JavaFX Canvas无法接收关键事件 [英] JavaFX Canvas not picking up key events

问题描述

我有以下代码显示了具有3个连续的hello世界的JavaFX Canvas

I have the following code showing a JavaFX Canvas with 3 consecutive hello worlds

    StackPane root = new StackPane();

        Canvas canvas = new Canvas(250,250);
        canvas.setOnMouseEntered((a) -> System.out.println("hi"));
        canvas.setOnMousePressed((a) -> System.out.println("focus"));
        canvas.setOnKeyReleased(new EventHandler<KeyEvent>() {

            @Override
            public void handle(KeyEvent event) {
                System.out.println("Handled");
            }
        });
//        canvas.setOnKeyPressed((a) -> System.out.println("hi"));

        GraphicsContext context = canvas.getGraphicsContext2D();
        context.setFill(Color.BLUE);
        final int fontSize = 15, fontSpace = 5;
        context.setFont(Font.font(15));

        context.fillText("hello world", 75, 75);
        context.fillText("hello world", 75, 75 + fontSize + fontSpace);
        context.fillText("hello world", 75, 75 + (fontSize + fontSpace) * 2);

        root.getChildren().add(canvas);

        Scene scene = new Scene(root, 300, 250);

        primaryStage.setTitle("Hello World!");
        primaryStage.setScene(scene);
        primaryStage.show();

当我将鼠标悬停在它上面时，它会显示"hi".当我单击它时，它会打印焦点".当我按下键时，什么也没发生.有什么我想念的吗?

When I mouse over it, it prints "hi". When I click it, it prints "focus". When i press keys, nothing happens. Is there something I'm missing?

推荐答案

您需要

canvas.setFocusTraversable(true);

因为画布没有 focusTraversable 默认设置.

as canvases do not have focusTraversable set by default.

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