RFR: 8276849: Refresh the window icon on graphics configuration changes

[Emmanuel Bourg]

When a list of icons is set on a window, the most appropiate icon is selected depending on the graphics configuration. But if the graphics configuration changes (because the window is moved to a different screen, or because the DPI settings of the screen is changed), the frame icon isn't updated.

Here is an example illustrating the issue:

    public static void main(String[] args) throws Exception {
        SwingUtilities.invokeLater(() -> {
            JFrame frame = new JFrame("Window Icon Test");
            frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
            frame.setSize(400, 300);
            frame.setVisible(true);

            List<Image> images = new ArrayList<>();
            for (int size = 16; size <= 32; size++) {
                // create an image displaying the size used
                BufferedImage image = new BufferedImage(size, size, BufferedImage.TYPE_INT_ARGB);
                Graphics2D g = image.createGraphics();
                g.setFont(new Font("dialog", Font.BOLD, 12));
                g.setColor(Color.BLACK);
                g.drawString(String.valueOf(size), 0, size - (size - g.getFont().getSize()) / 2);
                images.add(image);
            }

            frame.setIconImages(images);
        });
    }

On Windows if the screen scaling is set to 100% the 16x16 icon is picked from the list. If the scaling of the screen is set to 150% while the application is running, the 16x16 icon is upscaled and looks blurry.

A way to work around this issue is to listen for graphics configuration changes with:

    frame.addPropertyChangeListener("graphicsConfiguration", event -> frame.setIconImages(frame.getIconImages()));


Ideally this should be done automatically by the JDK. Maybe the `WindowPeer` could call `updateIconImages()` when `updateGraphicsData()` or `displayChanged()` is invoked?

-------------

Commit messages:
 - Refresh the window icon on graphics configuration changes

Changes: https://git.openjdk.java.net/jdk/pull/6180/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6180&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8276849
  Stats: 4 lines in 3 files changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6180.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6180/head:pull/6180

PR: https://git.openjdk.java.net/jdk/pull/6180