import javax.swing.*; import javax.swing.event.AncestorListener; import java.awt.*; import java.awt.event.*; /** * Test instructions: * Click the "Simulate Swipe" button. Look in the console for "Swipe simulation took X ms". * If x is under 500ms, then this test passes. If it is over 500s, then this test fails. *

* On my MacBook Pro this took 1,762ms. If I deselect "Include AncestorListeners", then the * simulation takes 103ms. I expect it to always be closer to 100ms than 1.7s */ public class ScrollingButtonPanelTest extends JPanel { public static void main(String[] args) { SwingUtilities.invokeLater(() -> { JFrame f = new JFrame(); f.getContentPane().add(new ScrollingButtonPanelTest()); f.pack(); f.setVisible(true); }); } static final int NUMBER_OF_CHECKBOXES = 1000; private static final String PROPERTY_ORIGINAL_ANCESTOR_LISTENERS = "originalAncestorListeners"; JScrollPane scrollPane; JCheckBox includeAncestorListenerButton = new JCheckBox("Include AncestorListeners", true); JPanel scrollPaneContent = new JPanel(new GridLayout(NUMBER_OF_CHECKBOXES, 1)); record ScrollMovement(int wheelRotation, double preciseWheelRotation, long when) {}; /** * These describe the MouseWheelEvents I observed when I swiped down over the scrollpane using * my MacBook's touchpad. */ ScrollMovement[] swipeMovements = new ScrollMovement[] { new ScrollMovement(0, 0.4, -1), new ScrollMovement(1, 0.5, 0), new ScrollMovement(6, 6.5, 15), new ScrollMovement(0, 0.1, 15), new ScrollMovement(12, 11.600000000000001, 30), new ScrollMovement(12, 12.3, 49), new ScrollMovement(13, 12.3, 63), new ScrollMovement(11, 11.8, 82), new ScrollMovement(12, 11.3, 97), new ScrollMovement(10, 10.700000000000001, 113), new ScrollMovement(11, 10.3, 130), new ScrollMovement(9, 9.700000000000001, 147), new ScrollMovement(10, 9.3, 163), new ScrollMovement(9, 8.9, 182), new ScrollMovement(8, 8.4, 197), new ScrollMovement(8, 7.9, 214), new ScrollMovement(7, 7.4, 233), new ScrollMovement(7, 7.0, 249), new ScrollMovement(7, 6.4, 265), new ScrollMovement(6, 6.0, 281), new ScrollMovement(5, 5.7, 298), new ScrollMovement(6, 5.300000000000001, 315), new ScrollMovement(5, 4.9, 331), new ScrollMovement(4, 4.5, 348), new ScrollMovement(4, 4.1000000000000005, 365), new ScrollMovement(4, 3.9000000000000004, 382), new ScrollMovement(4, 3.5, 399), new ScrollMovement(3, 3.3000000000000003, 415), new ScrollMovement(3, 3.0, 431), new ScrollMovement(3, 2.8000000000000003, 449), new ScrollMovement(2, 2.6, 465), new ScrollMovement(3, 2.2, 481), new ScrollMovement(2, 2.1, 498), new ScrollMovement(2, 1.9000000000000001, 515), new ScrollMovement(1, 1.7000000000000002, 532), new ScrollMovement(2, 1.6, 548), new ScrollMovement(1, 1.4000000000000001, 565), new ScrollMovement(2, 1.3, 582), new ScrollMovement(1, 1.2000000000000002, 599), new ScrollMovement(1, 1.1, 615), new ScrollMovement(1, 1.0, 632), new ScrollMovement(1, 0.9, 649), new ScrollMovement(1, 0.9, 666), new ScrollMovement(0, 0.8, 682), new ScrollMovement(1, 0.7000000000000001, 699), new ScrollMovement(1, 0.7000000000000001, 716), new ScrollMovement(0, 0.6000000000000001, 733), new ScrollMovement(1, 0.6000000000000001, 749), new ScrollMovement(1, 0.5, 766), new ScrollMovement(0, 0.5, 783), new ScrollMovement(1, 0.5, 800), new ScrollMovement(0, 0.4, 817), new ScrollMovement(0, 0.4, 834), new ScrollMovement(1, 0.4, 849), new ScrollMovement(0, 0.30000000000000004, 865), new ScrollMovement(0, 0.30000000000000004, 883), new ScrollMovement(1, 0.30000000000000004, 899), new ScrollMovement(0, 0.30000000000000004, 916), new ScrollMovement(0, 0.2, 933), new ScrollMovement(0, 0.2, 949), new ScrollMovement(1, 0.2, 966), new ScrollMovement(0, 0.2, 983), new ScrollMovement(0, 0.1, 998), new ScrollMovement(0, 0.1, 1017), new ScrollMovement(0, 0.1, 1033), new ScrollMovement(0, 0.1, 1049), new ScrollMovement(0, 0.1, 1067), new ScrollMovement(0, 0.1, 1100), new ScrollMovement(0, 0.1, 1117), new ScrollMovement(1, 0.1, 1134) }; public ScrollingButtonPanelTest() { JButton simulateSwipeButton = new JButton("Simulate Swipe"); simulateSwipeButton.setToolTipText("Simulate scrolling as if swiping two fingers across a touchpad."); simulateSwipeButton.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { long startTime = System.currentTimeMillis(); for (ScrollMovement m : swipeMovements) { MouseWheelEvent event = new MouseWheelEvent( scrollPane, MouseWheelEvent.MOUSE_WHEEL, m.when + startTime, 0, 50, 50, 50, 50, 0, false, MouseWheelEvent.WHEEL_UNIT_SCROLL, 1, m.wheelRotation, m.preciseWheelRotation); Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(event); } SwingUtilities.invokeLater(new Runnable() { @Override public void run() { SwingUtilities.invokeLater(new Runnable() { @Override public void run() { System.out.println("Swipe simulation took " + (System.currentTimeMillis() - startTime) + " ms"); } }); } }); } }); scrollPane = new JScrollPane(scrollPaneContent); for (int a = 1; a <= NUMBER_OF_CHECKBOXES; a++) { JCheckBox checkbox = new JCheckBox("Checkbox " + a); scrollPaneContent.add(checkbox); checkbox.putClientProperty(PROPERTY_ORIGINAL_ANCESTOR_LISTENERS, checkbox.getAncestorListeners()); } scrollPane.setPreferredSize(new Dimension(800, 400)); setLayout(new BorderLayout()); add(scrollPane, BorderLayout.CENTER); add(simulateSwipeButton, BorderLayout.NORTH); add(includeAncestorListenerButton, BorderLayout.SOUTH); includeAncestorListenerButton.setToolTipText("Toggling off AncestorListeners resolves the performance complaint demonstrated here."); includeAncestorListenerButton.addActionListener(e -> { for (Component c : scrollPaneContent.getComponents()) { JComponent jc = (JComponent) c; AncestorListener[] listeners = (AncestorListener[]) jc.getClientProperty(PROPERTY_ORIGINAL_ANCESTOR_LISTENERS); for (AncestorListener listener : listeners) { if (includeAncestorListenerButton.isSelected()) { jc.addAncestorListener(listener); } else { jc.removeAncestorListener(listener); } } } }); } }