au.com.southsky.jfreesane

Class RateLimitingScanListeners

java.lang.Object

au.com.southsky.jfreesane.RateLimitingScanListeners

public final class RateLimitingScanListeners
extends java.lang.Object

A static factory of listeners that limit the rate at which they send ScanListener.recordRead(au.com.southsky.jfreesane.SaneDevice, int, int) notifications. The primary purpose of this class is to allow users to easily build user interfaces that provide progress information without having to deal with these potentially very high frequency notifications.

For example:

   final JProgressBar progressBar = new JProgressBar();
   // Construct a new ScanAdapter that updates progressBar.
   ScanListener progressBarUpdater = new ScanAdapter() {
      @Override public recordRead(...) {
       // Swing updates must be done in the Swing event listener thread.
       SwingUtilities.invokeLater(new Runnable() {
          @Override public void run() {
           progressBar.setValue(...);
         }
       });
     }
   };

   // Wrap the listener to yield notifications up to 10 times per second and acquire the image.
   ScanListener rateLimitedListener = RateLimitingScanListeners
       .noMoreFrequentlyThan(progressBarUpdater, 100, TimeUnit.MILLISECONDS));
   saneDevice.acquireImage(rateLimitedListener);
 

Method Summary

Modifier and Type	Method and Description
static ScanListener	noMoreFrequentlyThan(ScanListener listener, long time, java.util.concurrent.TimeUnit timeUnit) Returns ScanListener that calls the given listener ScanListener.recordRead(au.com.southsky.jfreesane.SaneDevice, int, int) method no more frequently than the given time any one device.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

noMoreFrequentlyThan

public static ScanListener noMoreFrequentlyThan(ScanListener listener,
                                                long time,
                                                java.util.concurrent.TimeUnit timeUnit)

Returns ScanListener that calls the given listener ScanListener.recordRead(au.com.southsky.jfreesane.SaneDevice, int, int) method no more frequently than the given time any one device. Record read events from one device that occur more frequently are simply discarded.