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TopicsAWT Classes

Window FundamentalsWorking with Frame Windows

Creating a Frame Window in an Applet

Creating a Windowed ProgramDisplaying Information within a Window

Working with Graphics

Working with color

Setting the Paint Mode

Working with Fonts

Managing Text Output Using Font Metrics.

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AWT Classesone of Javas largest packages

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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 thejava.awtpackage

AWT Classes

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AWT Classes - some of the original methods were deprecatedand replaced by new ones when Java 1.1 was released. For backward-

compatibility, Java 2 still supports all the original 1.0 methods.

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AWT Classes

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AWT Classes

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AWT Classes

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AWT Classes

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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.

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Window Fundamentals

Much of the functionality of these windows is derived from their

parent classes.

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-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.

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- Container

A subclass ofComponent

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

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-Panel

A Panelis a window that does not contain a title

bar, menu bar, or border.

A concrete subclass ofContainer

The superclass for Applet

It doesnt add any new methods; it simply

implements Container.

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-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 setLocation( ),

setSize( ), or setBounds( ) methods defined

by Component.

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- 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

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-Frame

A subclass of Window and has a title bar, menu bar,

borders, and resizing corners.

If you create a Frame object from with in an applet

window , it will contain a warning message, such as

Java Applet Window, to the user that an applet

window has been created.

When a Frame window is created by a program

rather than an applet, a normal window is created.

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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 ofFrames 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

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Several methods are used when working with Frame

windows.

Setting the Windows Dimensions

1. void setSize(int newWidth, int newHeight)

2. void setSize(Dimension newSize)

newWidth and newHeight new size of the window

newSizethe Dimension object contains width and height

fieldsThe dimensions are specified in terms of pixels.

3. Dimension getSize( )used to obtain the current size of awindow

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Setting a Windows 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

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Creating a Frame Window in an Applet

STEPS:1. Create a subclass of Frame.

2. Override any of the standard applet methods

(init( ), start( ), stop( ), and paint( )) to show or hide frame as needed

3. Finally, implement the windowClosing( ) method of

the WindowListener interface calling

setVisible(false) when the window is closed

you create an object of frames subclass. This causes a frame

window to come into existence and you make window visible by

calling setVisible( ).

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Note the following :

SampleFrame calls Frames constructor. (with super()).

This causes a standard frame window to be created with

the title passed in title.

This example overrides the applet windows start( ) and

stop( ) methods. This causes the window to be removed

automatically when you terminate the applet, when you

close the window,

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Sample output

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Handling Events in a Frame Window

Since Frame is a subclass ofComponent, 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 applets 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.

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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 Interface1. void mouseDragged(MouseEvent me)

2. void mouseMoved(MouseEvent me)

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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)

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The following program creates a window that responds to mouse

events. The main applet window also responds to mouse events.

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Sample output

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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( ).

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Sample output

Once created, a frame window takes on a life of its own. Notice

that main( ) endswith the call to appwin.setVisible(true).

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Working withGraphics


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All graphics are drawn relative to a window.

(main window of an applet, a child window of an applet, or a stand-aloneapplication 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.


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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

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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 andends at endX,endY

Drawing Lines

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Drawing Lines

Drawing Rectangles

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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 axisyDiam The diameter ofthe rounding arc along the Y axis.

Drawing Rectangles

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Drawing Rectangles

4. voidfillRoundRect(int top, int left, int width, int height, int

xDiam, int yDiam) draws a filled rectangle

Drawing Rectangles

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Drawing Rectangles

Sample output

Sample output

Drawing Ellipses and Circles

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1. void drawOval(int top, int left, int width, int height)

2. voidfillOval(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


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Sample output

Drawing Arcs

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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,leftupper-left corner of the bounding rectangle

width and height width and heightof the bounding rectangle

startAngle , sweepAngleThe arc is drawn from startAngle through

the angular distance specified by sweepAngle

Drawing Arcs

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Drawing Arcs

The arc is drawn counterclockwise if sweepAngle is positive,

and clockwise ifsweepAngle is negative.

Angles are specified in degrees.

Zero degrees is on the horizontal, at the three oclock position

To draw an arc from twelve oclock to six oclock, the start angle

would be 90 and the sweep angle 180.

Drawing Arcs

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Drawing Arcs

Drawing Arcs

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Drawing Arcs

Sample output

Drawing Polygons

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Drawing Polygons

1. void drawPolygon(int x[ ], int y[ ], int numPoints)

2. voidfillPolygon(int x[ ], int y[ ], int numPoints)

The polygons endpoints are specified by the coordinate pairs

contained within thex and y arrays

numPointsThe number of points defined byx and y

Drawing Polygons

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Drawing Polygons

Drawing Polygons

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Drawing Polygons

Sample output

Sizing Graphics

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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

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Sizing Graphics

Sizing Graphics

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Sizing Graphics

Sizing Graphics

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Sizing Graphics

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Working withColor

Working with Color

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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

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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 255

2. 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)

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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, representinglight pastels to intense hues

Brightness values also range from 0.0 to 1.0, where 1is bright white and 0 is black

Color Methods

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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

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Setting the Current Graphics Color

You can change this color by calling the Graphics method setColor( ):

void setColor(Color newColor)

newColorspecifies the new drawing color

You can obtain the current color by calling getColor( ),

Color getColor( )

A Color Demonstration Applet

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A Color Demonstration

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Applet

Setting the XOR Mode

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g

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)

xorColorspecifies the color that will be XORed to the window

when an object is drawn.

Setting the Paint Mode

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g

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

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pointer. The cross hairs are XORed onto the window and are always

visible, no matter what the underlying color is.

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Sample output

Working with Fonts

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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

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Working with Fonts

Fonts are encapsulated by the Font class

Working with Fonts

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Working with Fonts

Some Methods Defined by Font

Working with Fonts

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Working with Fonts

Some Methods Defined by Font

Determining the Available Fonts

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1. To obtain font information, you can use the

getAvailableFontFamilyNames( ) method defined by the

GraphicsEnvironment class

String[ ]getAvailableFontFamilyNames();

This method returns an array of strings that contains the names

of the available font families.


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g

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( )


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Sample output

Creating and Selecting a Font

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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


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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


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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


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The following program outputs a sample of each standard font.

Each time you click the mouse within its window, a new font isselected and its name is displayed


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Obtaining Font Information

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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

FontgetFont( )

Once you have obtained the currently selected font, you can

retrieve information about it using various methods defined by

Font.

this applet displays the name, family, size, and style of the

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currently selected font:

Obtaining Font Information

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Managing Text Output

Using FontMetrics

FontMetrics class

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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

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FontMetrics defines several methods that help you manage text

output.

FontMetrics class

d f l h d h h l

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output.

FontMetrics class

i d fi l h d h h l

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output.

Displaying Multiple Lines of Text Using FontMetrics

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Centering Text

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Centering Text

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Centering Text

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Centering Text

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