org.argeo.app.ui/src/org/argeo/app/ui/widgets/DelayedText.java

   1 package org.argeo.app.ui.widgets;
   2
   3 import java.util.ArrayList;
   4 import java.util.List;
   5 import java.util.concurrent.Executors;
   6 import java.util.concurrent.ScheduledExecutorService;
   7 import java.util.concurrent.ScheduledFuture;
   8 import java.util.concurrent.TimeUnit;
   9 import java.util.function.Consumer;
  10
  11 import org.eclipse.rap.rwt.service.ServerPushSession;
  12 import org.eclipse.swt.events.ModifyEvent;
  13 import org.eclipse.swt.events.ModifyListener;
  14 import org.eclipse.swt.widgets.Composite;
  15 import org.eclipse.swt.widgets.Text;
  16
  17 /**
  18  * A text input which notifies changes after a delay, typically in order to
  19  * apply a filter.
  20  */
  21 public class DelayedText {
  22         private final static ScheduledExecutorService scheduler;
  23         static {
  24                 // create only one scheduler, in order not to exhaust threads
  25                 scheduler = Executors.newScheduledThreadPool(0, (r) -> {
  26                         Thread thread = new Thread(r, "Delayed text scheduler");
  27                         // we mark threads as deamons so that the shutdown hook is triggered
  28                         thread.setDaemon(true);
  29                         return thread;
  30                 });
  31                 Runtime.getRuntime().addShutdownHook(new Thread(() -> {
  32                         scheduler.shutdown();
  33                 }, "Shutdown delayed text scheduler"));
  34         }
  35         private final static int DEFAULT_DELAY = 800;
  36
  37         private final long delay;
  38         private final InternalModifyListener modifyListener;
  39         private final Text text;
  40         protected List<Consumer<String>> toDos = new ArrayList<>();
  41         private ServerPushSession pushSession;
  42
  43         private ScheduledFuture<String> lastTask;
  44
  45         public DelayedText(Composite parent, int style) {
  46                 this(parent, style, DEFAULT_DELAY);
  47         }
  48
  49         public DelayedText(Composite parent, int style, long delayInMs) {
  50                 this.delay = delayInMs;
  51                 this.modifyListener = new InternalModifyListener();
  52                 pushSession = new ServerPushSession();
  53                 pushSession.start();
  54                 text = new Text(parent, style);
  55                 text.addModifyListener(modifyListener);
  56         }
  57
  58         protected void notifyText(String txt) {
  59                 // text.getDisplay().syncExec(()-> pushSession.start());
  60                 for (Consumer<String> toDo : toDos) {
  61                         text.getDisplay().syncExec(() -> toDo.accept(txt));
  62                 }
  63                 // text.getDisplay().syncExec(()->pushSession.stop());
  64         }
  65
  66         public Text getText() {
  67                 return text;
  68         }
  69
  70         public void addListener(Consumer<String> toDo) {
  71                 toDos.add(toDo);
  72         }
  73
  74         private class InternalModifyListener implements ModifyListener {
  75                 private static final long serialVersionUID = -6178431173400385005L;
  76
  77                 public void modifyText(ModifyEvent e) {
  78                         String txt = text.getText();
  79                         ScheduledFuture<String> task = scheduler.schedule(() -> {
  80                                 notifyText(txt);
  81                                 return txt;
  82                         }, delay, TimeUnit.MILLISECONDS);
  83                         // cancel previous task
  84                         if (lastTask != null && !lastTask.isDone()) {
  85                                 lastTask.cancel(false);
  86                         }
  87                         lastTask = task;
  88                 }
  89         };
  90
  91 }