPane.showInputDialog("Enter x");double x = Double.parseDouble(input); Continued…

  13. Reading Text Input An Input Dialog Box

  14. ColoredSquareComponent.java import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Rectangle; import javax.swing.JComponent; // A component that shows a colored square. public class ColoredSquareComponent extends JComponent{ private Color fillColor; public ColoredSquareComponent(Color aColor) { // param aColor the fill color for the square fillColor = aColor; } public void paintComponent(Graphics g) { Graphics2D g2 = (Graphics2D) g; g2.setColor(fillColor); // now draw a filled square

  15. ColoredSquareComponent.java // now draw a filled square final int SQUARE_LENGTH = 100; Rectangle square = new Rectangle( (getWidth() - SQUARE_LENGTH) / 2, (getHeight() - SQUARE_LENGTH) / 2, SQUARE_LENGTH, SQUARE_LENGTH); g2.fill(square); } }

  16. ColorViewer.java- allows user to specify color import java.awt.Color; import javax.swing.JFrame; import javax.swing.JOptionPane; public class ColorViewer{ public static void main(String[] args) { JFrame frame = new JFrame(); final int FRAME_WIDTH = 300; final int FRAME_HEIGHT = 400; frame.setSize(FRAME_WIDTH, FRAME_HEIGHT); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); Continued…

  17. ColorViewer.java- allows user to specify color //ask user for color, create and draw component String input; input = JOptionPane.showInputDialog("red:"); double red = Double.parseDouble(input); input = JOptionPane.showInputDialog("green:"); double green = Double.parseDouble(input); input = JOptionPane.showInputDialog("blue:"); double blue = Double.parseDouble(input); //create color object using user RBG values) Color fillColor = new Color( (float) red, (float) green, (float) blue); ColoredSquareComponent component = new ColoredSquareComponent(fillColor); frame.add(component); frame.setVisible(true); } }

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