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Java Concepts Chapter 2 – Graphical Applications

Java Concepts Chapter 2 – Graphical Applications. Mr. Smith AP Computer Science A. Graphical Applications and Frame Windows. Objective Overview of drawing graphical applications You will be able to draw basic graphics in a frame window (more attractive than a console window)

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Java Concepts Chapter 2 – Graphical Applications

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  1. Java ConceptsChapter 2 – Graphical Applications Mr. Smith AP Computer Science A

  2. Graphical Applicationsand Frame Windows Objective • Overview of drawing graphical applications • You will be able to draw basic graphics in a frame window (more attractive than a console window) • Construct a frame of a certain size • Construct a component (such as a rectangles, circles, or a combination) • Add the component to the frame • Make the frame visible

  3. Graphical Applicationsand Frame Windows Constructing a Frame • Construct an object of the JFrame class JFrame frame = new JFrame(); • Set the size of the frame frame.setSize(300, 400); //Frame will be 300 pixels wide and 400 pixels tall //Omitting this step will make the frame 0x0 • Set the title of the frame (optional) frame.setTitle("Graphical Application"); • Set the "default close operation". frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //When the user closes the frame, the program will end • Make the frame visible frame.setVisible(true);

  4. Graphical Applicationsand Frame Windows Creating a Rectangle Component Object • In order to draw something in the frame, you must first create a component object and then add it to the frame • A component can consist of multiple graphics objects • Here are some of the classes that need to be imported in order to create a component object that draws a rectangle: import java.awt.Graphics; //primitive class – stores graphics state //including the current color, font, etc. import java.awt.Graphics2D; //Class used to draw shapes import java.awt.Rectangle; //Rectangles class import javax.swing.JComponent; //Used to draw in a frame

  5. Graphical Applicationsand Frame Windows Example of a Rectangle Component Object Class (used for creating, drawing, and positioning Rectangle objects) import java.awt.Graphics; //Allows you to manipulate the graphics //state (color, etc.) import java.awt.Graphics2D; //Contains methods to draw shapes import java.awt.Rectangle; import javax.swing.JComponent; public class RectangleComponent extends JComponent { //Place all the drawing instructions inside paintComponent method public void paintComponent(Graphics g) { Graphics2D g2 = (Graphics2D) g; //Cast to recover Graphics2D Rectangle box = new Rectangle(5, 10, 20, 30); //Construct rectangle g2.draw(box); //Draw rectangle box.translate(15, 25); //Move rectangle 15 units right and 25 down g2.draw(box); //Draw rectangle again } }

  6. Graphical Applicationsand Frame Windows Drawing a Rectangle Component • Construct a frame (see previous slide) • Construct an object of your component class RectangleComponent component = new RectangleComponent(); • Add the component to the frame frame.add(component); • Make the frame visible (see previous slide)

  7. Graphical Applicationsand Frame Windows Write a Client Program to View the Rectangles (used for instantiating the RectangleComponent object and adding it to the frame) import javax.swing.JFrame; public class RectangleViewer { public static void main(String [] args) { JFrame frame = new JFrame(); frame.setSize(300, 400); frame.setTitle("Graphics Application"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); RectangleComponent component = new RectangleComponent(); frame.add(component); frame.setVisible(true); } }

  8. Graphical Applicationsand Frame Windows Drawing a Face using Basic Shapes • You must first construct a "face" component and then add it to the frame • The face component will consist of different types of graphical objects for the head, eyes, and mouth • Here are some of the classes that need to be imported in order to use graphics: import java.awt.Color; //color class import java.awt.Graphics; //primitive graphics class import java.awt.Graphics2D;//Contains methods to draw shapes import java.awt.Rectangle; //Rectangles class Import java.awt.geom.Ellipse2D; Import java.awt.geom.Line2D; Import javax.swing.JPanel; import javax.swing.JComponent;

  9. Graphical Applicationsand Frame Windows Write a Face Component Class (used for creating, drawing, and positioning a face) import java.awt.Color; //color class import java.awt.Graphics; //primitive graphics class import java.awt.Graphics2D; //Extends Graphics class import java.awt.Rectangle; //Rectangles class import java.awt.geom.Ellipse2D; //Ellipse and circle class import java.awt.geom.Line2D; //Line class import javax.swing.JPanel; import javax.swing.JComponent; public class FaceComponentextendsJComponent { //Place drawing instructions inside this method public void paintComponent(Graphics g) { Graphics2D g2 = (Graphics2D) g; //Make graphics 2D Ellipse2D.Double head = new Ellipse2D.Double(5, 10, 100, 150); //Construct head (x, y, width, height) g2.draw(head); //Draw head Line2D.Double eye1 = new Line2D.Double(25, 70, 45, 90); //Construct left eye (x1, y1, x2, y2) g2.draw(eye1); Line2D.Double eye2 = new Line2D.Double(85, 70, 65, 90); //Construct right eye (x1, y1, x2, y2) g2.draw(eye2); Rectangle mouth = new Rectangle(30, 130, 50, 5); //Construct mouth (x, y, width, height) g2.setColor(Color.RED); //Color of mouth g2.fill(mouth); //Fill mouth with red g2.setColor(Color.BLUE); g2.drawString("Hello, Class!!!", 5, 175); //Draw greeting (“message”, x, y) } }

  10. Graphical Applicationsand Frame Windows Write a Client Program to View the Face (used for creating the FaceComponent object and adding it to the frame) import javax.swing.JFrame; public class FaceViewer { public static void main(String [] args) { JFrame frame = new JFrame(); //Instantiate new frame frame.setSize(300, 400); //Set frame size frame.setTitle("Alien Face"); //Set frame title frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); FaceComponent component = new FaceComponent(); //Instantiate component frame.add(component); //Add component to frame frame.setVisible(true); //Set frame visible } }

  11. Graphical Applicationsand Frame Windows Classwork/Homework Assignment • Download the following classes from my website: • FaceComponent – Face drawing object • FaceViewer – View the face • Use these classes as a starting point for your component class and client program to draw it in a frame • Refer to Java Concepts 2.11-2.13 for drawing other graphical objects (ellipse, lines, rectangles, etc.) • You can also refer to the link on my website named Drawing Geometric Shapes • Use your imagination and draw an object of your choice • Remember to include your name (JohnDoe) at the end of all classes you create, so I know who created them • Once these are finished, we will show them to the class

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