how to count lines in javafx text area

Question

If text wrapping was set to off, then this would be a trivial matter of course, because lines can be easily counted by counting the number of newline characters. Unfortunately, when text wrapping is on, there does not seem to be any obvious and non-messy way to do this, other than actually putting in newline characters at the end of every row when initializing the box.

Up until now, this is how I solved the problem, however it is highly undesirable since, in many cases, it inserts a newline into the middle of a word, and of course, this solution is convoluted and messy. Does anyone have any suggestions? If I were to wrap my text area inside a textflow container, would there be a way to get around this?

Answer 1

I faced the same problem. After some digging I found this thread which has the answer you are looking for.

It uses a Label to hold the text of the TextArea and updates its height as the Label's height is changed. Here is a complete demo:

import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.GroupBuilder;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.StackPaneBuilder;

public class ScrollFreeTextArea extends StackPane{

     private Label label;
     private StackPane lblContainer ;
     private TextArea textArea;

     private Character NEW_LINE_CHAR = new Character((char)10);
     private final double NEW_LINE_HEIGHT = 18D;
     private final double TOP_PADDING = 3D;
     private final double BOTTOM_PADDING = 6D;

     public ScrollFreeTextArea(){
          super();
          configure();
     }

     public ScrollFreeTextArea(String text){
          super();
          configure();
          textArea.setText(text);
     }

     private void configure(){
          setAlignment(Pos.TOP_LEFT);

          this.textArea =new TextArea();
          this.textArea.setWrapText(true);
          this.textArea.getStyleClass().add("scroll-free-text-area");


          this.label =new Label();
          this.label.setWrapText(true);
          this.label.prefWidthProperty().bind(this.textArea.widthProperty());
          this.label.textProperty().bind(this.textArea.textProperty());

          this.lblContainer = StackPaneBuilder.create()
                                                    .alignment(Pos.TOP_LEFT)
                                                    .padding(new Insets(4,7,7,7))
                                                    .children(label)
                                                    .build();
          // Binding the container width to the TextArea width.
          lblContainer.maxWidthProperty().bind(textArea.widthProperty());

          textArea.textProperty().addListener(new ChangeListener<String>() {
               @Override
               public void changed(ObservableValue<? extends String> paramObservableValue,     String paramT1, String value) {
                    layoutForNewLine(textArea.getText());
               }
          });

          label.heightProperty().addListener(new ChangeListener<Number>() {
               @Override
               public void changed(ObservableValue<? extends Number> paramObservableValue,     Number paramT1, Number paramT2) {
                    layoutForNewLine(textArea.getText());
               }
          });

          getChildren().addAll(GroupBuilder.create().children(lblContainer).build(),textArea);
     }

     private void layoutForNewLine(String text){
          if(text!=null && text.length()>0 && 
                         ((Character)text.charAt(text.length()-1)).equals(NEW_LINE_CHAR)){ 
               textArea.setPrefHeight(label.getHeight() + NEW_LINE_HEIGHT + TOP_PADDING + BOTTOM_PADDING);
               textArea.setMinHeight(label.getHeight() + NEW_LINE_HEIGHT + TOP_PADDING + BOTTOM_PADDING);
          }else{
               textArea.setPrefHeight(label.getHeight() + TOP_PADDING + BOTTOM_PADDING);
               textArea.setMinHeight(label.getHeight() + TOP_PADDING + BOTTOM_PADDING);
          }
     }

}