CSS

Syntax#

NodeClass /* selector by Node’s class */
.someclass /* selector by class */
#someId /* selector by id */
[selector1] > [selector2] /* selector for a direct child of a node matching selector1 that matches selector2 */
[selector1] [selector2] /* selector for a descendant of a node matching selector1 that matches selector2 */

Using CSS for styling

CSS can be applied in multiple places:

inline (Node.setStyle)
in a stylesheet
- to a Scene
  - as user agent stylesheet (not demonstrated here)
  - as “normal” stylesheet for the Scene
- to a Node

This allows to change styleable properties of Nodes. The following example demonstrates this:

Application class

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Region;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

public class StyledApplication extends Application {

    @Override
    public void start(Stage primaryStage) {
        
        Region region1 = new Region();
        Region region2 = new Region();
        Region region3 = new Region();
        Region region4 = new Region();
        Region region5 = new Region();
        Region region6 = new Region();
        
        // inline style
        region1.setStyle("-fx-background-color: yellow;");
        
        // set id for styling
        region2.setId("region2");
        
        // add class for styling
        region2.getStyleClass().add("round");
        region3.getStyleClass().add("round");
        
        HBox hBox = new HBox(region3, region4, region5);
        
        VBox vBox = new VBox(region1, hBox, region2, region6);

        Scene scene = new Scene(vBox, 500, 500);
        
        // add stylesheet for root
        scene.getStylesheets().add(getClass().getResource("style.css").toExternalForm());
        
        // add stylesheet for hBox
        hBox.getStylesheets().add(getClass().getResource("inlinestyle.css").toExternalForm());
        
        scene.setFill(Color.BLACK);
        
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }

}

inlinestyle.css

* {
    -fx-opacity: 0.5;
}

HBox {
    -fx-spacing: 10;
}

Region {
    -fx-background-color: white;
}

style.css

Region {
    width: 50;
    height: 70;
    
    -fx-min-width: width;
    -fx-max-width: width;
    
    -fx-min-height: height;
    -fx-max-height: height;
    
    -fx-background-color: red;
}

VBox {
    -fx-spacing: 30;
    -fx-padding: 20;
}

#region2 {
    -fx-background-color: blue;
}

Extending Rectangle adding new stylable properties

The following example demonstrates how to add custom properties that can be styled from css to a custom Node.

Here 2 DoublePropertys are added to the Rectangle class to allow setting the width and height from CSS.

The following CSS could be used for styling the custom node:

 StyleableRectangle {
    -fx-fill: brown;
    -fx-width: 20;
    -fx-height: 25;
    -fx-cursor: hand;
}

Custom Node

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import javafx.beans.property.DoubleProperty;
import javafx.css.CssMetaData;
import javafx.css.SimpleStyleableDoubleProperty;
import javafx.css.StyleConverter;
import javafx.css.Styleable;
import javafx.css.StyleableDoubleProperty;
import javafx.css.StyleableProperty;
import javafx.scene.paint.Paint;
import javafx.scene.shape.Rectangle;

public class StyleableRectangle extends Rectangle {
    
    // declaration of the new properties
    private final StyleableDoubleProperty styleableWidth = new SimpleStyleableDoubleProperty(WIDTH_META_DATA, this, "styleableWidth");
    private final StyleableDoubleProperty styleableHeight = new SimpleStyleableDoubleProperty(HEIGHT_META_DATA, this, "styleableHeight");

    public StyleableRectangle() {
        bind();
    }

    public StyleableRectangle(double width, double height) {
        super(width, height);
        initStyleableSize();
        bind();
    }

    public StyleableRectangle(double width, double height, Paint fill) {
        super(width, height, fill);
        initStyleableSize();
        bind();
    }

    public StyleableRectangle(double x, double y, double width, double height) {
        super(x, y, width, height);
        initStyleableSize();
        bind();
    }
    
    private void initStyleableSize() {
        styleableWidth.set(getWidth());
        styleableHeight.set(getHeight());
    }
    
    private final static List<CssMetaData<? extends Styleable, ?>> CLASS_CSS_META_DATA;
    
    // css metadata for the width property
    // specify property name as -fx-width and
    // use converter for numbers
    private final static CssMetaData<StyleableRectangle, Number> WIDTH_META_DATA = new CssMetaData<StyleableRectangle, Number>("-fx-width", StyleConverter.getSizeConverter()) {

        @Override
        public boolean isSettable(StyleableRectangle styleable) {
            // property can be set iff the property is not bound
            return !styleable.styleableWidth.isBound();
        }

        @Override
        public StyleableProperty<Number> getStyleableProperty(StyleableRectangle styleable) {
            // extract the property from the styleable
            return styleable.styleableWidth;
        }
    };
    
    // css metadata for the height property
    // specify property name as -fx-height and
    // use converter for numbers
    private final static CssMetaData<StyleableRectangle, Number> HEIGHT_META_DATA = new CssMetaData<StyleableRectangle, Number>("-fx-height", StyleConverter.getSizeConverter()) {

        @Override
        public boolean isSettable(StyleableRectangle styleable) {
            return !styleable.styleableHeight.isBound();
        }

        @Override
        public StyleableProperty<Number> getStyleableProperty(StyleableRectangle styleable) {
            return styleable.styleableHeight;
        }
    };
    
    static {
        // combine already available properties in Rectangle with new properties
        List<CssMetaData<? extends Styleable, ?>> parent = Rectangle.getClassCssMetaData();
        List<CssMetaData<? extends Styleable, ?>> additional = Arrays.asList(HEIGHT_META_DATA, WIDTH_META_DATA);

        // create arraylist with suitable capacity
        List<CssMetaData<? extends Styleable, ?>> own = new ArrayList(parent.size()+ additional.size());

        // fill list with old and new metadata
        own.addAll(parent);
        own.addAll(additional);
        
        // make sure the metadata list is not modifiable
        CLASS_CSS_META_DATA = Collections.unmodifiableList(own); 
    }
    
    // make metadata available for extending the class
    public static List<CssMetaData<? extends Styleable, ?>> getClassCssMetaData() {
        return CLASS_CSS_META_DATA;
    }
    
    // returns a list of the css metadata for the stylable properties of the Node
    @Override
    public List<CssMetaData<? extends Styleable, ?>> getCssMetaData() {
        return CLASS_CSS_META_DATA;
    }
    
    private void bind() {
        this.widthProperty().bind(this.styleableWidth);
        this.heightProperty().bind(this.styleableHeight);
    }


    // -------------------------------------------------------------------------
    // ----------------------- PROPERTY METHODS --------------------------------
    // -------------------------------------------------------------------------
    
    public final double getStyleableHeight() {
        return this.styleableHeight.get();
    }

    public final void setStyleableHeight(double value) {
        this.styleableHeight.set(value);
    }

    public final DoubleProperty styleableHeightProperty() {
        return this.styleableHeight;
    }

    public final double getStyleableWidth() {
        return this.styleableWidth.get();
    }

    public final void setStyleableWidth(double value) {
        this.styleableWidth.set(value);
    }

    public final DoubleProperty styleableWidthProperty() {
        return this.styleableWidth;
    }

}