Swing II - Java - page 991

Since both y -coordinates ( Y_MOUTH ) are the same, the line is horizontal. The line for the
mouth begins at coordinates ( X_MOUTH , Y_MOUTH ) and extends to the right for
MOUTH_WIDTH pixels.
The Graphics Class
Every container and component that can be drawn on the screen has an associated
Graphics object. This associated Graphics object has data specifying what area of the
screen the component or container covers. In particular, the Graphics object for a JFrame
specifies that the drawing takes place inside the borders of the JFrame object.
When an object g of the class Graphics is used as the calling object for a drawing method, the
drawing takes place inside the area of the screen specified by g . For example, if g is the
Graphics object for a JFrame , the drawing takes place inside the borders of the JFrame object.
Some of the commonly used methods of the class Graphics are given in Display 18.12.
Graphics is an abstract class in the java.awt package.
Some of the commonly used methods of the class Graphics are given in Display
18.12. Note that most methods come in pairs, one whose name starts with draw and
one whose name starts with fill , such as drawOval and fillOval . The one that starts
with draw will draw the outline of the specified figure. The one that starts with fill
will draw a solid figure obtained by filling the inside of the specified figure. In the next
few subsections we discuss some of these methods.
Display 18.12 Some Methods in the Class Graphics (part 1 of 3)
Graphics is an abstract class in the java.awt package.
Although many of these methods are abstract, we always use them with objects of a concrete
descendent class of Graphics , even though we usually do not know the name of that concrete
class.
public abstract void drawLine( int x1, int y1, int x2, int y2)
Draws a line between points ( x1 , y1 ) and (x 2 , y2 ).
public abstract void drawRect( int x, int y,
int width, int height)
Draws the outline of the specified rectangle. ( x , y ) is the location of the upper-left corner of the
rectangle.
public abstract void fillRect( int x, int y,
int width, int height)
Fills the specified rectangle. (x, y) is the location of the upper-left corner of the rectangle.