New Java client properties on Mac

There are a few new client properties on the Mac, that haven’t yet been documented (though I’ve been assured that they’re safe to use). The great thing about the way Apple has been using client properties on the Mac, is that they make it easy for you to get closer to being a great Mac app, while not breaking your fidelity on other platforms. They’re really great if you want to fit in on your target platform, whereas in Mac Widgets for Java, I’m aiming for always looking like a Mac app.

The screenshots above show the new client properties that give you access to SourceList style selection painters (demo’d in the source code below). Note that these painters accurately pick up whether the user is using Aqua or Graphite — that’s a big bonus.

Here’s a listing of the new client properties:

List.sourceListBackgroundPainter
List.sourceListSelectionBackgroundPainter
List.sourceListFocusedSelectionBackgroundPainter
List.evenRowBackgroundPainter
List.oddRowBackgroundPainter

Here’s a little bit of code that puts a few of the new SourceList client properties to work (seen above):

public class NewClientProperties {

    /**
     * Create a SourceList style JList.
     */
    private static JList createMacSourceList() {
        JList list = new SourceList();
        // install a custom renderer that wraps the already installed renderer.
        list.setCellRenderer(new CustomListCellRenderer(list.getCellRenderer()));
        return list;
    }

    /**
     * A custom JList that renders like a Mac SourceList.
     */
    public static class SourceList extends JList {

        public SourceList() {
            // make the component non-opaque so that we can paint the background in
            // paintComponent.
            setOpaque(false);
        }

        @Override
        protected void paintComponent(Graphics g) {
            // paint the background of the component using the special Mac border
            // painter.
            Border backgroundPainter =
                    UIManager.getBorder("List.sourceListBackgroundPainter");
            backgroundPainter.paintBorder(this, g, 0, 0, getWidth(), getHeight());
            super.paintComponent(g);
        }
    }

    /**
     * A custom ListCellRenderrer that wraps a delegate renderer.
     */
    public static class CustomListCellRenderer extends JPanel
            implements ListCellRenderer {

        private ListCellRenderer fDelegate;
        private boolean fIsSelected;
        private boolean fIsFocused;

        public CustomListCellRenderer(ListCellRenderer delegate) {
            this.setOpaque(false);
            this.setLayout(new BorderLayout());
            this.setBorder(BorderFactory.createEmptyBorder(1,5,1,5));
            fDelegate = delegate;
        }

        public Component getListCellRendererComponent(
                JList list, Object value, int index,boolean isSelected,
                boolean cellHasFocus) {

            this.removeAll();
            // remember the isSelected and cellHasFocus state so that we can use those
            // values in the paintComponent method.
            fIsSelected = isSelected;
            fIsFocused = cellHasFocus;
            // call the delegate renderer
            JComponent component = (JComponent) fDelegate.getListCellRendererComponent(
                    list, value, index, isSelected, false);
            // make the delegate rendere non-opqaue so that the background shows through.
            component.setOpaque(false);
            this.add(component, BorderLayout.CENTER);

            return this;
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            // if the item was selected, then paint the custom Mac selection background.
            if (fIsSelected) {
                Border backgroundPainter = fIsFocused
                        ? UIManager.getBorder("List.sourceListFocusedSelectionBackgroundPainter")
                        : UIManager.getBorder("List.sourceListSelectionBackgroundPainter");
                backgroundPainter.paintBorder(this, g, 0, 0, getWidth(), getHeight());
            }
        }
    }

    public static void main(String[] args) {

        JList list = createMacSourceList();
        list.setListData(new String[]{
                "BMW", "Chevy", "Dodge", "Infiniti", "Nissan", "Porsche"});

        JScrollPane scrollPane = new JScrollPane(list);
        scrollPane.setBorder(BorderFactory.createEmptyBorder());

        JFrame frame = new JFrame();
        frame.add(scrollPane);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(200,200);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}