Sizes of frame icons used in Swing

Question

We can use a list to initialise the window icons using Window.setIconImages(List<? extends Image>). What are the different sizes of icons typically used for in a JFrame?

Code

This code turns 64 different sized images (from 16x16, incrementing by 2) into icons for the list.

import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.ArrayList;
import java.util.Vector;
import javax.swing.*;
import javax.swing.border.EmptyBorder;

public class FrameIconList {

    public static BufferedImage getImage(int size, Color color) {
        BufferedImage i = new BufferedImage(
                size, size, BufferedImage.TYPE_INT_RGB);

        Graphics2D g = i.createGraphics();

        g.setColor(color);
        g.fillRect(0, 0, size, size);
        g.setColor(Color.BLACK);
        int off = (size>17 ? 3 : 1);
        if (off>1) g.drawRect(0, 0, size-1, size-1);
        g.drawString("" + size, off, size-off);

        g.dispose();

        return i;
    }

    public static void main(String[] args) {
        final Color[] colors = {
            Color.GREEN,
            Color.RED,
            Color.YELLOW,
            Color.WHITE,
            Color.CYAN,
            Color.MAGENTA,
            Color.PINK,
            Color.ORANGE
        };

        int s = 64;
        final int[] sizes = new int[s];

        for (int ii=0; ii<sizes.length; ii++) {
            sizes[ii] = 16+(ii*2);
        }

        Runnable r = new Runnable() {

            @Override
            public void run() {
                // the GUI as seen by the user (without frame)
                JPanel gui = new JPanel(new BorderLayout());
                gui.setBorder(new EmptyBorder(2, 3, 2, 3));
                gui.setBackground(Color.WHITE);

                ArrayList<BufferedImage> images = new ArrayList<BufferedImage>();
                Vector<ImageIcon> icons = new Vector<ImageIcon>();
                for (int ii=0; ii< sizes.length; ii++) {
                    BufferedImage bi = getImage(
                            sizes[ii], 
                            colors[ii%colors.length]);
                    images.add(bi);
                    ImageIcon imi = new ImageIcon(bi);
                    icons.add(imi);
                }
                JList list = new JList(icons);
                list.setVisibleRowCount(6);
                gui.add(new JScrollPane(list));

                JFrame f = new JFrame("Icon size usage");
                f.setIconImages(images);
                f.add(gui);
                // Ensures JVM closes after frame(s) closed and
                // all non-daemon threads are finished
                f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                // See http://stackoverflow.com/a/7143398/418556 for demo.
                f.setLocationByPlatform(true);

                // ensures the frame is the minimum size it needs to be
                // in order display the components within it
                f.pack();
                // should be done last, to avoid flickering, moving,
                // resizing artifacts.
                f.setVisible(true);
            }
        };
        // Swing GUIs should be created and updated on the EDT
        // http://docs.oracle.com/javase/tutorial/uiswing/concurrency/initial.html
        SwingUtilities.invokeLater(r);
    }
}

Answer 1

Typical views for this Windows 7 based PC

Note: @bobbel reports the same sizes are used for Windows 10.

Frame - 20x20

Task Bar - 40x40 in task bar itself, hover app shows 20x20

Windows+Tab - 20x20

Alt+Tab - 40x40 in lower right, shrunken 20x20 in upper left.

Task Manager - 20x20

Answer 2

@mKorbel Huh.. did not realize there would be a difference there. Well, user/OS preferences rules over programmer expectation! ;)

• answer is only about Win8(ent, 64b ....)/WinXP(not mentioned, but setting are quite similair)

• there are another options please see Bug or feature: Swing default gui font incorrect for Win6+ by @kleopatra, etc

• is possible to set 64x64 icon on desktop in win8

• e.g. my setting (not advanced graphics personalizations, despite the fact that I'm Win2008/12 admin, blablabla- "leaving surealism with reversed color scheme, now only with Black & Orange Colors" -end blablabla)

• generating

• standard setting (only unmarked Use small taskbar buttons)

• your window on my screen

Answer 3

It seems there are no Frame or Dock icons when run in Mac OS X 10.9 (Mavericks):

Also, no icon in Activity Monitor:

Answer 4

Ubuntu 12.04 LTS

The taskbar icon size can be changed between 32 and 64, but all the time uses the 32x32 icon. I have also recompiled the program, but keeps using the same icon.

Taskbar and window (there is not icon at windows).

Alt + Tab

no icon at task manager

Answer 5

I've found out an interesting thing on Win10 (could be also true for Win7 and Win8, but I haven't tried it yet).

By default, Win10 will use image sizes of 20x20 (small) and 40x40 (big).

So, what if you let start your image sizes at 22? It will use image sizes 30x30 (small) and 40x40 (big)!

Generating a whole table of it shows interesting behaviors (tests between tested start sizes result in previous sizes; so 4 will also result in 20x20 and 40x40):

If you start at 2, it will use 20x20 and 40x40.
If you start at 22, it will use 30x30 and 40x40.
If you start at 32, it will use for both 40x40.
If you start at 42, it will use for both 60x60.
If you start at 62, it will use 78x78 and 80x80.
If you start at 80, it will use for both 80x80.
If you start at 82, it will use 98x98 and 120x120.
If you start at 100, it will use 100x100 and 120x120.
If you start at 102, it will use 118x118 and 120x120.
If you start at 120, it will use for both 120x120.
If you start at 122, it will use 138x138 and 158x158.
... okay this is enough ...

I don't really get the pattern behind, but i found it very interesting...

In the end it's really up to you, which sizes you provide. Every OS has it's own logic to show up specific icons. Either it will be scaled up or down if you don't provide the exact image sizes for each OS.