Java Java Programming, Programming,

Second EditionSecond Edition

Chapter TenChapter TenGraphicsGraphics

In this chapter, you In this chapter, you will:will:

• Learn about the paint() and repaint() Learn about the paint() and repaint() methodsmethods

• Use the drawString() method to draw Use the drawString() method to draw stringsstrings

• Use the setFont() and setColor() Use the setFont() and setColor() Graphic object methodsGraphic object methods

• Create Graphics and Graphics 2D Create Graphics and Graphics 2D objectsobjects

• Draw lines, rectangles, ovals, arcs, Draw lines, rectangles, ovals, arcs, and polygonsand polygons

• Copy an area• Learn more about fonts and their

methods• Draw with Java 2D graphics• Add sound, images, and simple

animations to Swing applets

Learning about the paint() and Learning about the paint() and repaint() Methods repaint() Methods

• paint() method- Runs when Java displays your Swing applet– Is used within every Swing applet– public void paint (Graphics g)

• repaint() method- Use when a window needs to be updated, such as when it contains new images– Java system calls the repaint() method when it

needs to update a window– repaint() creates a Graphics object for you

Using the drawString() Method Using the drawString() Method to Draw Methodsto Draw Methods

• drawString() method- Allows you to draw a String in a Swing applet window

• Requires three arguments:– A String– An x-axis coordinate– A y-axis coordinate

Using the setFont() and setColor() Using the setFont() and setColor() Graphics Object MethodsGraphics Object Methods

• setFont() and setColor() Graphics object methods- Improve the appearance of Graphics objects– setFont() method requires a Font object– Font someFont = new

Font(“TimesRoman”,Font.BOLD, 16);

Using the setFont() and setColor() Using the setFont() and setColor() Graphics Object MethodsGraphics Object Methods

• setColor() method- Color class contains 13 constants– Use any of these constants as an

argument to the setColor() method– brush.setColor(Color.green);

The Swing Applets Background The Swing Applets Background ColorColor

setBackground()• setBackground(Color.pink);• Change the background color of your

Swing applet• You do not need a Graphics object to

change the Swing applet’s background color

Creating Graphics and Creating Graphics and Graphics 2D ObjectsGraphics 2D Objects

• You can instantiate your own Graphics or Graphics 2D objects

Drawing LinesDrawing Lines• drawLine() method- To draw a straight

line between any two points on the screen

• Takes four arguments– The x- and y-coordinates of the line’s

starting point– The x- and y-coordinates of the line’s

ending point• pen.drawLine(10,10,100,200);

Drawing RectanglesDrawing Rectangles• drawRect() and fillRect() methods- To draw

the outline of a rectangle or to draw a solid, or filled, rectangle

• These methods require four arguments:– First two represent the x- and y-coordinates of

the upper-left corner of the rectangle– Last two represent the width and height of the

rectangle– drawRect(20,100,200,10);

Drawing RectanglesDrawing Rectangles• clearRect() method- Draws a rectangle• Requires four arguments• drawRect() and fillRect() methods use

the current drawing color• clearRect() method uses the current

background color to draw what appears to be an empty or “clear” rectangle

Drawing RectanglesDrawing Rectangles• drawRoundRect() method- Create

rectangles with rounded corners• Requires six arguments:

– x- and y-coordinates of the upper-left corner

– The width and height– The arc width and height associated

with the rounded corners

Drawing OvalsDrawing Ovals• drawOval()• fillOval()• Both draw ovals using the same four

arguments that rectangles use

Drawing ArcsDrawing Arcs• Draw an arc using the Graphics drawArc()

method• Provide six arguments:

– x-coordinate of the upper-left corner of an imaginary rectangle that represents the bounds of the imaginary circle that contains the arc

– y-coordinate of the same point– Width of the imaginary rectangle that represents the

bounds of the imaginary circle that contains the arc– Height of the same imaginary rectangle– Beginning arc position– Arc angle

Drawing ArcsDrawing Arcs• fillArc() method- Creates a solid arc• Arc is drawn and two straight lines are

drawn from the arc end points to the center of the imaginary circle whose perimeter the arc occupies

• solidarc.fillArc(10,50,100,100,20,320);• solidarc.fillArc(200,50,100,100,340,40);

Creating Three-Dimensional Creating Three-Dimensional RectanglesRectangles

• draw3DRect() method- To draw a rectangle that appears to have “shadowing” on two of its edges

• Requires a fifth argument in addition to the x- and y-coordinates and width and height

• Fifth argument is a Boolean value– True if you want the raised rectangle effect– False if you want the lowered rectangle effect

• fill3DRect() method for creating filled three-dimensional rectangles

Creating PolygonsCreating Polygons• drawPolygon() method- To create a shape

that is more complex than a rectangle• Requires three arguments: two integer

arrays and a single integer– First integer array holds a series of x-

coordinate positions– Second array holds a series of corresponding y-

coordinate positions– Third integer argument is the number of pairs

of points you want to connect

Copying an AreaCopying an Area• copyArea() method- Use to copy an

area• Requires 6 parameters

– x-coordinate and y-coordinate of the upper-left corner of the area to be copied

– Width and height of the area to be copied– The horizontal and vertical displacement of

the destination of the copy

Learning More about Fonts and Learning More about Fonts and Their MethodsTheir Methods

• getAllFonts()- Used to discover the fonts that are available on your system– Part of the GraphicsEnvironment class in

the java.awt package• getScreenResolution() and

getScreenSize()-Used to get the resolution and screen size of your system– getScreenResolution()- returns the

number of pixels as an int type

Drawing with Java 2D Drawing with Java 2D GraphicsGraphics

• Java 2D creates higher-quality two-dimensional graphics, images, and text– Includes fill patterns such as gradients– Strokes that define the width and style

of a drawing stroke– Anti-aliasing, a graphics technique for

producing smoother on-screen graphics

Specifying the Rendering Specifying the Rendering AttributesAttributes

• Fill patterns- Control how a drawing will be filled in

• Gradient fill- A gradual shift of color– Acyclic- color shift occurs once– Cyclic- color shift occurs repeatedly

• setStroke()- Changes the width of the drawing line

Adding Sound, Images, and Adding Sound, Images, and Simple Animation to Swing Simple Animation to Swing

AppletsApplets• Java 2 supports sound• Use the play() method to retrieve

and play sound– play() with one argument- the argument

is a URL– play() with two arguments- loads and

plays the audio file

Adding Sound, Images, and Adding Sound, Images, and Simple Animation to Swing Simple Animation to Swing

AppletsApplets• Images formats supported by Java

include:– Graphics Interchange Format (GIF)

• Maximum of 256 colors– Join Photographic Experts Group (JPEG)

• Stores mostly photographs– Portable Network Graphics (PNG)

• Stores images in a lossless form