Java Graphics Programming

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   Graphics is one of the most important features of Java. Java applets can be written to draw lines, arcs, figures, images and text in different fonts and styles. Different colors can also be incorporated in display.

Contents

• The Graphics Class


• Lines and Rectangles


• Circles and Ellipses


• Drawing Arcs


• Drawing Polygons

The Graphics Class

The graphics class defines a number of drawing functions, Each shape can be drawn edge-only or filled. To draw shapes on the screen, we may call one of the methods available in the graphics class. The most commonly used drawing methods included in the graphics class are listed below. To draw a shape, we only need to use the appropriate method with the required arguments.

Drawing Methods of the Graphics Class

Sr.No	Method	Description
1.	clearRect()	Erase a rectangular area of the canvas.
2.	copyAre()	Copies a rectangular area of the canvas to another area
3.	drawArc()	Draws a hollow arc
4.	drawLine()	Draws a straight line
5	drawOval()	Draws a hollow oval
6	drawPolygon()	Draws a hollow polygon
7	drawRect()	Draws a hollow rectangle
8.	drawRoundRect()	Draws a hollow rectangle with rounded corners
9.	drawString()	Display a text string
10.	FillArc()	Draws a filled arc
11.	fillOval()	Draws a filled Oval
12.	fillPolygon()	Draws a filled Polygon
13.	fillRect()	Draws a filled rectangle
14.	fillRoundRect()	Draws a filled rectangle with rounded corners
15.	getColor()	Retrieves the current drawing color
16.	getFont()	Retrieves the currently used font
17.	getFontMetrics()	Retrieves the information about the current font
18.	setColor()	Sets the drawing color
19.	setFont()	Sets the font

Lines and Rectangles

Lines are drawn by means of the drawLine() method.

Syntax
void drawLine(int startX, int startY, int endX, int endY)

drawLine() displays a line in the current drawing color that begins at (start X, start Y) and ends at (endX, end Y).

//Drawing Lines import java.awt.*; import java.applet.*; /* <applet code="Lines" width=300 Height=250> </applet> */ public class Lines extends Applet { public void paint(Graphics g) { g.drawLine(0,0,100,100); g.drawLine(0,100,100,0); g.drawLine(40,25,250,180); g.drawLine(5,290,80,19); } }
After this you can comiple your java applet program as shown below:

"Output of Lines.class"

Download Complete Program

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Rectangle

The drawRect() and fillRect() methods display an outlined and filled rectangle, respectively.

Syntax
void drawRect(int top, int left, int width, int height)
void fillRect(int top, int left, int width, int height)

The upper-left corner of the rectangle is at(top,left). The dimensions of the rectangle are specified by width and height.

Use drawRoundRect() or fillRoundRect() to draw a rounded rectangle. A rounded rectangle has rounded corners.

Syntax
void drawRoundRect(int top, int left, int width, int height int Xdiam, int YDiam)
void fillRoundRect(int top, int left, int width, int height int Xdiam, int YDiam)

The upper-left corner of the rounded rectangle is at (top,left). The dimensions of the rectangle are specified by width and height. The diameter of the ribdubg are along the X axis are specified by x Diam. The diameter of the rounding are along the Y axis is specified by Y Diam.

/* =========================================================== File Name : Rectanlge.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.awt.*; import java.applet.*; /* <applet code="Rectanlge" width=300 Height=300> </applet> */ public class Rectanlge extends Applet { public void paint(Graphics g) { g.drawRect(10,10,60,50); g.fillRect(100,100,100,0); g.drawRoundRect(190,10,60,50,15,15); g.fillRoundRect(70,90,140,100,30,40); } }

After this you can comiple your java applet program as shown below:

c:\jdk1.4\bin\javac Rectanlge.java
c:\jdk1.4\bin\appletviewer Rectanlge.java

"Output of Rectangle.class"

Download Complete Program

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Circles and Ellipses

The Graphics class does not contain any method for circles or ellipses. To draw an ellipse, use drawOval(). To fill an ellipse, use fillOval().

Syntax
void drawOval(int top, int left, int width, int height)
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 i.e get height = width.

The following program draws serveral ellipses:
/* =========================================================== File Name : Ellipses.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.awt.*; import java.applet.*; /* <applet code="Ellipses" width=300 Height=300> </applet> */ public class Ellipses extends Applet { public void paint(Graphics g) { g.drawOval(10,10,60,50); g.fillOval(100,10,75,50); g.drawOval(190,10,90,30); g.fillOval(70,90,140,100); } }

After this you can comiple your java applet program as shown below:

c:\jdk1.4\bin\javac Ellipses.java
c:\jdk1.4\bin\appletviewer Ellipses.java

"Output of Ellipses.class"

Download Complete Program

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Drawing Arcs

An arc is a part of oval. Arcs can be drawn with draw Arc() and fillArc() methods.

Syntax
void drawArc(int top, int left, int width, int height, int startAngle, int sweetAngle)
void fillArc(int top, int left, int width, int height, int startAngle, int sweetAngle)

The arc is bounded by the rectangle whose upper-left corner is specified by (top,left) and whose width and height are specified by width and height. The arc is drawn from startAngle through the angular distance specified by sweepAngle. Angles are specified in degree. '0^o' is on the horzontal, at the 30' clock's position. The arc is drawn conterclockwise if sweepAngle is positive, and clockwise if sweetAngle is negative.

The following applet draws several arcs:
/* =========================================================== File Name : Arcs.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.awt.*; import java.applet.*; /* <applet code="Arcs" width=300 Height=300> </applet> */ public class Arcs extends Applet { public void paint(Graphics g) { g.drawArc(10,40,70,70,0,75); g.fillArc(100,40,70,70,0,75); g.drawArc(10,100,70,80,0,175); g.fillArc(100,100,70,90,0,270); g.drawArc(200,80,80,80,0,180); } }

After this you can comiple your java applet program as shown below:

c:\jdk1.4\bin\javac Arcs.java
c:\jdk1.4\bin\appletviewer Arcs.java

"Output of Arcs.class"

Download Complete Program

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Drawing Polygons

Polygons are shapes with many sides. It may be considered a set of lines connected together. The end of the first line is the beginning of the second line, the end of the second line is the beginning of the third line, and so on. Use drawPolygon() and fillPolygon() to draw arbitrarily shaped figures.

Syntax
void drawPolygon(int ,[] , int y[], int numPointer)
void fillPolygon(int ,[] , int y[], int numPointer)

The polygon's endpoints are specified by the coordinate pairs contained within the x and y arrays. The number of points defined by x and y is specified by numPoints.

It is obvious that x and y arrays should be of the same size and we must repeat the first point at the end of the array for closing the polygon.

The following appplet draws an hourglass shape:
/* =========================================================== File Name : Polygon.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.awt.*; import java.applet.*; /* <applet code="Polygon" width=300 Height=300> </applet> */ public class Polygon extends Applet { public void paint(Graphics g) { int xpoints[]={30,200,30,200,30}; int ypoints[]={30,30,200,200,30}; int num=5; g.drawPolygon(xpoints,ypoints,num); } }

After this you can comiple your java applet program as shown below:

c:\jdk1.4\bin\javac Polygon.java
c:\jdk1.4\bin\appletviewer Polygon.java

"Output of Polygon.class"

Download Complete Program

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