问题
How can I implement Marquee effect in Java Swing
回答1:
Here's an example using javax.swing.Timer.
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
/** @see http://stackoverflow.com/questions/3617326 */
public class MarqueeTest {
private void display() {
JFrame f = new JFrame("MarqueeTest");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
String s = "Tomorrow, and tomorrow, and tomorrow, "
+ "creeps in this petty pace from day to day, "
+ "to the last syllable of recorded time; ... "
+ "It is a tale told by an idiot, full of "
+ "sound and fury signifying nothing.";
MarqueePanel mp = new MarqueePanel(s, 32);
f.add(mp);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
mp.start();
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new MarqueeTest().display();
}
});
}
}
/** Side-scroll n characters of s. */
class MarqueePanel extends JPanel implements ActionListener {
private static final int RATE = 12;
private final Timer timer = new Timer(1000 / RATE, this);
private final JLabel label = new JLabel();
private final String s;
private final int n;
private int index;
public MarqueePanel(String s, int n) {
if (s == null || n < 1) {
throw new IllegalArgumentException("Null string or n < 1");
}
StringBuilder sb = new StringBuilder(n);
for (int i = 0; i < n; i++) {
sb.append(' ');
}
this.s = sb + s + sb;
this.n = n;
label.setFont(new Font("Serif", Font.ITALIC, 36));
label.setText(sb.toString());
this.add(label);
}
public void start() {
timer.start();
}
public void stop() {
timer.stop();
}
@Override
public void actionPerformed(ActionEvent e) {
index++;
if (index > s.length() - n) {
index = 0;
}
label.setText(s.substring(index, index + n));
}
}
回答2:
I know this is a late answer, but I just saw another question about a marquee that was closed because it was considered a duplicate of this answer.
So I thought I'd add my suggestion which takes a approach different from the other answers suggested here.
The MarqueePanel scrolls components on a panel not just text. So this allows you to take full advantage of any Swing component. A simple marquee can be used by adding a JLabel with text. A fancier marquee might use a JLabel with HTML so you can use different fonts and color for the text. You can even add a second component with an image.
回答3:
Basic answer is you draw your text / graphic into a bitmap and then implement a component that paints the bitmap offset by some amount. Usually marquees / tickers scroll left so the offset increases which means the bitmap is painted at -offset. Your component runs a timer that fires periodically, incrementing the offset and invalidating itself so it repaints.
Things like wrapping are a little more complex to deal with but fairly straightforward. If the offset exceeds the bitmap width you reset it back to 0. If the offset + component width > bitmap width you paint the remainder of the component starting from the beginning of the bitmap.
The key to a decent ticker is to make the scrolling as smooth and as flicker free as possible. Therefore it may be necessary to consider double buffering the result, first painting the scrolling bit into a bitmap and then rendering that in one go rather than painting straight into the screen.
回答4:
Here is some code that I threw together to get you started. I normally would take the ActionListener code and put that in some sort of MarqueeController class to keep this logic separate from the panel, but that's a different question about organizing the MVC architecture, and in a simple enough class like this it may not be so important.
There are also various animation libraries that would help you do this, but I don't normally like to include libraries into projects only to solve one problem like this.
public class MarqueePanel extends JPanel {
private JLabel textLabel;
private int panelLocation;
private ActionListener taskPerformer;
private boolean isRunning = false;
public static final int FRAMES_PER_SECOND = 24;
public static final int MOVEMENT_PER_FRAME = 5;
/**
* Class constructor creates a marquee panel.
*/
public MarqueePanel() {
this.setLayout(null);
this.textLabel = new JLabel("Scrolling Text Here");
this.panelLocation = 0;
this.taskPerformer = new ActionListener() {
public void actionPerformed(ActionEvent evt) {
MarqueePanel.this.tickAnimation();
}
}
}
/**
* Starts the animation.
*/
public void start() {
this.isRunning = true;
this.tickAnimation();
}
/**
* Stops the animation.
*/
public void stop() {
this.isRunning = false;
}
/**
* Moves the label one frame to the left. If it's out of display range, move it back
* to the right, out of display range.
*/
private void tickAnimation() {
this.panelLocation -= MarqueePanel.MOVEMENT_PER_FRAME;
if (this.panelLocation < this.textLabel.getWidth())
this.panelLocaton = this.getWidth();
this.textLabel.setLocation(this.panelLocation, 0);
this.repaint();
if (this.isRunning) {
Timer t = new Timer(1000 / MarqueePanel.FRAMES_PER_SECOND, this.taskPerformer);
t.setRepeats(false);
t.start();
}
}
}
回答5:
Add a JLabel to your frame or panel.
