©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Topics  Applets  Classes used for graphics Graphics Point Dimension Color Font FontMetrics Polygon

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Applets  A Java application is a stand-alone program with a main method (like the ones we've seen so far) that you run from the console.  A Java applet is a program that is intended to transported over the Web and executed using a web browser An applet also can be executed using the appletviewer tool of the Java Software Development Kit An applet doesn't have a main method Instead, there are several instance methods that serve specific purposes

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Applets  The paint method, for instance, is executed automatically and is used to draw the applet’s contents  The paint method accepts a parameter that is an object of the Graphics class

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Applets  The class that defines an applet extends the Applet class  An applet is embedded into an HTML file using a tag that references the bytecode file of the applet class  The bytecode version of the program is transported across the web and executed by a Java interpreter that is part of the browser

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The HTML applet Tag My Applet <applet code="Einstein.class" width=350 height=175>

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Graphics Classes  We introduce four standard classes related to drawing geometric shapes on a window: java.awt.Graphics java.awt.Color java.awt.Point java.awt.Dimension

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Graphics Class  Frames and Applets have a graphics context associated with them.  A Graphics object defines a graphics context on which we can draw shapes and text.  The Graphics class is in the java.awt package.  The state of a Graphics object includes such properties as height, width, foreground and background color and font.  Positions within the Graphics context are measured from the upper left corner and they have units of pixels.

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Graphics Class  Accessor methods are provided for getting height, width, color, font, …  Mutator methods are also provided for these properties.  The Graphics class has several methods for drawing shapes  There is also a method for displaying text.  We’ll see later that you can also display images.

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Graphics Methods

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Drawing a Line X Y g.drawLine (10, 20, 150, 45); g.drawLine (150, 45, 10, 20); or

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. drawRect  How the position of the rectangle is determined by the drawRect method. g.drawRect(50, 50, 100, 30);

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Drawing an Oval X Y g.drawOval (175, 20, 50, 80); bounding rectangle

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Drawing an Arc  An arc is a part of an oval  To draw you need to specify the bounding rectangle for the oval the starting angle (measured from the x-axis in degrees the angle the arc subtends

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Drawing an Arc g.drawArc (75, 20, 50, 80, 20, 90);

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Drawing a String  The drawString method can be used to display text in a Graphics context. void drawString( String text, int x, int y; *The position of the text relative to x and y is shown below

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Rectangles with a 3D Look  Another method in the Graphics class allows you to display rectangles that look 3D fill3DRect( int x, int y, int width, int height, boolean raised)  The boolean variable will be true if you want the rectangle to look raised and false to make it look lowered.

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Polygons  A polygon is a closed figure which is defined by a sequence of points called vertexes.  The awt package has a Polygon class  Create an empty Polygon with Polygon poly = new Polygon()  Add another vertex using poly.addPoint( x, y);  Use the Graphics drawPolygon and fillPolygon method to display the Polygon g.drawPolygon( poly); g.fillPolygon( poly)

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Color Class  The java.awt.Color class allows us to designate the color of an object.  The RGB scheme combines three values ranging from 0 to 255 for red, green, and blue. Color pinkColor; pinkColor = new Color(255,175,175)

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Color Class  There are public class constants defined in the Color class for common colors: Color.black Color.blue Color.green Color.magenta Color.orange

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Color Class  Every drawing surface has a background color g.setBackground(Color.white);  Every graphics context has a current foreground color The most recently set foreground color is what is used for drawing g.setColor(Color.blue); g.drawRect(50, 50, 100, 30);

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Using Fonts  Every Graphics object has a Font associated with it.  You can find out what the Font is with Font getFont( void);  You can change the Font with void setFont( Font);  The Font is part of the state of the graphics object a String will be drawn with the current Font.

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Font Class  A Font has three components Font name “Monospaced” “Serif” “SansSerif” Font Style (add BOLD and ITALIC to get both) Font.BOLD Font.ITALIC Font.PLAIN Font Size - integer number of points

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Creating a Font  Constructor takes three parameters Font( String fontFace, int fontStyle, int size)  Examples Font f1 = new Font( “SansSerif”, Font.BOLD, 24); Font f1 = new Font( “SansSerif”, Font.BOLD + Font.ITALIC, 16);

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Font Measurements  Sometimes, you want to know how big a String will be when you draw it  Create a FontMetrics object for your Graphics context FontMetrics fm = g.getFontMetrics( f1)  Use the stringWidth method int width = fm.getWidth( aString);

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Point class  A java.awt.Point object designates a point in two-dimensional space.  The Point class has public instance variables  To assign the position (10, 20) to a Point: Point pt = new Point(); pt.x = 10; pt.y = 20;

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Dimension Class  The java.awt.Dimension class can be used to create bounding rectangles that surround shapes. Dimension dim = new Dimension(); dim.width = 40; dim.height = 70;  Bounding rectangles