JavaFX 2按钮大小填充宽度和宽度相同？ [英] JavaFX 2 buttons size fill width and are each same width?

问题描述

使用Java FX 2.2。场景的水平宽度是固定的，但在编译时是未知的。我想在一个完全填充场景中的水平空间的水平行中放置2个或更多按钮，每个按钮的宽度完全相同。按钮数随程序状态动态变化。什么程序片段可以完成这个？

Working in Java FX 2.2. The Scene has a horizontal width that is fixed but is unknown at compile time. I want to place 2 or more buttons in a horizontal row that completely fills the horizontal space in the Scene AND that are each exactly the same width. The number of buttons changes dynamically with the program state. What program snippet will accomplish this?

推荐答案

这段代码来自 HBox javadoc 几乎可以做你想要的，除了按钮本身是不同的大小，基于包含在文本中的文本按钮 - 更宽的文字会导致更宽的按钮。

This code from the HBox javadoc will almost do what you want, except that "buttons themselves are different sizes based on the text contained in the button - wider text causes wider buttons".

HBox hbox = new HBox();
Button button1 = new Button("Add");
Button button2 = new Button("Remove");
HBox.setHgrow(button1, Priority.ALWAYS);
HBox.setHgrow(button2, Priority.ALWAYS);
button1.setMaxWidth(Double.MAX_VALUE);
button2.setMaxWidth(Double.MAX_VALUE);
hbox.getChildren().addAll(button1, button2);

通过创建基于HBox的自定义布局窗格并覆盖它的布局方法，您可以获得完全相同的行为你描述的。

By creating a custom layout pane based on HBox and overriding it's layout method, you can get exactly the behaviour you describe.

import javafx.application.Application;
import javafx.collections.ObservableList;
import javafx.event.*;
import javafx.scene.*;
import javafx.scene.control.Button;
import javafx.scene.layout.*;
import javafx.stage.Stage;

// displays equal width buttons which fill a layout region's width.
// http://stackoverflow.com/questions/12830402/javafx-2-buttons-size-fill-width-and-are-each-same-width
public class HorizontallyTiledButtons extends Application {
  public static void main(String[] args) { launch(args); }
  @Override public void start(Stage stage) {
    final Button addButton    = new Button("Add");
    final Button removeButton = new Button("Remove");
    final Button extraButton  = new Button("The wizard of Frobozz is watching");

    final ButtonBar buttonBar = new ButtonBar(5, addButton, removeButton);

    addButton.setOnAction(new EventHandler<ActionEvent>() {
      @Override public void handle(ActionEvent event) {
        buttonBar.addButton(extraButton);
      }
    });

    removeButton.setOnAction(new EventHandler<ActionEvent>() {
      @Override public void handle(ActionEvent event) {
        buttonBar.removeButton(extraButton);
      }
    });

    VBox layout = new VBox(10);
    layout.getChildren().addAll(buttonBar);
    layout.setStyle("-fx-background-color: cornsilk; -fx-padding: 10;");

    stage.setScene(new Scene(layout));
    stage.setWidth(800);
    stage.show();
  }

  class ButtonBar extends HBox {
    ButtonBar(double spacing, Button... buttons) {
      super(spacing);
      getChildren().addAll(buttons);
      for (Button b: buttons) {
        HBox.setHgrow(b, Priority.ALWAYS);
        b.setMaxWidth(Double.MAX_VALUE);
      }
    }

    public void addButton(Button button) {
      HBox.setHgrow(button, Priority.ALWAYS);
      button.setMaxWidth(Double.MAX_VALUE);
      ObservableList<Node> buttons = getChildren();
      if (!buttons.contains(button)) {
        buttons.add(button);
      }
    }

    public void removeButton(Button button) {
      getChildren().remove(button);
    }

    @Override protected void layoutChildren() {
      double minPrefWidth = calculatePrefChildWidth();
      for (Node n: getChildren()) {
        if (n instanceof Button) {
          ((Button) n).setMinWidth(minPrefWidth);
        }
      }
      super.layoutChildren();
    }

    private double calculatePrefChildWidth() {
      double minPrefWidth = 0;
      for (Node n: getChildren()) {
        minPrefWidth = Math.max(minPrefWidth, n.prefWidth(-1));
      }
      return minPrefWidth;
    }
  }
}

示例程序输出：

Sample program output:

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