Topics AWT Classes Window Fundamentals Working with Frame Windows Creating a Frame Window in an Applet Creating a Windowed Program Displaying Information within a Window Working with Graphics Working with color Setting the Paint Mode Working with Fonts Managing Text Output Using Font Metrics.

AWT Classes one of Java’s largest packages

AWT  Abstract Window Toolkit The main purpose of the AWT is to support applet windows It can also be used to create stand-alone windows that run in a GUI environment, such as Windows. The AWT classes are contained in the java.awt package AWT Classes

AWT Classes - some of the original methods were deprecated and replaced by new ones when Java 1.1 was released. For backward- compatibility, Java 2 still supports all the original 1.0 methods.

AWT Classes

Window Fundamentals The AWT defines windows according to a class hierarchy that adds functionality and specificity with each level. The two most common windows are those derived from Panel, which is used by applets, those derived from Frame, which creates a standard window.

Window Fundamentals Much of the functionality of these windows is derived from their parent classes.

- Component An abstract class that encapsulates all of the attributes of a visual component.(All user interface elements are subclasses) It defines over a hundred public methods for managing events (such as mouse and keyboard input, positioning and sizing the window, and repainting.) Remembers the current foreground and background colors and the currently selected text font.

- Container A subclass of Component A container is responsible for laying out any components that it contains. Includes methods that allow other Component objects to be nested within it Other Container objects can be stored inside of a Container

- Panel A Panel is a window that does not contain a title bar, menu bar, or border. A concrete subclass of Container The superclass for Applet It doesn’t add any new methods; it simply implements Container.

- Panel Other components can be added to a Panel object by its add( ) method. add( ) method inherited from Container. you can position and resize the added components manually using the setLocation( ), setSize( ), or setBounds( ) methods defined by Component.

- Window This class creates a top-level window A top-level window is not contained within any other object; (it sits directly on the desktop) You will use a subclass of Window called Frame to create Window objects

- Frame A subclass of Window and has a title bar, menu bar, borders, and resizing corners. If you create a an applet window, it will contain a warning message, such as “Java Applet Window,” When a Frame window is created by a program rather than an applet, a normal window is created.

It creates a standard-style window You will use it to create child windows within applets, top-level or child windows for applications. Working with Frame Windows Two of Frame’s constructors: 1.Frame( )  creates a standard window that does not contain a title. 2.Frame(String title)  creates a window with the title specified by title

Several methods are used when working with Frame windows. Setting the Window’s Dimensions 1.void setSize(int newWidth, int newHeight) 2.void setSize(Dimension newSize) newWidth and newHeight  new size of the window newSize  the Dimension object contains width and height fields The dimensions are specified in terms of pixels. 3.Dimension getSize( )  used to obtain the current size of a window

Setting a Window’s Title void setTitle(String newTitle) newTitle  the new title for the window Closing a Frame Window setVisible(false). you must implement the windowClosing( ) method of the WindowListener interface Inside windowClosing( ), you must remove the window from the screen

Creating a Frame Window in an Applet STEPS: 1. Create a subclass of Frame. 2.Override any of the standard window methods ( init( ), start( ), stop( ), and paint( )) 3.Finally, implement the windowClosing( ) method of the WindowListener interface ( calling setVisible(false) when the window is closed ) you create an object of frame’s subclass. This causes a frame window to come into existence and you make window visible by calling setVisible( ).

Note the following : SampleFrame calls Frame’s constructor. (with super()). This causes a standard frame window to be created with the title passed in title. This example overrides the applet window’s start( ) and stop( ) methods. This causes the window to be removed automatically when you terminate the applet, when you close the window,

Sample output

Handling Events in a Frame Window Since Frame is a subclass of Component, it inherits all the capabilities defined by Component. So you can use and manage a frame window that you create just like you manage your applet’s main window. Whenever an event occurs in a window, the event handlers defined by that window will be called. Each window handles its own events.

Handling Events in a Frame Window The MouseListener Interface 1.void mouseClicked(MouseEvent me) 2.void mouseEntered(MouseEvent me) 3.void mouseExited(MouseEvent me) 4.void mousePressed(MouseEvent me) 5.void mouseReleased(MouseEvent me) The MouseMotionListener Interface 1.void mouseDragged(MouseEvent me) 2.void mouseMoved(MouseEvent me)

Handling Events in a Frame Window The WindowListener Interface 1.void windowActivated(WindowEvent we) 2.void windowClosed(WindowEvent we) 3.void windowClosing(WindowEvent we) 4.void windowDeactivated(WindowEvent we) 5.void windowDeiconified(WindowEvent we) 6.void windowIconified(WindowEvent we) 7.void windowOpened(WindowEvent we)

The following program creates a window that responds to mouse events. The main applet window also responds to mouse events.

Sample output

It is possible to create stand-alone AWT-based applications, too. To do this, simply create an instance of the window or windows you need inside main( ).

Sample output Once created, a frame window takes on a life of its own. Notice that main( ) ends with the call to appwin.setVisible(true).

Working with Graphics

All graphics are drawn relative to a window. ( main window of an applet, a child window of an applet, or a stand-alone application window.) The origin of each window is at the top-left corner and is 0,0. Coordinates are specified in pixels All output to a window takes place through a graphics context.

Working with Graphics A graphics context is encapsulated by the Graphics class and is obtained in two ways: It is passed to an applet when one of its various methods, such as paint( ) or update( ), is called. It is returned by the getGraphics( ) method of Component. The Graphics class defines a number of drawing functions.

Drawing Lines void drawLine (int startX, int startY, int endX, int endY) - displays a line in the current drawing color that begins at startX,startY and ends at endX,endY

Drawing Lines

Drawing Rectangles 1.void drawRect (int top, int left, int width, int height) 2. void fillRect (int top, int left, int width, int height) top,left  The upper-left corner of the rectangle width and height  The dimensions of the rectangle 3.void drawRoundRect (int top, int left, int width, int height, int xDiam, int yDiam)  draws rounded rectangle xDiam  The diameter of the rounding arc along the X axis yDiam  The diameter of the rounding arc along the Y axis.

Drawing Rectangles 4.void fillRoundRec t(int top, int left, int width, int height, int xDiam, int yDiam)  draws a filled rectangle

Drawing Rectangles Sample output

Drawing Ellipses and Circles 1.void drawOval (int top, int left, int width, int height) 2.void fillOval (int top, int left, int width, int height) The ellipse is drawn within a bounding rectangle whose upper-left corner is specified by top, left and whose width and height are specified by width and height To draw a circle, specify a square as the bounding rectangle

Drawing Ellipses and Circles

Sample output

Drawing Arcs 1.void drawArc (int top, int left, int width, int height, int startAngle, int sweepAngle) 2.void fillArc (int top, int left, int width, int height, int startAngle, int sweepAngle) top,left  upper-left corner of the bounding rectangle width and height  width and height of the bounding rectangle startAngle, sweepAngle  The arc is drawn from startAngle through the angular distance specified by sweepAngle

Drawing Arcs The arc is drawn counterclockwise if sweepAngle is positive, and clockwise if sweepAngl e is negative. Angles are specified in degrees. Zero degrees is on the horizontal, at the three o’clock position To draw an arc from twelve o’clock to six o’clock, the start angle would be 90 and the sweep angle 180.

Drawing Arcs

Sample output

Drawing Polygons 1.void drawPolygon (int x[ ], int y[ ], int numPoints) 2.void fillPolygon (int x[ ], int y[ ], int numPoints) The polygon’s endpoints are specified by the coordinate pairs contained within the x and y arrays numPoints  The number of points defined by x and y

Drawing Polygons

Sample output

Sizing Graphics To size a graphics object first obtain the current dimensions of the window by calling getSize( ) on the window object Once you have the current size of the window, you can scale your graphical output accordingly. getSize( ) returns the dimensions of the window encapsulated within a Dimension object

Sizing Graphics

Working with Color

Java supports color in a portable, device-independent fashion Color is encapsulated by the Color class and defines constants for common colors 1. Color (int red, int green, int blue) 2. Color (int rgbValue) 3. Color (float red, float green, float blue) You can also create your own colors, using one of the color constructors.

