英文:
How can I stop JLabel scaling an image?
问题
我有一个Swing应用程序，可以通过将图像加载到JLabel中来显示图像。在Java 8之前，这个功能正常工作。自从Java 9以来，有一些变化旨在使应用程序在更高像素密度下调整大小，包括重新调整图像大小：当像素密度较高时，图像会被放大。结果在许多情况下都很不美观。例如，如果我有一张像素高的照片，我的应用程序会将其缩小以适应可用空间，但然后它会自动放大，以适应更高的像素密度 - 看起来很丑。
我可以看到有几种避免这个问题的方法：
- 实现
java.awt.image.MultiResolutionImage接口，看起来应该有帮助，但我不知道如何在JLabel中使用它。 - 也许有一种方法可以欺骗Swing，让它认为不需要进行任何像素缩放，但我找不到类似的方法。
以下代码是一个简单的示例，展示了如何在标签中显示图像。在Java 8中，图像以像素为单位显示。在Java 9+中，整个UI，包括图像在内，会根据您的操作系统认为的像素密度进行放大。您应该能够显式设置此缩放 - Windows 10中可以在“显示”、“缩放和布局”下找到此选项。我的设置为125%，这似乎是一个完美的数值，可以使几乎任何图像看起来都不美观。
import java.awt.*;
import javax.imageio.*;
import javax.swing.*;
import java.io.*;
public class Img extends JFrame {
public static void main(String[] args) throws IOException {
new Img(new File(args[0]));
}
private Img(File file) throws IOException {
super("Img: " + file.getName());
ImageIcon img = new ImageIcon(ImageIO.read(file));
JLabel label = new JLabel(img);
label.setPreferredSize(new Dimension(img.getIconWidth(), img.getIconHeight()));
add(label);
setDefaultCloseOperation(EXIT_ON_CLOSE);
pack();
setVisible(true);
}
}
英文:
I have a Swing app that can display an image by loading it into a JLabel. Up to Java 8, this worked fine. Since Java 9 there are changes intended to make apps resize on higher pixel densities, including rescaling images: when pixel density is high, images are scaled up. The results are ugly in many cases. As an example, if I have a photo with a high pixel count, my app scales it down to fit the available space, but then it's automatically scaled back up to allow for the higher pixel density - ugly.
A couple of options I can see for avoiding this problem are:
- Implementing the interface
java.awt.image.MultiResolutionImagewhich looks like it should help, but I don't see how to use that withJLabel. - Maybe there's a way to fool Swing into thinking that no pixel scaling is necessary, but I can't find anything like that
The following code is a simple example of displaying an image in a label. In Java 8, the image is displayed pixel-for-pixel. In Java 9+, the whole UI including the image is scaled up according to what your OS thinks is your pixel density. You should be able to set this scaling explicitly - Windows 10 has it under "Display", "Scale and Layout". Mine is set to 125% which seems to be a perfect amount to make almost any image look ugly.
import java.awt.*;
import javax.imageio.*;
import javax.swing.*;
import java.io.*;
public class Img extends JFrame {
public static void main( String[] args ) throws IOException {
new Img( new File( args[0] ) );
}
private Img( File file ) throws IOException {
super( "Img: " + file.getName () );
ImageIcon img = new ImageIcon( ImageIO.read( file ) );
JLabel label = new JLabel( img );
label.setPreferredSize( new Dimension( img.getIconWidth(), img.getIconHeight() ) );
add( label );
setDefaultCloseOperation( EXIT_ON_CLOSE );
pack();
setVisible( true );
}
}
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