Retina-compatible JLabel Image

Question

I have two versions of an image: logo.png (265x150) and [email protected] (530x300). The second one is the retina-version.

In my Java application I have a JLabel on which I'm setting the background to an image like so:

contentPane = new JPanel();
JLabel lblNewLabel = new JLabel("");
lblNewLabel.setBackground(Color.WHITE);
lblNewLabel.setBounds(9, 6, 265, 150);
lblNewLabel.setIcon(new ImageIcon("login_logo.png"));
contentPane.add(lblNewLabel);

This works fine, but I'm not sure how to display the retina-version properly on my Macbook Pro Retina. The retina image isn't scaled resulting in an image that is only partially visible.

Answer 1

My personal opinion would be, first check for retina display, then set the image

 Toolkit.getDefaultToolkit().getDesktopProperty("apple.awt.contentScaleFactor")

The above line will return 2.0 on retina displays. On non-retina macs it will returns 1.0 and on all other platforms null

try following code

public boolean isRatinaDisplay(){
    boolean isRatina = false;
    if (null != Toolkit.getDefaultToolkit().getDesktopProperty("apple.awt.contentScaleFactor") && Float.parseFloat((String) Toolkit.getDefaultToolkit().getDesktopProperty("apple.awt.contentScaleFactor")) == 2.0) {
       //The above line will return 2.0 on retina displays. 
       //On non-retina macs it will returns 1.0 and on all other platforms null
       isRatina = true;
    }
}
JLabel lblLabel = new JLabel("");
if(isRatinaDisplay()){ //if mac set ratina image
  lblLabel.setIcon(new ImageIcon("[email protected]"));
  lblLabel.setSize(new Dimension(530,300));
  lblLabel.setBounds(9, 6, 530,300);
}else{ //else normal
  lblLabel.setSize(new Dimension(265, 150));
  lblLabel.setIcon(new ImageIcon("logo.png"));
  lblLabel.setBounds(9, 6, 265, 150);
}

Answer 2

I think, that you are using two images in different sizes/resolutions. A small one for a display with small resolutions and a bigger one for displays with higher resolution.

A retina display differs from other display essentially in its higher resolution.

So you could try to find out the display resolution and check it that matches to the retina display. There are several possibilities to do that. One could be this: How do you get the screen width in java?

But maybe it would be better to use the size of your JFrame, since that can be in fullscreenmode, or smaller, and the user can change that, as long as you allow that. The size of your JFrame can be determined by this: http://docs.oracle.com/javase/6/docs/api/java/awt/Component.html#getSize()

Another thought: In near future there will be more companies then just apple that provide displays in that solution.

Greetings!

Answer 3

The image is bigger (in terms of width and height in pixels, not in inches) so the JLabel needs to be made bigger (setBounds takes arguments that are measured in pixels, not in inches. This is not actually documented in the Javadocs but it is obvious when you check the Javadocs for setSize).

Java "pixels" aren't real pixels on Apple retina displays. See Swing and bitmaps on retina displays

Also, according to this answer only certain versions of Java support retina displays. I don't know if that's relevant to your problem.