Making Bricks
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Brick Applet: Obviously you could make this little applet
using calls to fillRect without any need to create images, but the point of
this demonstration applet if for you to see how to create an image and set
the pixels in that image. So, you will need to study the explanations
provided down on the page in order to create this applet.
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There are a few things you need to be aware of inorder to successfully
complete this applet:
First Item: You need to do a special import for
java.awt.image.*
import.awt.image.*;
Second Item:
You need to declare two instances of the Image class before the init method:
Image red_brick, yellow_brick;
Third Item:
You need to define your two instances of the image class in the init method:
red_brick=makeBrick(20,10,1);
yellow_brick=makeBrick(20,10,2);
Fourth Item:
You need to create a method which defines all the pixels for your bricks:
<![CDATA[
public Image makeBrick(int w, int h, int color){
int pixels[] = new int[w*h];
for(int i = 0; i<w*h; i++){
if(color==1) pixels[i]=Color.red.getRGB();
else pixels[i]=Color.yellow.getRGB();
}
return createImage(new MemoryImageSource(w,h,pixels,0,w));
}
}
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<![CDATA[
EXPLANATION: You should first notice that the pixels array is used in the
call to MemoryImageSource. Before this call you populate the pixels array
with integer values which represent color values. The integer values for
colors can be returned using the getRGB() method in the java.awt.Color
class. This makes it easy to determine the integer value for a particular
color.
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Fifth Item:
You need to call the drawImage method in your paint method. The drawImage
takes four arguments. The first is the image to be drawn. The next two
designate the upper-left corner of the image in the applet area. The last
one has to be an instance of the ImageObserver class. An applet qualifies as
an ImageObserver.
<![CDATA[
public void paint(Graphics g){
g.drawImage(red_brick, 10, 10, this);
g.drawImage(yellow_brick, 60, 10, this);
}
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