大家帮我看看！为什么Image.getWidth(this)为什么要this?

[cykabc]

[b]import java.awt.*;
import java.io.*;
import javax.imageio.*;
import javax.swing.*;

/**
* @version 1.33 2007-04-14
* @author Cay Horstmann
*/
public class ImageTest
{
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
ImageFrame frame = new ImageFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
});
}
}

/**
* A frame with an image component
*/
class ImageFrame extends JFrame
{
public ImageFrame()
{
setTitle("ImageTest");
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

// add component to frame

ImageComponent component = new ImageComponent();
add(component);
}

public static final int DEFAULT_WIDTH = 300;
public static final int DEFAULT_HEIGHT = 200;
}

/**
* A component that displays a tiled image
*/
class ImageComponent extends JComponent
{
public ImageComponent()
{
// acquire the image
try
{
image = ImageIO.read(new File("blue-ball.gif"));
}
catch (IOException e)
{
e.printStackTrace();
}
}

public void paintComponent(Graphics g)
{
if (image == null) return;

int imageWidth = image.getWidth(this);
int imageHeight = image.getHeight(this);

// draw the image in the upper-left corner

g.drawImage(image, 0, 0, null);
// tile the image across the component

for (int i = 0; i * imageWidth <= getWidth(); i++)
for (int j = 0; j * imageHeight <= getHeight(); j++)
if (i + j > 0) g.copyArea(0, 0, imageWidth, imageHeight, i * imageWidth, j
* imageHeight);
}

private Image image;
}

[cykabc]

是因为变量Image包含了一个封装图像数据的对象引用吗？请大神给解释一下！

[xxxxJustDoIt]

参考这里看看，这是大神总结的，转下 http://blog.csdn.net/fzfengzhi/article/details/2174406

[LCore]

引用 楼主 cykabc 的回复:

[b]import java.awt.*; import java.io.*; import javax.imageio.*; import javax.swing.*; /** * @version 1.33 2007-04-14 * @author Cay Horstmann */ public class ImageTest { ……

查阅api其getHeght方法原型如下: public abstract int getHeight(ImageObserver observer) 那么ImageObserver 是个什么东东? ImageObserver observer;： 一个实现ImageObserver接口的对象。它将该对象登记为一个图像观察者， 因此当图像的任何新信息可见时它被通知.

[cykabc]

谢谢，我刚才也查看了！