JavaFX密钥中断？ [英] JavaFX key interruptions?

问题描述

我正在尝试用JavaFX编写一个游戏，但我遇到了一个小问题，那就是关键的听众被其他按键打断了。我正在使用 scene.setOnKeyPressed（KeyEvent）并且它可以工作。当玩家按下一个键时，他们会持续移动，但如果他们按下另一个键，即使他们放开了第二个键，也会忘记第一个键。我正在试图弄清楚如何允许他们做一个动作然后当他们持有的钥匙被释放时，如果他们仍然持有另一个回到那个。

I'm trying to write a game in JavaFX but I'm having a slight issue with it and that's the key listeners getting interrupted by other key presses. I'm using scene.setOnKeyPressed(KeyEvent) and it works. When the player holds down a key they move continuously but if they hit another key it forgets about the first key even if they let go of the second key. I'm trying to figure out how to allow them to do one action and then when the key they were holding is released if they're still holding the other one go back to that.

推荐答案

这类似于这个问题，虽然要求看起来略有不同。类似的技术可以工作，但是如果你只想回应最近按下的键，你可能需要某种堆栈。

This is similar to this question, though the requirements look slightly different. Similar techniques work, but if you just want to respond to the most-recently-pressed key, you probably need some kind of stack.

此示例允许您使用向上，向下，向左或向右光标键在屏幕上移动矩形;仅使用仍处于关闭状态的最近按下的键。

This example allows you to move a rectangle around the screen, with the up, down, left, or right cursor keys; only the most recently pressed key that is still down is used.

import java.util.LinkedList;

import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.beans.property.LongProperty;
import javafx.beans.property.SimpleLongProperty;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class KeyStackExample extends Application {

    @Override
    public void start(Stage primaryStage) {
        Rectangle rect = new Rectangle(50, 50, 100, 50);
        rect.setFill(Color.SALMON);

        Pane pane = new Pane(rect);
        Scene scene = new Scene(pane, 800, 600);

        final double rectangleHSpeed = 100 ; // pixels per second
        final double rectangleVSpeed = 100 ;
        final double minX = 0 ;
        final double maxX = 800 ; 
        final double minY = 0 ;
        final double maxY = 600 ;

        final LinkedList<KeyCode> keyStack = new LinkedList<>();
        scene.setOnKeyPressed(event -> {
            KeyCode code = event.getCode();
            if (! keyStack.contains(code)) {
                keyStack.push(code); 
            }
        });

        scene.setOnKeyReleased(event -> 
            keyStack.remove(event.getCode()));


        final LongProperty lastUpdateTime = new SimpleLongProperty();
        final AnimationTimer rectangleAnimation = new AnimationTimer() {
          @Override
          public void handle(long timestamp) {
            if (! keyStack.isEmpty() && lastUpdateTime.get() > 0) {
              final double elapsedSeconds = (timestamp - lastUpdateTime.get()) / 1_000_000_000.0 ;
              double deltaX = 0 ;
              double deltaY = 0 ;
              switch(keyStack.peek()) {
              case UP:
                  deltaY = -rectangleVSpeed * elapsedSeconds;
                  break ;
              case DOWN: 
                  deltaY = rectangleVSpeed * elapsedSeconds ;
                  break ;
              case LEFT:
                  deltaX = -rectangleHSpeed * elapsedSeconds ;
                  break ;
              case RIGHT:
                  deltaX = rectangleHSpeed * elapsedSeconds ;
              default:
                  break ;
              }
              double oldX = rect.getTranslateX() ;
              double oldY = rect.getTranslateY() ;
              rect.setTranslateX(clamp(oldX + deltaX, minX, maxX));
              rect.setTranslateY(clamp(oldY + deltaY, minY, maxY));
            }
            lastUpdateTime.set(timestamp);
          }
        };
        rectangleAnimation.start();

        primaryStage.setScene(scene);
        primaryStage.show();
    }

    private double clamp(double value, double min, double max) {
        return Math.max(min, Math.min(max, value));
    }

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

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