本文实例讲述了Java实现的图像查看器。分享给大家供大家参考。具体如下:
1. MyCanvas.java:
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package PictureViewer;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
public class MyCanvas extends Canvas implements ComponentListener{
private BufferedImage bi;
private Image im;
private int image_width;
private int image_height;
public void setImage(BufferedImage bi){
this .bi = bi;
this .zoom();
}
public void paint(Graphics g){
g.drawImage(im,( this .getWidth()-image_width)/ 2 ,( this .getHeight()-image_height)/ 2 , this );
}
public void componentResized(ComponentEvent e){
if (bi != null ){
System.out.println( "resize!!" );
this .zoom();
this .repaint();
}
}
public void componentMoved(ComponentEvent e){}
public void componentShown(ComponentEvent e){}
public void componentHidden(ComponentEvent e){}
public void zoom(){
if (bi == null )
return ;
int screen_width = this .getWidth();
int screen_height = this .getHeight();
double screen_proportion = 1.0 * screen_height / screen_width;
System.out.println( "screen: w " +screen_width+ " ,h " +screen_height+ " ,p0 " +screen_proportion);
image_width = bi.getWidth( this );
image_height = bi.getHeight( this );
double image_proportion = 1.0 * image_height / image_width;
System.out.println( "image: w " +image_width+ " ,h " +image_height+ " ,p1 " +image_proportion);
if (image_proportion > screen_proportion){
image_height = screen_height;
image_width = ( int )(image_height / image_proportion);
System.out.println( " p1>p0 w= " +image_width);
} else {
image_width = screen_width;
image_height = ( int )(image_width * image_proportion);
System.out.println( " p0>p1 h= " +image_height);
}
im = bi.getScaledInstance(image_width,image_height,Image.SCALE_SMOOTH);
}
}
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2. MyFilter.java:
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package PictureViewer;
import java.io.File;
import java.io.FilenameFilter;
public class MyFilter implements FilenameFilter{
private String[] extension;
public MyFilter(){
extension = new String[]{ ".jpg" , ".JPG" , ".gif" , ".GIF" , ".png" , ".PNG" , ".jpeg" , ".JPEG" };
}
public MyFilter(String[] extension){
this .extension = extension;
}
public boolean accept(File dir,String name){
for (String s : extension){
if (name.endsWith(s)){
return true ;
}
}
return false ;
}
}
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3. PictureViewer.java:
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package PictureViewer;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.*;
public class PictureViewer implements ActionListener{
private Frame frame;
private MyCanvas mc ;
private String fpath;
private String fname;
private File[] files;
private int findex ;
private FileDialog fd_load;
private MyFilter filter;
private Button previous ;
private Button next ;
public static void main( String args[]) throws Exception {
new PictureViewer().init();
}
public void init(){
frame = new Frame( "PictureViewer" );
Panel pb = new Panel();
previous = new Button( "上一张" );
next = new Button( "下一张" );
select.addActionListener( this );
previous.addActionListener( this );
next.addActionListener( this );
pb.add(select);
pb.add(previous);
pb.add(next);
mc = new MyCanvas();
mc.setBackground( new Color( 200 , 210 , 230 ));
mc.addComponentListener(mc);
frame.add(pb, "North" );
frame.add(mc, "Center" );
frame.setSize( 360 , 360 );
frame.setLocation( 400 , 200 );
frame.addWindowListener( new WindowAdapter(){
public void windowClosing(WindowEvent e){
System.exit( 0 );
}
});
frame.setVisible( true );
this .validateButton();
filter = new MyFilter();
fd_load = new FileDialog(frame, "打开文件" ,FileDialog.LOAD);
fd_load.setFilenameFilter(filter);
}
public void actionPerformed(ActionEvent e){
String command = e.getActionCommand();
if (command.equals( "选择图片" )){
fd_load.setVisible( true );
fpath = fd_load.getDirectory();
fname = fd_load.getFile();
if ((fpath != null ) && (fname != null )){
this .display( new File(fpath + fname));
files = new File(fpath).listFiles(filter);
this .setIndex();
}
} else if (command.equals( "上一张" )){
findex--;
if (findex< 0 )
findex = 0 ;
this .display(files[findex]);
} else if (command.equals( "下一张" )){
findex++;
if (findex >= files.length)
findex = files.length- 1 ;
this .display(files[findex]);
}
this .validateButton();
}
public void display(File f){
try {
BufferedImage bi = ImageIO.read(f);
mc.setImage(bi);
frame.setTitle( "PictureViewer - [" + f.getName() + "]" );
} catch (Exception e){
e.printStackTrace();
}
mc.repaint();
}
public void setIndex(){
File current = new File(fpath + fname);
if (files != null ){
for ( int i= 0 ;i<files.length;i++){
if (current.equals(files[i])){
findex = i;
}
}
}
}
public void validateButton(){
previous.setEnabled((files!= null ) && (findex > 0 ));
next.setEnabled((files!= null ) && (findex<(files.length- 1 )));
}
}
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希望本文所述对大家的java程序设计有所帮助。