How can I make a TextArea stretch to fill the content, expanding the parent in the process?

Question

So I have a TextArea and as the user pastes paragraphs into it, or just writes in it, I want it to expand vertically to reveal all the available text. I.e. not to use a scro

Answer 1

I had a similar problem with creating expanding TextArea. I was creating TextArea that looks like TextField and expand vertically every time when there is no more space in line. I have tested all solutions that I could find on this topic on stack and other sources available. I found few good solutions but neither was good enough.

After many hours of fighting, I figured out this approach.

I extended TextArea class, override layoutChildren() method and add a listener on text height.

  @Override
  protected void layoutChildren() {
    super.layoutChildren();
    setWrapText(true);
    addListenerToTextHeight();
  }

  private void addListenerToTextHeight() {
    ScrollPane scrollPane = (ScrollPane) lookup(".scroll-pane");
    scrollPane.setHbarPolicy(ScrollBarPolicy.NEVER);
    scrollPane.setVbarPolicy(ScrollBarPolicy.NEVER);

    StackPane viewport = (StackPane) scrollPane.lookup(".viewport");

    Region content = (Region) viewport.lookup(".content");

    Text text = (Text) content.lookup(".text");
    text.textProperty().addListener(textHeightListener(text));
  }

  private InvalidationListener textHeightListener(Text text) {
    return (property) -> {
      // + 1 for little margin
      double textHeight = text.getBoundsInLocal().getHeight() + 1;

      //To prevent that our TextArena will be smaller than our TextField
      //I used DEFAULT_HEIGHT = 18.0
      if (textHeight < DEFAULT_HEIGHT) {
        textHeight = DEFAULT_HEIGHT;
      }

      setMinHeight(textHeight);
      setPrefHeight(textHeight);
      setMaxHeight(textHeight);
    };
  }