Java Reference
In-Depth Information
To use
Area
, first pass a
Shape
object to its
Area(Shape s)
constructor and
theninvokeoneoftheaforementionedmethodsonthis
Area
objecttoperformtheop-
eration.Because
Area
alsoimplements
Shape
,youcanpassthe
Area
objectwiththe
Boolean result to
Graphics2D
's
draw()
and
fill()
methods.
The following example demonstrates the union operation on a pair of ellipses:
Ellipse2D ell1 = new Ellipse2D.Double(10.0, 10.0, 40.0,
40.0);
Ellipse2D ell2 = new Ellipse2D.Double(30.0, 10.0, 40.0,
40.0);
Area area1 = new Area(ell1);
Area area2 = new Area(ell2);
area1.add(area2);
Aftercreatingtwoellipseshapes,theexamplecreatestwo
Area
objects,whereeach
objectcontainsoneellipse.Ittheninvokes
add()
onthefirst
Area
objecttocreatea
unionofpixelsinthearearangingfromupper-leftcorner(
10.0
,
10.0
)tolower-right
corner (
70.0
,
50.0
). The result is stored in the first
Area
object.
I'vecreatedaCAGapplicationthatdemonstratestheseBooleanoperations—theap-
plication'ssourcecodeisavailableinthisbook'saccompanyingcodefile.Thisapplica-
tion's output appears in
Figure 7-27
.
Figure 7-27.
Press the mouse pointer over the round rectangle to begin dragging this
shape.
Buffered Images
AWT's
Image
classassociateswitharectangulararrayofcoloredpixels.Althoughyou
can draw these pixels (via
drawImage()
), you need to work with AWT's somewhat
tedious producer/consumer model (which I don't discuss for brevity) to access them.
In contrast, Java 2D's
java.awt.image.BufferedImage
class, which extends
Image
, makes these pixels available to applications and is easier to use.
