Java圖像查看器

MyCanvas.java

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);
}


}   </pre> 


 MyFilter.java 

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; 
    }

}</pre> 


 PictureViewer.java 

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();
        Button select = new Button("選擇圖片");
        previous = new Button("上一張");
        next = new Button("下一張");
        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,"打開文件",FileDialog.LOAD);
        fd_load.setFilenameFilter(filter);
    }

public void actionPerformed(ActionEvent e){
    String command = e.getActionCommand();
    if(command.equals("選擇圖片")){
        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("上一張")){
        findex--;
        if(findex<0)
            findex = 0;
        this.display(files[findex]);
    }else if(command.equals("下一張")){
        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))); 
}

}</pre>