Java scroll indicator with floating scroll bar that appears only when scrolling

Question

I need a scroll bar with scroll bars visible only during scroll events or, if necessary, for pulling. Something like scrollbars on modern smartphones.

I searched a lot, but found only implementations in javascript. So I tried it myself.

Is there a better solution or hints?

Animation classes can be found here: TimingFrameWork

import java.awt.BorderLayout; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics import java.awt.Rectangle; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.AdjustmentEvent; import java.awt.event.AdjustmentListener; import java.awt.event.ComponentAdapter; import java.awt.event.ComponentEvent; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import javax.swing.BorderFactory; import javax.swing.JButton; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JLayeredPane; import javax.swing.JPanel; import javax.swing.JScrollBar; import javax.swing.JScrollPane; import javax.swing.JTextArea; import javax.swing.SwingUtilities; import javax.swing.Timer; import javax.swing.plaf.ScrollBarUI; import javax.swing.plaf.basic.BasicScrollBarUI; import org.jdesktop.animation.timing.Animator; import org.jdesktop.animation.timing.interpolation.KeyFrames; import org.jdesktop.animation.timing.interpolation.KeyTimes; import org.jdesktop.animation.timing.interpolation.KeyValues; import org.jdesktop.animation.timing.interpolation.PropertySetter; /** * A scrollpane like component, where the scroll bars are floating over the * scrollable view to indicate the current scroll positions. * The scroll indicators appear smoothly during scroll events and disappear * smoothly afterwards. * <p> * The scrollbars can be dragged just as normal.</p> * <p> * The usage is similar to a classic scrollpane.</p> * * @author Jolly Littlebottom */ public class JScrollIndicator extends JLayeredPane { private static final Color THUMB_COLOR = Color.DARK_GRAY; private static final Color THUMB_BORDER_COLOR = Color.LIGHT_GRAY; private static final float MAX_ALPHA = 0.8f; private static final int THUMB_THICKNESS = 7; private static final int THUMB_MIN_SIZE = 48; private static final int THUMB_MARGIN = 3; private static final int FADE_IN_TIME = 300; private static final int STAY_TIME = 2000; private static final int FADE_OUT_TIME = 1000; private final JScrollPane scrollPane; private final ControlPanel controlPanel; /** * Creates a <code>JScrollIndicator</code> that displays the contents of the * specified component, where both horizontal and vertical scrollbars appear * whenever the component contents are larger than the view and scrolling * in underway or the mouse is over the scrollbar position. * * @see #setViewportView * @param view the component to display in the scrollpane viewport */ public JScrollIndicator(final JComponent view) { this(view, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED); } /** * Creates a <code>JScrollIndicator</code> that displays the view component * in a viewport whose view position can be controlled with a pair of * scrollbars. * The scrollbar policies specify when the scrollbars are displayed, * For example, if <code>vsbPolicy</code> is * <code>JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED</code> * then the vertical scrollbar only appears if the view doesn't fit * vertically. The available policy settings are listed at * {@link #JScrollPane.setVerticalScrollBarPolicy} and * {@link #JScrollPane.setHorizontalScrollBarPolicy}. * * @param view the component to display in the scrollpanes viewport * @param vsbPolicy an integer that specifies the vertical scrollbar policy * @param hsbPolicy an integer that specifies the horizontal scrollbar policy */ public JScrollIndicator(final JComponent view, int vsbPolicy, int hsbPolicy) { scrollPane = new JScrollPane(view, vsbPolicy, hsbPolicy); scrollPane.setBorder(BorderFactory.createEmptyBorder()); add(scrollPane, JLayeredPane.DEFAULT_LAYER); controlPanel = new ControlPanel(scrollPane); add(controlPanel, JLayeredPane.PALETTE_LAYER); addComponentListener(new ComponentAdapter() { @Override public void componentResized(ComponentEvent e) { // listen to changes of JLayeredPane size scrollPane.setSize(getSize()); scrollPane.getViewport().revalidate(); controlPanel.setSize(getSize()); controlPanel.revalidate(); } }); } /** * Returns the scroll pane used by this scroll indicator. * Use carefully (eg to set unit increments) because not all changes have an * effect. You have to write listeners in this cases (eg for changing the * scrollbar policy) * * @return */ public JScrollPane getScrollPane() { return scrollPane; } private class ControlPanel extends JPanel { private final JMyScrollBar vScrollBar; private final JMyScrollBar hScrollBar; private ControlPanel(JScrollPane scrollPane) { setLayout(new BorderLayout()); setOpaque(false); vScrollBar = new JMyScrollBar(JScrollBar.VERTICAL); scrollPane.setVerticalScrollBar(vScrollBar); scrollPane.remove(vScrollBar); if (scrollPane.getVerticalScrollBarPolicy() != JScrollPane.VERTICAL_SCROLLBAR_NEVER) { add(vScrollBar, BorderLayout.EAST); } hScrollBar = new JMyScrollBar(JScrollBar.HORIZONTAL); scrollPane.setHorizontalScrollBar(hScrollBar); scrollPane.remove(hScrollBar); if (scrollPane.getHorizontalScrollBarPolicy() != JScrollPane.HORIZONTAL_SCROLLBAR_NEVER) { add(hScrollBar, BorderLayout.SOUTH); } } } private class JMyScrollBar extends JScrollBar { protected final MyScrollBarUI scrollUI; public JMyScrollBar(int direction) { super(direction); scrollUI = new MyScrollBarUI(this); super.setUI(scrollUI); int size = THUMB_THICKNESS + THUMB_MARGIN; setPreferredSize(new Dimension(size, size)); addMouseListener(new MouseAdapter() { @Override public void mouseEntered(MouseEvent e) { scrollUI.setVisible(true, true); } @Override public void mouseExited(MouseEvent e) { scrollUI.setVisible(false, false); } }); addAdjustmentListener(new AdjustmentListener() { @Override public void adjustmentValueChanged(AdjustmentEvent e) { scrollUI.setVisible(true, false); } }); } @Override public void setUI(ScrollBarUI ui) { } @Override public void updateUI() { } @Override public void paint(Graphics g) { scrollUI.paintThumb(g, this); // just the thumb } @Override public void repaint(Rectangle r) { JScrollIndicator scrollIndicator = JScrollIndicator.this; Rectangle rect = SwingUtilities.convertRectangle(this, r, scrollIndicator); rect.grow(1, 1); // ensure for a translucent thumb, that the view is first painted scrollIndicator.repaint(rect); } } public class MyScrollBarUI extends BasicScrollBarUI { private JMyScrollBar scrollBar; private float alpha = 0.0f; private FadeAnimation fadeAnimation; private MyScrollBarUI(JMyScrollBar scrollBar) { this.scrollBar = scrollBar; fadeAnimation = new FadeAnimation(this); } @Override protected void installComponents() { incrButton = new JButton(); decrButton = new JButton(); if (scrollBar.getOrientation() == JScrollBar.HORIZONTAL) { int size = THUMB_THICKNESS + THUMB_MARGIN; // let lower right corner empty incrButton.setPreferredSize(new Dimension(size, size)); } else { incrButton.setPreferredSize(new Dimension(THUMB_MARGIN, THUMB_MARGIN)); } decrButton.setPreferredSize(new Dimension(THUMB_MARGIN, THUMB_MARGIN)); } @Override protected void installDefaults() { super.installDefaults(); // ensure the minimum size of the thumb int w = minimumThumbSize.width; int h = minimumThumbSize.height; if (scrollBar.getOrientation() == JScrollBar.VERTICAL) { h = Math.max(h, Math.min(maximumThumbSize.height, THUMB_MIN_SIZE)); } else { w = Math.max(w, Math.min(maximumThumbSize.width, THUMB_MIN_SIZE)); } minimumThumbSize = new Dimension(w, h); } private void paintThumb(Graphics g, JComponent c) { if (alpha == 0.0f) { return; // don't paint anything } g.setColor(getAlphaColor(THUMB_COLOR)); int radius = THUMB_THICKNESS >>> 1; // half width Rectangle thumbBounds = getThumbBounds(); int x = thumbBounds.x; int y = thumbBounds.y; int w = thumbBounds.width; int h = thumbBounds.height; if (scrollBar.getOrientation() == JScrollBar.VERTICAL) { w -= THUMB_MARGIN; } else { h -= THUMB_MARGIN; } g.fillRoundRect(x, y, w, h, radius, radius); g.setColor(getAlphaColor(THUMB_BORDER_COLOR)); g.drawRoundRect(x, y, w, h, radius, radius); } private Color getAlphaColor(Color color) { if (alpha == 1.0f) { return color; } int rgb = color.getRGB() & 0xFFFFFF; // color without alpha values rgb |= ((int)(alpha*255)) << 24; // add alpha value return new Color(rgb, true); } public void setAlpha(float alpha) { this.alpha = alpha; scrollBar.repaint(getThumbBounds()); } public void setVisible(boolean visible, boolean mouseOver) { if (visible) { fadeAnimation.fadeIn(mouseOver); } else { fadeAnimation.fadeOut(); } scrollBar.repaint(getThumbBounds()); } } private class FadeAnimation { private final MyScrollBarUI scrollUI; private Animator fadeAnimator; private Timer fadeOutTimer; private boolean isFadeIn; private FadeAnimation(MyScrollBarUI scrollUI) { this.scrollUI = scrollUI; } public synchronized void fadeIn(boolean mouseOver) { if (mouseOver) { cancelTimer(); } if (!isFadeIn) { isFadeIn = true; cancelAnimationAndTimer(); fadeAnimator = PropertySetter.createAnimator( FADE_IN_TIME, scrollUI, "alpha", new KeyFrames(KeyValues.create(scrollUI.alpha, MAX_ALPHA), new KeyTimes(0.0f, 1.0f))); fadeAnimator.start(); if (!mouseOver) { fadeOutTimer = new Timer(FADE_IN_TIME + STAY_TIME, new ActionListener() { @Override public void actionPerformed(ActionEvent e) { FadeAnimation.this.fadeOut(); } }); fadeOutTimer.start(); } } } public synchronized void fadeOut() { cancelAnimationAndTimer(); if (isFadeIn) { isFadeIn = false; fadeAnimator = PropertySetter.createAnimator( FADE_OUT_TIME, scrollUI, "alpha", new KeyFrames(KeyValues.create(scrollUI.alpha, 0.0f), new KeyTimes(0.0f, 1.0f))); fadeAnimator.start(); } } private void cancelAnimationAndTimer() { if (fadeAnimator != null && fadeAnimator.isRunning()) { fadeAnimator.cancel(); fadeAnimator = null; } cancelTimer(); } private void cancelTimer() { if (fadeOutTimer != null) { fadeOutTimer.stop(); fadeOutTimer = null; } } } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { @Override public void run() { JFrame frame = new JFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); String text = ""; for (int i = 0; i < 100; i++) { for (int j = 0; j < 100; j++) { text += i + " - " + j; } text += "\n"; } JTextArea area = new JTextArea(text); JScrollIndicator scrollIndicator = new JScrollIndicator(area); frame.getContentPane().add(scrollIndicator); frame.setBounds(100, 100, 200, 300); frame.setVisible(true); } }); } }