JavaFX 路径转换在 n 秒内播放并暂停答案

【问题标题】：JavaFX Path Transition play during n seconds and pauseJavaFX 路径转换在 n 秒内播放并暂停
【发布时间】：2018-01-17 20:01:43
【问题描述】：

我正在使用 JavaFX 做一个应用程序，但我遇到了问题。

我有一个跟随路径的动画，但我需要在 n 秒后暂停动画并在其他 n 秒后从之前的位置继续。

代码：

public class Controller {

    @FXML
    ImageView img1;

    @FXML
    private Path road;        

    private PathTransition anim;

    public void initialize() {

        road.setStroke(Color.WHITE);
        road.setStrokeWidth(4);
        road.getStrokeDashArray().addAll(10.0, 10.0);

        // Car 1
        img1.setImage(new Image("file:src/vehicle1.png"));
        img1.setX(-img1.getImage().getWidth() / 2);
        img1.setY(300 - img1.getImage().getHeight());
        img1.setRotate(0);
        img1.setFitHeight(0);
        img1.setFitWidth(0);

    }   

    public void startRace() {

        anim = new PathTransition();
        anim.setNode(img1);
        anim.setPath(road);
        anim.setOrientation(PathTransition.OrientationType.ORTHOGONAL_TO_TANGENT);
        anim.setInterpolator(Interpolator.LINEAR);
        anim.setDuration(new Duration(6000));
        //anim.setCycleCount(Timeline.INDEFINITE);

        anim.play();

    }
}

谢谢。

【问题讨论】：

标签： java animation javafx

【解决方案1】：

使用Timeline，控制何时播放和暂停动画。

Timeline playtime = new Timeline(
    new KeyFrame(Duration.seconds(0), event -> anim.play()),
    new KeyFrame(Duration.seconds(2), event -> anim.pause()),
    new KeyFrame(Duration.seconds(3), event -> anim.play())
);
playtime.play();

【讨论】：

【解决方案2】：

如果你想保留这个动画，你可以使用插值器插入“暂停”，方法是保持值相同一段时间：

public class PauseInterpolator extends Interpolator {

    private final double pauseStart;
    private final double pauseEnd;
    private final double rate;
    private final double breakFraction;

    /**
     * Constructor. It's required that {@literal pauseEnd - pauseStart < 1}.
     * @param pauseStart the start of the pause in interval [0.0, 1.0].
     * @param pauseEnd the end of the pause in interval [0.0, 1.0]. Must be
     * greater then {@literal pauseStart}.
     */
    public PauseInterpolator(double pauseStart, double pauseEnd) {
        if (pauseStart > pauseEnd || pauseStart < 0 || pauseEnd > 1 || (pauseEnd == 1 && pauseStart == 0) ) {
            throw new IllegalArgumentException();
        }
        this.pauseStart = pauseStart;
        this.pauseEnd = pauseEnd;
        this.rate = 1 / (1 + pauseStart - pauseEnd);
        this.breakFraction = this.rate * pauseStart;
    }

    @Override
    protected double curve(double t) {
        if (t < pauseStart) {
            return t * rate;
        } else if (t > pauseEnd) {
            return breakFraction + (t - pauseEnd) * rate;
        } else {
            return breakFraction;
        }
    }

}

...
// time to pause : pause duration : time from pause to end = 1 : 1 : 1
anim.setInterpolator(new PauseInterpolator(1d/3, 2d/3));
...

请注意，这种方式需要将持续时间设置为动画时间加上暂停持续时间。

【讨论】：