Page 190 - The Definitive Guide to Building Java Robots

Preston_5564C06.fm Page 171 Friday, September 23, 2005 5:13 AM

CHAPTER 6 ■ VISION 171

public void paint(Graphics g) {
if (image != null) {
// in case image resizes background is black
g.setColor(Color.BLACK);
g.fillRect(0,0,this.getWidth(),getHeight());
g.drawImage(image, 0, 0, this);
}
}
}
Now that I have a canvas to work with, it’s time to create my ImageViewer class. This class
has a single field, currentImage of type BufferedImage. There are two constructors, one taking
a BufferedImage as a parameter, and the other taking a filename. In the second constructor to
get a JPEG file, I open a FileInputStream, then pass this object to the JPEGImageDecoder, then
call the decodeAsBufferedImage() method setting the currentImage. Once its construction is
finished, I call init().
In the init() method, I get the size of the image, and then construct an ImagePanel with
those dimensions. Next, I set the size of the window with enough room for the borders and title
bar. Once sized, I add the ImagePanel to the content pane of the frame, make it visible, and
then set the image into the ImagePanel. See Example 6-5 and Figure 6-3.

Figure 6-3. The ImageViewer

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