JavaFX TextArea - Controlling the scroll bar sizes - javafx

Question

Unpleasantly surprised by TextArea CSS font sizes having wacky effects on the sizes of the scroll bars, I'm trying to get control of the sizes myself. Please refer to the following SSCCE. I can easily control the vertical scroll bar, but the horizontal bar is simply ignoring the sizes I'm setting. Am I expecting something unreasonable here, or is this (yet another) bug in JavaFX? Thanks!
public class Main extends Application {
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage primaryStage) {
TextArea textArea = new TextArea();
int lineCount = 100;
int wordCount = 70;
StringBuilder sb = new StringBuilder();
for (int lineNbr = 0; lineNbr < lineCount; lineNbr++) {
for (int wordNbr = 0; wordNbr < wordCount; wordNbr++) {
sb.append("Sample");
}
sb.append(System.getProperty("line.separator"));
}
textArea.setText(sb.toString());
StackPane root = new StackPane();
root.getChildren().add(textArea);
primaryStage.setScene(new Scene(root, 300, 250));
primaryStage.show();
double prefSize = 50;
ScrollBar vertScrollBar = (ScrollBar)textArea.lookup(".scroll-bar:vertical");
ScrollBar horizScrollBar = (ScrollBar)textArea.lookup(".scroll-bar:horizontal");
vertScrollBar.setPrefWidth(prefSize); // This works great!
horizScrollBar.setPrefHeight(prefSize); // This doesn't do anything!
horizScrollBar.setMinHeight(prefSize); // Nor does this
horizScrollBar.setPrefWidth(prefSize); // Nor this
horizScrollBar.setMinWidth(prefSize); // Nor this
}
}

Answer 1

ScrollBar vertScrollBar = (ScrollBar) textArea.lookup(".scroll-bar:vertical");
ScrollBar horizScrollBar = (ScrollBar) textArea.lookup(".scroll-bar:horizontal");
System.out.println(vertScrollBar + " " + horizScrollBar);
ScrollBar#35ef2d94[styleClass=scroll-bar]
ScrollBar#35ef2d94[styleClass=scroll-bar]
Same object (vertical ScrollBar).
ScrollPane sPane = (ScrollPane)textArea.getChildrenUnmodifiable().get(0);
ScrollBar horizScrollBar = (ScrollBar)sPane.getChildrenUnmodifiable().get(2);
horizScrollBar.setPrefHeight(prefSize); // This does something!
Update: Better way to receive the two ScrollBars.
ScrollBar[] bars = new ScrollBar[2];
textArea.lookupAll(".scroll-bar").toArray(bars);
bars[0].setPrefWidth(prefSize);
bars[1].setPrefHeight(prefSize);
Edit: Explanation for similar problem with lookupAll(...) and pseudo classes here and here.

Answer 2

Lookups are generally pretty fragile (and I don't think they're really intended to be robust); as noted in the links from the other answer they don't appear to support pseudoclasses.
You can of course just use CSS for this:
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.TextArea;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
public class Main extends Application {
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage primaryStage) {
TextArea textArea = new TextArea();
int lineCount = 100;
int wordCount = 70;
StringBuilder sb = new StringBuilder();
for (int lineNbr = 0; lineNbr < lineCount; lineNbr++) {
for (int wordNbr = 0; wordNbr < wordCount; wordNbr++) {
sb.append("Sample");
}
sb.append(System.getProperty("line.separator"));
}
textArea.setText(sb.toString());
StackPane root = new StackPane();
root.getChildren().add(textArea);
Scene scene = new Scene(root, 300, 250) ;
scene.getStylesheets().add("style.css");
primaryStage.setScene(scene);
primaryStage.show();
}
}
with the following in style.css:
.scroll-pane .scroll-bar:horizontal {
-fx-pref-height: 50 ;
}
.scroll-pane .scroll-bar:vertical {
-fx-pref-width: 50 ;
}
This approach, of course, is far more convenient if you have multiple scroll panes in your application and want them all to have the same style of scroll bars.