package bluej.utility.javafx;

import java.util.ArrayList;
import java.util.List;
import javafx.animation.Interpolator;
import javafx.animation.KeyFrame;
import javafx.animation.KeyValue;
import javafx.animation.Timeline;
import javafx.beans.binding.DoubleExpression;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.beans.value.ObservableValue;
import javafx.util.Duration;




| A transition that is shared between multiple entities.  For example, you
| may want to animate collapsing all the frames for bird's eye view.  You create
| an instance of this class, pass it to all frames to hook into the progress
| (so that all frames collapse at the same rate), then call animateOver to
| run all the animations together.
|
| This class is used rather than passing a Timeline around, because you can register
| multiple stop listeners to this class more easily.
|
public class SharedTransition
{       
private final List<FXPlatformRunnable> onStopped = new ArrayList<>();
   
   private final DoubleProperty progress = new SimpleDoubleProperty(0.0);
   
   private final DoubleExpression opposite = progress.negate().add(1.0);
   
   private Timeline timeline;
   
   private boolean runStopped;

   
   


| An expression which will animate from 0.0 to 1.0 during the transition
|
public DoubleExpression getProgress()
   {        
      return progress;     
      }

   
   


| An expression which will animate from 1.0 to 0.0 during the transition
|
public DoubleExpression getOppositeProgress()
   {        
      return opposite;     
      }

   
   


| Adds a listener to be execute if the transition finishes naturally,
| or is stopped via the stop() method.
|
public void addOnStopped(FXPlatformRunnable stopped)
   {
      onStopped.add(stopped);     
      }

   
   


| Animates the transition over the given duration.  Should only be called once.
|
public void animateOver(Duration duration)
   {
      if (timeline != null)
       {            
         throw new IllegalStateException("Cannot animate SharedTransition more than one time");         
         }
        
       
      timeline = new Timeline(new KeyFrame(duration, e -> { 
      if (!runStopped)
           {                
         runStopped = true;
         onStopped.forEach(FXPlatformRunnable::run);             
         }         
      }, new KeyValue(progress, 1.0, Interpolator.EASE_BOTH)));
   timeline.play();     
   }
    
   
public void stop()
   {
   if (timeline == null)
       {            
      throw new IllegalStateException("Cannot stop SharedTransition before it is started");         
      }
   timeline.stop();
   progress.set(1.0);
   if (!runStopped)
       {            
      runStopped = true;
      onStopped.forEach(FXPlatformRunnable::run);         
      }     
   } 
}