JavaFX-按钮高度不会变小？

Question

.button
{
    -fx-background-image: url("mapDefault.png");
    -fx-pref-width: 10px;
    -fx-pref-height: 10px;
}

My button looks like this, and theoretically, it should fit the image (10x10) exactly. However

It returns that the button is about 30px in height, despite that I changed it. The button is declared like Button beachButton = new Button(); and does not have any text values in it.

Any possible causes to this increase/min-cap in height?

Answer 1

Any changes in text need to be taken into account, especially custom font. To accommodate for any picture sizes smaller than the font of the item, set the font size equal to 0px as well.

Answer 2

The offset of the icon(or text) from the buttons border may be the problem. A Button with text in default font type & size cannot get smaller in height than 25px (using setPrefHeight() or setStyle(...)). To make the height the same as other controls the padding could be reduced as in the following example:

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.CheckBox;
import javafx.scene.control.Label;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class SmallerButtons  extends Application {
    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage stage) throws Exception {
        Label  label1= new Label ("Label1");
        Label  label2= new Label ("Label2");
        
        CheckBox  checkBox1= new CheckBox ("CheckBox1");
        CheckBox  checkBox2= new CheckBox ("CheckBox2");
        
        Button  button1= new Button ("Button1");
        Button  button2= new Button ("Button2");
        Button  button3= new Button ("Button3");
        
        button3.setOnAction(a-> System.out.println(label1.getHeight() + " / " +checkBox1.getHeight() + " / " +button1.getHeight()));
        
        label1.setStyle("-fx-font-size:10"); 
        button1.setPadding(new Insets(0,3,0,3)); // <----- this one works. Standard value is 5.0.
        button1.setMaxWidth(200);
        button2.setPrefHeight(17); // no effect
        button3.setStyle("-fx-pref-height:35px"); // or also setPrefHeight(35)
        
        VBox vb1=new VBox(label1,label2);
        VBox vb2=new VBox(checkBox1,checkBox2);
        VBox vb3=new VBox(button1, button2, button3);
        vb3.setMaxWidth(80);
        
        vb1.setSpacing(1);
        vb2.setSpacing(1);
        vb3.setSpacing(1);
        HBox hb = new HBox(vb1,vb2,vb3);
        hb.setSpacing(15);
        Scene scene = new Scene(hb);
        stage.setOnCloseRequest((e)->System.exit(0));
        stage.setScene(scene);
        stage.show();
    }   
}

One catch: With one buttons padding adjusted all other buttons need the padding explicitly set, too.