Working with Color 1. The first constructor takes three integers that specify the color as a mix of red, green, and blue. These values must be between 0 and The second color constructor takes a single integer that contains the mix of red, green, and blue packed into an integer red in bits 16 to 23, green in bits 8 to 15, and blue in bits 0 to 7 3.The final constructor, takes three float values (between 0.0 and 1.0) that specify the relative mix of red, green, and blue

Using Hue, Saturation, and Brightness (HSB) An alternative color model to red-green-blue (RGB) hue  specified with a number between 0.0 and 1.0 Saturation  ranges from 0.0 to 1.0, representing light pastels to intense hues Brightness values also range from 0.0 to 1.0, where 1 is bright white and 0 is black

Color Methods The Color class defines several methods that help manipulate colors. 1.static int HSBtoRGB(float hue, float saturation, float brightness) 2.static float[ ] RGBtoHSB(int red, int green, int blue, float values[ ]) 3.int getRed( )  Red components of RBG 4.int getGreen( )  Green components of RBG 5.int getBlue( )  Blue components of RBG 6.int getRGB( )  packed RGB representation of a color

Setting the Current Graphics Color You can change this color by calling the Graphics method setColor( ): void setColor (Color newColor) newColor  specifies the new drawing color You can obtain the current color by calling getColor( ), Color getColor( )

A Color Demonstration Applet

Setting the XOR Mode By default, new output to a window overwrites any preexisting contents. However, it is possible to have new objects XORed onto the window by using setXORMode( ) void setXORMode(Color xorColor) xorColor  specifies the color that will be XORed to the window when an object is drawn.

Setting the Paint Mode To return to overwrite mode, call setPaintMode( ), shown here: void setPaintMode ( ) The advantage of XOR mode is that the new object is always guaranteed to be visible no matter what color the object is drawn over

the following program displays cross hairs that track the mouse pointer. The cross hairs are XORed onto the window and are always visible, no matter what the underlying color is.

Sample output

Working with Fonts The AWT provides flexible font-manipulation Allows dynamic selection of fonts. Fonts have 1.A family name  the general name of the font, such as Courier 2.A logical font name  specifies a category of font such as Monospaced 3. A face name  a specific font, such as Courier Italic.

Working with Fonts Fonts are encapsulated by the Font class

Working with Fonts Some Methods Defined by Font

Working with Fonts Some Methods Defined by Font

Determining the Available Fonts 1. To obtain font information, you can use the getAvailableFontFamilyNames( ) method defined by the GraphicsEnvironmen t class String[ ] getAvailableFontFamilyNames( ); This method returns an array of strings that contains the names of the available font families.

Determining the Available Fonts 2. In addition, the getAllFonts( ) method is defined by the GraphicsEnvironment class Font[ ] getAllFonts( ) This method returns an array of Font objects for all of the available fonts. Since these methods are members of GraphicsEnvironment, you need a GraphicsEnvironment reference to call them. You can obtain this reference by using static GraphicsEnvironment getLocalGraphicsEnvironment( )

Determining the Available Fonts

Sample output

Creating and Selecting a Font To select a new font, you must first construct a Font object that describes that font. One Font constructor has this general form: Font (String fontName, int fontStyle, int pointSize) fontName  specifies the name of the desired font. fontStyle  The style of the font. pointSize  The size, in points, of the font

Creating and Selecting a Font fontName All Java environments will support the following fonts: Dialog, DialogInput, SansSerif, Serif, Monospaced, and Symbol. fontStyle one or more of these three constants: Font.PLAIN Font.BOLD Font.ITALIC. To combine styles, OR them together. For example, Font.BOLD | Font.ITALIC

Creating and Selecting a Font To use a font that you have created, you must select it using setFont( ), which is defined by Component void setFont (Font fontObj) fontObj  the object that contains the desired font

Creating and Selecting a Font The following program outputs a sample of each standard font. Each time you click the mouse within its window, a new font is selected and its name is displayed

Creating and Selecting a Font

Obtaining Font Information To obtain information about the currently selected font, you must first get the current font by calling getFont( ). This method is defined by the Graphics class Font getFont( ) Once you have obtained the currently selected font, you can retrieve information about it using various methods defined by Font.

Obtaining Font Information this applet displays the name, family, size, and style of the currently selected font:

Obtaining Font Information

Managing Text Output Using FontMetrics

FontMetrics class Encapsulates various information about a font. Basic Terms : When drawString( ) method is used, the location specifies left edge of the baseline of the characters, not at the upper-left corner as is usual with other drawing methods

FontMetrics class FontMetrics defines several methods that help you manage text output.

FontMetrics class FontMetrics defines several methods that help you manage text output.

FontMetrics class FontMetrics defines several methods that help you manage text output.

Displaying Multiple Lines of Text Using FontMetrics

Centering Text

AWT Class Hierarchy