Java

Question

如果图像太大，我想调整它的大小，但我希望它保持纵横比，我怎样才能定义它的高度并让它自动获得它的宽度？

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

你应该做一些maths.find高度和旧高度的比例然后找到新的宽度

double Width=(200/(double)image2.getIconHeight())*image2.getIconWidth();

然后你可以设置宽度

Image newimg = img.getScaledInstance( Width, 200,  java.awt.Image.SCALE_SMOOTH ) ;

Answer 2

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 ) ;

Java - 如何为 img.getScaledInstance( ); 自动设置宽度？

Java - how to auto set width for img.getScaledInstance( );?

height

resize