Java - 如何自动设置 img.getScaledInstance( ); 的宽度？

Question

如果图像太大，我想调整图像的大小，但我希望它保持其纵横比，我怎样才能定义它的高度并让它自动获取它的宽度？

ImageIcon image2 = new ImageIcon(image);

//Check if image size is more than 200

if(!checking){
    Image img = image2.getImage() ;  
    Image newimg = img.getScaledInstance( "What to put here?", 200,  java.awt.Image.SCALE_SMOOTH ) ;  
    image2 = new ImageIcon( newimg );
}   

JButton newimage = new JButton(image2);

Answer 1

复制自 Javadocs ,

If either width or height is a negative number then a value is substituted to maintain the aspect ratio of the original image dimensions. If both width and height are negative, then the original image dimensions are used.

所以你可以这样做，

img.getScaledInstance(-1, 200,  java.awt.Image.SCALE_SMOOTH ) ;