jpanel中图片怎样放大缩小呢？

[able0001]

如果用java做一个类似photoshop的程序，首先载入一副图片，然后，其中一个功能是图形的放大缩小，这应该怎么实现呢，那么是否应该把图像的jpanel放到ScrollPane中，以便出现滚动条？有什么好方法吗？

[yuzl32]

AffineTransformOp

[zouxinfox]

如果想实现图像处理，可以用sun开发的JAI
如果仅仅想实现放大缩小，那么比较简单
这是一个示例，你可以找找灵感
public void CreateThumbnail(Picture oldpicture,Picture newpicture,int maxwidth,int maxheight) throws Exception
{
try {
File F = new File(oldpicture.getImgDir(),oldpicture.getImgfile());
if (!F.isFile())
return;

getImagSize(oldpicture);
double Ratio=getRadio(oldpicture,maxwidth,maxheight);

BufferedImage Bi = ImageIO.read(F);
AffineTransformOp op = new AffineTransformOp(AffineTransform.getScaleInstance(Ratio, Ratio), null);
Image Itemp = op.filter(Bi, null);

File ThF = new File(newpicture.getImgDir(),newpicture.getImgfile());
ImageIO.write((BufferedImage)Itemp, ext, ThF);

}catch (Exception ex) {
throw new Exception(" ImageIo.write error in CreatThum.: "+ex.getMessage());
}

}

public double getRadio(Picture picture,int maxwidth,int maxheight){
double Ratio=1.0;

if (picture.getWidth()>picture.getHeight()){
Ratio = (new Integer(maxwidth)).doubleValue()/picture.getWidth();
}else if (picture.getWidth()<picture.getHeight()){
Ratio=(new Integer(maxheight)).doubleValue()/picture.getHeight();
}else if (picture.getWidth()==picture.getHeight()){
if (picture.getWidth()>maxwidth){
Ratio = (new Integer(maxwidth)).doubleValue()/picture.getWidth();
}

}
return Ratio;
}

public void getImagSize(Picture picture) throws Exception{

double Ratio=1.0;

try{
File F = new File(picture.getImgDir(),picture.getImgfile());
if (!F.isFile())
throw new Exception(F+" is not image file error !");

BufferedImage Bi = ImageIO.read(F);
// Image Itemp = Bi.getScaledInstance (maxwidth,maxheight,Bi.SCALE_SMOOTH);

picture.setWidth(Bi.getWidth());
picture.setHeight(Bi.getHeight());
}catch (Exception ex) {
throw new Exception(" getImagSize: "+ex.getMessage());
}

}

[zclgod]

学习