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JavaFX autoscroll down scroll

Is there a way for the ScrollPane to automatically scroll as its content height increases? For example, I have a TitledPane at the bottom of the screen (inside a ScrollPane) and when I expand it, I would like the ScrollPane to scroll down so I can see all the content of the TitledPane.

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5 answers


You can achieve this behavior. With a combination titledPane.localToScene()

andscrollPane.setVvalue()



The first is to get the coordinates of the titledPane, and the second is to set the position of the vertical scrollbar. Note that it ranges from 0 to 1.

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You can bind

property ScrollPane

vvalue

from an heightProperty

inner container. For example, if you have VBox

in ScrollPane

:



scrollPane.vvalueProperty().bind(vBox.heightProperty());
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You must tell the scrollpane where the current coordinates are before passing the value to the vertical or horizontal bar.

This code works really well for me:

// the owner node of your scrollPane;
titledPane.layout(); 
// the maxValue for scrollPane bar ( 1.0 it the default value )
scrollPane.setVvalue( 1.0d );

You need to code this when your scrollpane grows. For example, if you are adding nodes to an internal scrollpane node, add a list of listeners to it.

If the inner scroll node changes its height, add a listener to heightProperty.

For example, the inner node of your scrollPane is an AnchorPane and you are adding nodes to that panel, so follow these steps:

anchorPane.getChildren().addListener( 
    ( ListChangeListener.Change<? extends Node> c ) -> {
        titledPane.layout();
        scrollPane.setVvalue( 1.0d ); 
    }
);

If it is a height that grows ...

heightProperty().addListener(
    (observable, oldValue, newValue) -> {
        titledPane.layout();
        scrollPane.setVvalue( 1.0d ); 
    }
);

What is it!

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You can add a listener to the TitledPane's height property like this:

titledPane.heightProperty().addListener((observable, oldValue, newValue) -> 
       vvalueProperty().set(newValue.doubleValue()));
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I did it using AnimationTimer. I had to wait 100,000,000 nanoseconds to make sure the ScrollPane responded to the extended Titlepane.

public void scrollNodeInTopScrollPane(Node n, ScrollPane s) {
    final Node node = n;
    final ScrollPane clientTopScrollPane = s;
    AnimationTimer timer = new AnimationTimer() {
        long lng = 0;
        @Override
        public void handle(long l) {
            if (lng == 0) {
                lng = l;                   
            }                
            if (l > lng + 100000000) {                   
                if (node.getLocalToSceneTransform().getTy() > 20) {                      
                    clientTopScrollPane.setVvalue(clientTopScrollPane.getVvalue() + 0.05);                        
                    if (clientTopScrollPane.getVvalue() == 1) {
                        this.stop();                          
                    }
                } else {
                    this.stop();
                }
            }                
        }
    };
    timer.start();
}
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