我需要一个滚动窗格，其滚动条仅在滚动事件期间或需要拉动时可见。看起来像当今智能手机上的滚动条。
我搜索了很多，但只找到了 javascript 中的实现。所以我自己试了一下。
有没有更好的解决方案或提示？
动画类可以在这里找到：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's 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's 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 (e.g. to set unit increments) because not all changes have an
* effect. You have to write listeners in this cases (e.g. 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);
}
});
}
}