逐渐淡出自定义的地图标记 [英] Gradually fade out a custom, map marker

问题描述

我正在尝试逐渐淡出自定义的Google地图标记.

I'm trying to gradually fade out a custom Google map marker.

我看过所有的帖子，说只使用DevBytes视频中的代码滴，然后将setPosition替换为setAlpha，这是我试图做的.

I've seen all the posts that say to just use the drop in code from the DevBytes video and replace the setPosition with setAlpha, which is what I have attempted to do.

问题是，无论我做什么，我的图标在处理程序期间都将变为白色，然后在完成时变为透明，而不是逐渐淡入淡出以实现完全透明.

The problem is that whatever I do, my icon just goes white for the duration of the handler and then transparent upon completion, instead of gradually fading to complete transparency.

gMap.setOnMarkerClickListener(new GoogleMap.OnMarkerClickListener() {
    @Override
    public boolean onMarkerClick(final com.google.android.gms.maps.model.Marker marker) {
        if (marker.equals(myLocationMarker)) {

            final long duration = 1000;
            final int alpha = 100;
            final long start = SystemClock.uptimeMillis();
            final Handler handler = new Handler();
            final Interpolator interpolator = new LinearInterpolator();
            handler.post(new Runnable() {
                @Override
                public void run() {
                    long elapsed = SystemClock.uptimeMillis() - start;
                    float t = interpolator.getInterpolation((float) elapsed / duration);

                    float newAlpha = alpha - (t*100);
                    if(newAlpha<0)
                        newAlpha = 0;
                    int finalAlpha = (int)Math.ceil(newAlpha);
                    System.out.println("time = "+t);
                    System.out.println("newAlpha = "+newAlpha);
                    System.out.println("finalAlpha = "+finalAlpha);
                    marker.setAlpha(finalAlpha);

                    if (t < 1.0)
                        handler.postDelayed(this, 10);
                }
            });
            return true;
        }
    });

推荐答案

我尝试使用ValueAnimator并成功:

I tried using ValueAnimator and it worked:

ValueAnimator ani = ValueAnimator.ofFloat(1, 0); //change for (0,1) if you want a fade in
ani.setDuration(5000);
ani.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
    @Override
    public void onAnimationUpdate(ValueAnimator animation) {
        marker.setAlpha((float) animation.getAnimatedValue());
    }
});
ani.start();

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