使用JavaFX 2.2助记符(和加速器)

Question

我正在努力使JavaFX Mnemonic工作.我在场景上有一些按钮,我想要实现的是按Ctrl + S来触发此按钮事件.这是一个代码方案:

@FXML
public Button btnFirst;

btnFirst.getScene().addMnemonic(new Mnemonic(btnFirst, 
            new KeyCodeCombination(KeyCode.S, KeyCombination.CONTROL_DOWN)));

Button的mnemonicParsing是错误的.(好吧,在尝试完成这项工作时,我试图将其设置为true,但没有结果).JavaFX文档指出,当在场景上注册助记符,并且KeyCombination到达未使用的场景时,目标节点将被发送一个ActionEvent.但这不起作用,可能,我做错了......

我可以使用标准按钮的助记符(通过将mnemonicParsing设置为true并使用下划线字符设置前缀'F'字母).但是这样用户必须使用Alt键,这会在带有菜单栏的浏览器上带来一些奇怪的行为(如果应用程序嵌入到网页中,而不是通过按Alt + S触发按钮事件后激活的浏览器菜单).此外,标准方式使得无法像Ctrl + Shift + F3等那样制作快捷方式.

那么,如果有某种方法可以使这项工作？

Answer 1

对于您的用例,我认为您实际上想要使用加速器而不是助记符.

button.getScene().getAccelerators().put(
  new KeyCodeCombination(KeyCode.S, KeyCombination.SHORTCUT_DOWN), 
  new Runnable() {
    @Override public void run() {
      button.fire();
    }
  }
);

在大多数情况下,建议您使用KeyCombination.SHORTCUT_DOWN作为修饰符说明符,如上面的代码所示.KeyCombination文档中有一个很好的解释:

快捷键修饰符用于表示主机平台上键盘快捷键中常用的修饰键.这是例如Windows上的控件和Mac上的元(命令键).通过使用快捷键修饰符,开发人员可以创建独立于平台的快捷方式.因此,"Shortcut + C"组合键在Windows内部处理为"Ctrl + C",在Mac上处理为"Meta + C".

如果你想专门编写只处理Ctrl + S组合键的代码,你可以使用它们:

new KeyCodeCombination(KeyCode.S, KeyCombination.CONTROL_DOWN)

这是一个可执行的例子:

import javafx.animation.*;
import javafx.application.Application;
import javafx.event.*;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.image.*;
import javafx.scene.input.*;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.util.Duration;

public class SaveMe extends Application {
  @Override public void start(final Stage stage) throws Exception {
    final Label response = new Label();
    final ImageView imageView = new ImageView(
      new Image("http://icons.iconarchive.com/icons/gianni-polito/colobrush/128/software-emule-icon.png")
    );
    final Button button = new Button("Save Me", imageView);
    button.setStyle("-fx-base: burlywood;");
    button.setContentDisplay(ContentDisplay.TOP);
    displayFlashMessageOnAction(button, response, "You have been saved!");

    layoutScene(button, response, stage);
    stage.show();

    setSaveAccelerator(button);
  }

  // sets the save accelerator for a button to the Ctrl+S key combination.
  private void setSaveAccelerator(final Button button) {
    Scene scene = button.getScene();
    if (scene == null) {
      throw new IllegalArgumentException("setSaveAccelerator must be called when a button is attached to a scene");
    }

    scene.getAccelerators().put(
      new KeyCodeCombination(KeyCode.S, KeyCombination.SHORTCUT_DOWN), 
      new Runnable() {
        @Override public void run() {
          fireButton(button);
        }
      }
    );
  }

  // fires a button from code, providing visual feedback that the button is firing.
  private void fireButton(final Button button) {
    button.arm();
    PauseTransition pt = new PauseTransition(Duration.millis(300));
    pt.setOnFinished(new EventHandler<ActionEvent>() {
      @Override public void handle(ActionEvent event) {
        button.fire();
        button.disarm();
      }
    });
    pt.play();
  }

  // displays a temporary message in a label when a button is pressed, 
  // and gradually fades the label away after the message has been displayed.
  private void displayFlashMessageOnAction(final Button button, final Label label, final String message) {
    final FadeTransition ft = new FadeTransition(Duration.seconds(3), label);
    ft.setInterpolator(Interpolator.EASE_BOTH);
    ft.setFromValue(1);
    ft.setToValue(0);
    button.setOnAction(new EventHandler<ActionEvent>() {
      @Override public void handle(ActionEvent event) {
        label.setText(message);
        label.setStyle("-fx-text-fill: forestgreen;");
        ft.playFromStart();
      }
    });
  }

  private void layoutScene(final Button button, final Label response, final Stage stage) {
    final VBox layout = new VBox(10);
    layout.setPrefWidth(300);
    layout.setAlignment(Pos.CENTER);
    layout.getChildren().addAll(button, response);
    layout.setStyle("-fx-background-color: cornsilk; -fx-padding: 20; -fx-font-size: 20;");
    stage.setScene(new Scene(layout));
  }

  public static void main(String[] args) { launch(args); }
}
// icon license: (creative commons with attribution) http://creativecommons.org/licenses/by-nc-nd/3.0/
// icon artist attribution page: (eponas-deeway) http://eponas-deeway.deviantart.com/gallery/#/d1s7uih

样本输出: