Android move object along a path

Question

I ave created a path a circle and displayed both of them on screen as follows:

public void onDraw(Canvas canvas){

        Path sPath = new Path();
        s         


        

Answer 1

The right way to do this is with ContraintLayout and then add a keyframe between the points on the path you want to animate, as described here: https://medium.com/google-developers/defining-motion-paths-in-motionlayout-6095b874d37.

Answer 2

v21+: this creates a quadratic bezier curve on a path and animates myView along it.

final Path path = new Path();
path.quadTo(controlX, controlY, finalX, finalY);
ObjectAnimator.ofFloat(myView, View.X, View.Y, path).start();

Answer 3

Here are the animators I use:

Purpose: Move View "view" along Path "path"

v21+:

ValueAnimator pathAnimator = ObjectAnimator.ofFloat(view, "x", "y", path)

v11+:

ValueAnimator pathAnimator = ValueAnimator.ofFloat(0.0f, 1.0f);

pathAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
float[] point = new float[2];

@Override
    public void onAnimationUpdate(ValueAnimator animation) {
        float val = animation.getAnimatedFraction();
        PathMeasure pathMeasure = new PathMeasure(path, true);
        pathMeasure.getPosTan(pathMeasure.getLength() * val, point, null);
        view.setX(point[0]);
        view.setY(point[1]);
    }
});

Answer 4

You would need to move your circle a little bit each frame towards the next waypoint and detect once it gets there, then start moving toward the next. There is no built in system that I know of.

Answer 5

Yes, it's possible to move image along path. I will provide simple solution to show the principle. The following code will animate the circle along the path.

int iCurStep = 0;// current animation step

@Override
protected void onDraw(Canvas canvas) {
    PathMeasure pm = new PathMeasure(sPath, false);
    float fSegmentLen = pm.getLength() / 20;//we'll get 20 points from path to animate the circle
    float afP[] = {0f, 0f};

    if (iCurStep <= 20) {
        pm.getPosTan(fSegmentLen * iCurStep, afP, null);
        canvas.drawCircle(afP[0],afP[1],20,pathPaint);
        iCurStep++;
        invalidate();
    } else {
        iCurStep = 0;
    };
};