Java Graphics Class

Graphics can be drawn with the help of java applet.

What is Graphics?

  • Graphics are visual images or designs on some surface, such as a wall, canvas, screen, paper, or stone to inform, illustrate, or entertain.
  • Images that are generated by a computer are called computer graphics.
  • Example - photographs, drawings, Line art, graphs, diagrams, typography, numbers, symbols, geometric designs, maps, images.

Graphics using Java Applets

Java applets are written to draw lines,figures of different shapes,images and text in different styles even with the colours in display.

Every applet has it's own area of the screen known as canvas, where it creates the display in the area specified the size of applet's space is decided by the attributes of < applet ..> tag

Co-ordinate system

Coordinate System in Java Graphics

A java applet draws graphical image inside it's space using the coordinate system as shown in above fig.

Java's coordinate system has the origin (0,0) in the upper-left corner, positive x values are to right and positive y values are to the bottom.

These coordinate values of x and y axis are in Pixels.

Graphics Class

The graphics class of java includes methods for drawing different types of shapes,from line to polygons to text in a variety of fonts.

In applet, the paint() method and a Graphics class object is used to display text. To draw shapes on applet graphics class methods are used which of the have arguments representing ends points,corners in the coordinate system.

Drawing Shapes

Java Drawing Shapes

Graphics Class method to draw shapes

Method Name Description
drawRect() This method draws a hollow rectangle
fillRect() This method draws a filled rectangle
drawRoundRect() This method draws a hollow rectangle with rounded corners.
fillRoundRect() This method draws a filled rectangle with rounded corners.
drawPolygon() This method draws a hollow polygon.
fillPolygon() This method draws a filled polygon.
drawOval() This method draws a hollow oval.
fillOval() This method draws a filled oval.
drawArc() This method draws a hollow arc.
fillArc() This method draws a filled arc.
drawLine() This method draws a straight line.
drawString() This method displays a string text.

Graphics Class other method

Method Name Description
copyArea() This method copies a rectangular area of the canvas to another area.
clearRect() This method erases a rectangular are of the canvas.
getColor() It retrives the current drawing colour
getFont() It retrives the currently used font.
getFontMetrics() It retrives information about the current font.
setColor() Sets the drawing color.
setFont() Sets font
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