I'm using JavaFX's built-in Dialog extensively in our application. Additionally, all my dialogs and general UI scenes are dynamically wrapped and scaled using a custom utility called LetterBoxer.java (related question).
The utility places UI components into a StackPane, centers them, and scales them dynamically based on scene/window resizing.
When displaying dialogs with varying title lengths, each Dialog header automatically adjusts its width, causing visual inconsistency from one dialog to another.
package dynamicDialogFixedWidthExample;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.AnchorPane;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
public class DynamicDialogFixedWidthExample extends Application {
@Override
public void start(Stage primaryStage) {
Label headerLabel = new Label("An Extremely Long Header Title for Testing");
headerLabel.setStyle("-fx-font-size: 16px; -fx-background-color: lightblue; -fx-padding: 10;");
headerLabel.setWrapText(true);
BorderPane borderPane = getBorderPane(headerLabel);
AnchorPane rootAnchorPane = new AnchorPane(borderPane);
AnchorPane.setTopAnchor(borderPane, 0.0);
AnchorPane.setBottomAnchor(borderPane, 0.0);
AnchorPane.setLeftAnchor(borderPane, 0.0);
AnchorPane.setRightAnchor(borderPane, 0.0);
LetterBoxer letterBoxer = new LetterBoxer();
Scene scene = letterBoxer.box(rootAnchorPane);
primaryStage.setScene(scene);
scene.setOnMouseClicked(event -> {
if (headerLabel.getText().equals("An Extremely Long Header Title for Testing")) {
headerLabel.setText("Short");
} else if (headerLabel.getText().equals("Short")) {
headerLabel.setText("This is a Title");
} else {
headerLabel.setText("An Extremely Long Header Title for Testing");
}
});
primaryStage.setTitle("Dynamic Width Dialog Example");
primaryStage.setWidth(250);
primaryStage.setHeight(250);
primaryStage.show();
}
private static BorderPane getBorderPane(Label headerLabel) {
Label centerContent = new Label("Centered Content Goes Here");
centerContent.setStyle("-fx-font-size: 14px; -fx-background-color: lightgray; -fx-padding: 20;");
Label footerLabel = new Label("Footer");
footerLabel.setStyle("-fx-font-size: 14px; -fx-background-color: lightgreen; -fx-padding: 10;");
BorderPane borderPane = new BorderPane();
borderPane.setTop(headerLabel);
borderPane.setCenter(centerContent);
borderPane.setBottom(footerLabel);
return borderPane;
}
public static void main(String[] args) {
launch(args);
}
}
LetterBoxer.java
package dynamicDialogFixedWidthExample;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.geometry.Bounds;
import javafx.scene.Group;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.layout.StackPane;
import javafx.scene.transform.Scale;
public class LetterBoxer {
public Scene box(final Parent content) {
return box(content, 1);
}
public Scene box(final Parent content, final double minScale) {
// the content is wrapped in a Group so that the stack centers
// the scaled node rather than the untransformed node.
Group group = new Group(content);
Scene scene = new Scene(group);
// generate a layout pass.
group.applyCss();
group.layout();
// determine the default ratio of laid out components.
final Bounds layoutBounds = group.getLayoutBounds();
final double initWidth = layoutBounds.getWidth();
final double initHeight = layoutBounds.getHeight();
final double ratio = initWidth / initHeight;
StackPane stackPane = new StackPane(group);
// place the root in a stack to keep it centered.
scene.setRoot(
stackPane
);
// configure a listener to adjust the size of the scene content (by scaling it).
BoxParams boxParams = new BoxParams(
scene, minScale, ratio, initHeight, initWidth, content
);
// adjust the size of the scene content (by scaling it) if the size changes.
BoxSizeAdjuster boxSizeAdjuster = new BoxSizeAdjuster(boxParams);
scene.widthProperty().addListener(boxSizeAdjuster);
scene.heightProperty().addListener(boxSizeAdjuster);
return scene;
}
private record BoxParams(
Scene scene,
double minScale,
double ratio,
double initHeight, double initWidth,
Parent content
) {
}
private static class BoxSizeAdjuster
implements ChangeListener<Number> {
private final BoxParams boxParams;
private final Scale scale = new Scale();
public BoxSizeAdjuster(BoxParams boxParams) {
this.boxParams = boxParams;
scale.setPivotX(0);
scale.setPivotY(0);
boxParams.content.getTransforms().setAll(scale);
}
@Override
public void changed(
ObservableValue<? extends Number> observableValue,
Number oldValue,
Number newValue
) {
final double newWidth = boxParams.scene.getWidth();
final double newHeight = boxParams.scene.getHeight();
final double scaleFactor =
Math.max(
newWidth / newHeight > boxParams.ratio
? newHeight / boxParams.initHeight
: newWidth / boxParams.initWidth,
boxParams.minScale
);
scale.setX(scaleFactor);
scale.setY(scaleFactor);
}
}
}
Due to varying title lengths, the header width fluctuates noticeably.
They didn't provide consistent dynamic adaptability considering the custom StackPane scaling wrapper.
How can I consistently enforce a stable header width in JavaFX dialogs within dynamic scaling environments created by StackPane wrapping?
Any guidance or effective techniques for managing dynamic layout sizing in wrapped JavaFX UIs would be greatly appreciated.
Thanks everyone for the feedback—I’ve significantly clarified the question, added context around the scaling wrapper (LetterBoxer), and provided a minimal reproducible example. I'd appreciate if you could take another look!
Problem:
When using JavaFX’s Dialog class, the dialog width was changing dynamically based on the header text length, leading to inconsistent widths across different dialogs.
Cause:
JavaFX automatically adjusts the preferred size of a Label inside a DialogPane based on content length.
If the header text is short, the dialog shrinks.
If the header text is long, the dialog expands.
Without constraints, JavaFX does not wrap text correctly inside a DialogPane, which further contributes to unpredictable behavior.
Solution:
To enforce a consistent width while still allowing text to wrap properly, add this line:
headerLabel.setPrefWidth(250);
under the line
headerLabel.setWrapText(true);
✅ setWrapText(true); ensures long text doesn’t force the dialog to grow indefinitely.
✅ setPrefWidth(250); ensures the label stays at a consistent width instead of dynamically resizing.
Why This Works:
JavaFX doesn’t automatically wrap text in Label unless setWrapText(true); is set.
Without setPrefWidth(), the Label does not know when to wrap and just expands.
This fix works within JavaFX’s intended API behavior rather than trying to override it.
Thanks to this simple fix, my dialogs now maintain a consistent width, while still allowing longer titles to wrap properly instead of expanding the dialog size.
Additional Reference:
This answer was inspired by this discussion on javaFx Label wrapText doesn't work.