ScrollText s= new ScrollText("ello Everyone.");
jLabel3.add(s);
public class ScrollText extends JComponent {
private BufferedImage image;
private Dimension imageSize;
private volatile int currOffset;
private Thread internalThread;
private volatile boolean noStopRequested;
public ScrollText(String text) {
currOffset = 0;
buildImage(text);
setMinimumSize(imageSize);
setPreferredSize(imageSize);
setMaximumSize(imageSize);
setSize(imageSize);
noStopRequested = true;
Runnable r = new Runnable() {
public void run() {
try {
runWork();
} catch (Exception x) {
x.printStackTrace();
}
}
};
internalThread = new Thread(r, "ScrollText");
internalThread.start();
}
private void buildImage(String text) {
RenderingHints renderHints = new RenderingHints(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
renderHints.put(RenderingHints.KEY_RENDERING,
RenderingHints.VALUE_RENDER_QUALITY);
BufferedImage scratchImage = new BufferedImage(1, 1,
BufferedImage.TYPE_INT_RGB);
Graphics2D scratchG2 = scratchImage.createGraphics();
scratchG2.setRenderingHints(renderHints);
Font font = new Font("Serif", Font.BOLD | Font.ITALIC, 24);
FontRenderContext frc = scratchG2.getFontRenderContext();
TextLayout tl = new TextLayout(text, font, frc);
Rectangle2D textBounds = tl.getBounds();
int textWidth = (int) Math.ceil(textBounds.getWidth());
int textHeight = (int) Math.ceil(textBounds.getHeight());
int horizontalPad = 600;
int verticalPad = 10;
imageSize = new Dimension(textWidth + horizontalPad, textHeight
+ verticalPad);
image = new BufferedImage(imageSize.width, imageSize.height,
BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = image.createGraphics();
g2.setRenderingHints(renderHints);
int baselineOffset = (verticalPad / 2) - ((int) textBounds.getY());
g2.setColor(Color.BLACK);
g2.fillRect(0, 0, imageSize.width, imageSize.height);
g2.setColor(Color.GREEN);
tl.draw(g2, 0, baselineOffset);
// Free-up resources right away, but keep "image" for
// animation.
scratchG2.dispose();
scratchImage.flush();
g2.dispose();
}
public void paint(Graphics g) {
// Make sure to clip the edges, regardless of curr size
g.setClip(0, 0, imageSize.width, imageSize.height);
int localOffset = currOffset; // in case it changes
g.drawImage(image, -localOffset, 0, this);
g.drawImage(image, imageSize.width - localOffset, 0, this);
// draw outline
g.setColor(Color.black);
g.drawRect(0, 0, imageSize.width - 1, imageSize.height - 1);
}
private void runWork() {
while (noStopRequested) {
try {
Thread.sleep(10); // 10 frames per second
// adjust the scroll position
currOffset = (currOffset + 1) % imageSize.width;
// signal the event thread to call paint()
repaint();
} catch (InterruptedException x) {
Thread.currentThread().interrupt();
}
}
}
public void stopRequest() {
noStopRequested = false;
internalThread.interrupt();
}
public boolean isAlive() {
return internalThread.isAlive();
}
}
回答6:
This is supposed to be an improvement of @camickr MarqueePanel. Please see above.
To map mouse events to the specific components added to MarqueePanel
Override add(Component comp) of MarqueePanel in order to direct all mouse events of the components
An issue here is what do do with the MouseEvents fired from the individual components. My approach is to remove the mouse listeners form the components added and let the MarqueePanel redirect the event to the correct component.
In my case these components are supposed to be links.
@Override
public Component add(Component comp) {
comp = super.add(comp);
if(comp instanceof MouseListener)
comp.removeMouseListener((MouseListener)comp);
comp.addMouseListener(this);
return comp;
}
Then map the component x to a MarqueePanel x and finally the correct component
@Override
public void mouseClicked(MouseEvent e)
{
Component source = (Component)e.getSource();
int x = source.getX() + e.getX();
int y = source.getY();
MarqueePanel2 marqueePanel = (MarqueePanel2) ((JComponent)e.getSource()).getParent();
double x2 = marqueePanel.getWidth();
double x1 = Math.abs(marqueePanel.scrollOffset);
if(x >= x1 && x <= x2)
{
System.out.println("Bang " + x1);
Component componentAt = getComponentAt(x+marqueePanel.scrollOffset, y);
if(comp instanceof MouseListener)
((MouseListener) componentAt).mouseClicked(e);
System.out.println(componentAt.getName());
}
else
{
return;
}
//System.out.println(x);
}
来源：https://stackoverflow.com/questions/3617326/marquee-effect-in-java-swing