JavaFX:如何检测是否按住了某个键? [英] JavaFX : How to detect if a key is being held down?

问题描述

我正在使用Timelines，希望将一些KeyPress事件挂接到舞台上，这可能会改变时间轴在其运行过程中更改属性的方式.

I'm working with Timelines and was hoping to hook up some KeyPress events to the stage that could alter the way the timeline changes the properties over the course it runs.

我知道如何区分按下的按键和想要听的按键，但是需要知道如何确定按键是否刚刚被按下(例如键入)或是否被按下保持更长的时间，以便我可以在按住键的时间越长时使程序进行更快的调整.

I know how to differentiate between what key was pressed and for what keys I want to listen, but need to know how I can determine if a key has just been pressed once, like typing, or if a key is being held down for a longer period of time, so that I can have the program make more rapid adjustments the longer the key is held down.

推荐答案

按住某个键时，您会不断收到KEY_PRESSED事件.您可以计算连续按下同一键的次数:

When a key is being held down, you keep on getting KEY_PRESSED events. You can count how many presses of the same key you get in a row:

SimpleIntegerProperty aCount = new SimpleIntegerProperty(0);
SimpleIntegerProperty bCount = new SimpleIntegerProperty(0);

KeyCombination a = new KeyCodeCombination(KeyCode.A);
KeyCombination b = new KeyCodeCombination(KeyCode.B);

scene.setOnKeyPressed(ke -> {
    aCount.set(a.match(ke) ? aCount.get() + 1 : 0);
    bCount.set(b.match(ke) ? bCount.get() + 1 : 0);
});
scene.setOnKeyReleased(ke -> {
    if(a.match(ke)) { aCount.set(0); }
    else if(b.match(ke)) { bCount.set(0); }
});

这是一个简单的测试应用程序:

Here is a simple test application:

import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyCodeCombination;
import javafx.scene.input.KeyCombination;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;

public class KeySpeedTest extends Application {

    @Override
    public void start(Stage primaryStage) {
        SimpleIntegerProperty aCount = new SimpleIntegerProperty(0);
        SimpleIntegerProperty bCount = new SimpleIntegerProperty(0);

        KeyCombination a = new KeyCodeCombination(KeyCode.A);
        KeyCombination b = new KeyCodeCombination(KeyCode.B);

        Label aLabel = new Label();
        Label bLabel = new Label();
        aLabel.textProperty().bind(Bindings.concat("  A:  ", aCount));
        bLabel.textProperty().bind(Bindings.concat("  B:  ", bCount));

        HBox root = new HBox(aLabel, bLabel);
        Scene scene = new Scene(root, 300, 250);

        scene.setOnKeyPressed(ke -> {
            aCount.set(a.match(ke) ? aCount.get() + 1 : 0);
            bCount.set(b.match(ke) ? bCount.get() + 1 : 0);
        });
        scene.setOnKeyReleased(ke -> {
            if(a.match(ke)) { aCount.set(0); }
            else if(b.match(ke)) { bCount.set(0); }
        });

        primaryStage.setScene(scene);
        primaryStage.setTitle("Key Speed Test");
        primaryStage.show();
    }

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

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