如何通过JavaFX而不是FXML CSS修改MenuButton箭头颜色？

Question

i am trying to modify color of MenuButton arrow , using JavaFX code not by CSS .

i found it inside caspian.css :

.menu-button > .arrow-button > .arrow {
    -fx-background-insets: 1 0 -1 0, 0;
    -fx-background-color: -fx-mark-highlight-color, -fx-mark-color;
    -fx-padding: 0.25em; /* 3 */
    -fx-shape: "M 0 -3.5 v 7 l 4 -3.5 z";
}

i tried to use something like that :

menubutton.lookup(".arrow");

but it throw NullPointerException

and when i do that :

System.out.println(this.getStyleClass().toString());

it out put that only: menu-button only.

so can any one give me the way to modify it using Java without using CSS ??

Answer 1

This works:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.MenuButton;
import javafx.scene.control.MenuItem;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class RedMenuButton extends Application {

    @Override
    public void start(Stage primaryStage) {
        final StackPane root = new StackPane();
        final MenuButton menuButton = new MenuButton("Menu");
        menuButton.getItems().addAll(new MenuItem("Item 1"), new MenuItem("Item 2"), new MenuItem("Item 3"));
        root.getChildren().add(menuButton);

        final Scene scene = new Scene(root, 250, 150);
        primaryStage.setScene(scene);
        primaryStage.show();

        menuButton.lookup(".arrow").setStyle("-fx-background-color: red;");
    }

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

Update: But this is a better solution (which I probably would have got first time if daylight savings hadn't messed with my sleep ;)).

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.MenuButton;
import javafx.scene.control.MenuItem;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class RedMenuButton extends Application {

    @Override
    public void start(Stage primaryStage) {
        final StackPane root = new StackPane();
        final MenuButton menuButton = new MenuButton("Menu");
        menuButton.getItems().addAll(new MenuItem("Item 1"), new MenuItem("Item 2"), new MenuItem("Item 3"));
        root.getChildren().add(menuButton);

        menuButton.setStyle("-fx-mark-color: red");

        final Scene scene = new Scene(root, 250, 150);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

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

Answer 2

There are several ways to do this, here are four. The code is Jython with JavaFX. You can edit this code to meet your needs.

---

First, the enum, for context.

public enum URLBarArrowConstants {
     //URLBarArrow Constants
     BYCSS_AND_SHAPE,
     BYCSS_AND_NO_SHAPE,
     NOCSS_AND_SHAPE,
     NOCSS_AND_NO_SHAPE;
}

Second, the css files, for context.

EG #1

/*ComboBox's Arrow is a Region.*/
.combo-box .arrow-button .arrow {
     -fx-shape: "...";
     -fx-scale-shape: true;
     -fx-position-shape: true;
}

EG#2

/*ComboBox's Arrow is a Region.*/
.combo-box .arrow-button .arrow {
    /*Setting either of these two will do.*/
     -fx-background-color: transparent; 
     -fx-opacity: 0.0;  
}

/*ComboBox's Arrow Button is a Stack Pane.*/
.combo-box .arrow-button{
    -fx-background-position: center;
    -fx-background-repeat: no-repeat;
    -fx-background-image: url("..<file>.png");
}

---

The method, in my main file.

def setCustomURLBarArrow(self, url_bar, scene, URLBarArrowConstant):
    from javafx.scene.paint import Paint
    from javafx.scene.shape import Shape, SVGPath, FillRule

Don't configure the ComboBox Arrow by CSS, instead, do it programmatically and change the Regions SVG Shape

if URLBarArrowConstant == URLBarArrowConstants.NOCSS_AND_SHAPE:

    #SVG Object
    previous_url_bar = SVGPath()

    #SVG Path
    previous_url_bar.setContent("...") # edit this 

    #SVG Fill Rule
    previous_url_bar.setFillRule(FillRule.NON_ZERO)

    #Set Fill -- 
    previous_url_bar.setFill(Paint.valueOf(Color.web("...").toString())) //edit here

    #Apply CSS Sheet
    url_bar.applyCss()

    #Set Region's Shape
    arrow_region = url_bar.lookup(".arrow").setShape(previous_url_bar)

Configure the ComboBox Arrow by CSS and change the Regions SVG Shape

elif URLBarArrowConstant == URLBarArrowConstants.BYCSS_AND_SHAPE:
    #Apply Stylesheet for URL Bar
    scene.getStylesheets().add(File("..<file>.css").toURI().toString()) //edit here

Configure the ComboBox Arrow by CSS but instead, merely hide the arrow by setting the transparency/opacity values and set a background.

elif URLBarArrowConstant == URLBarArrowConstants.BYCSS_AND_NO_SHAPE:
    #Apply Stylesheet for URL Bar
    scene.getStylesheets().add(File("..<file>.css").toURI().toString()) //edit here

Don't configure the ComboBox Arrow by CSS, instead, do it programmatically and merely hide the arrow by setting the transparency/opacity values and set a background.

elif URLBarArrowConstant == URLBarArrowConstants.NOCSS_AND_NO_SHAPE:

    from javafx.scene.paint import Paint
    from javafx.scene.layout import CornerRadii
    from javafx.scene.layout import Background, BackgroundSize, BackgroundImage, BackgroundPosition, BackgroundRepeat, BackgroundFill

    #Apply CSS Sheet
    url_bar.applyCss()

    #Grab Arrow(Region), ArrowButton(StackPane) ComboBox properties
    arrow_region = url_bar.lookup(".arrow")
    arrow_button = url_bar.lookup(".arrow-button")

    #Either Set Opacity to 0 or set background color to transparent.
    arrow_region.setOpacity(0.0)
    arrow_region.setBackground( Background( array(BackgroundFill, [BackgroundFill( Paint.valueOf(Color.TRANSPARENT.toString()), CornerRadii.EMPTY, Insets.EMPTY)]) ) )

    #Set a Background Image for the .arrow-button StackPane.
    arrow_button.setBackground(Background( array(BackgroundImage, [BackgroundImage( Image( String(File('..<file>.png').toURI().toString()), True) , BackgroundRepeat.NO_REPEAT, BackgroundRepeat.NO_REPEAT, BackgroundPosition.CENTER, BackgroundSize.DEFAULT)] ) ) )       //if you want, edit this