在android中我們要經常用到看似一個沒有時間限制的重複動畫,如最常見的下拉重新整理和上拉載入更多的loading載入動畫:

    今天嘗試了三種動畫(以旋轉為例):

package com.example.anim.anim;

import android.animation.Animator;
import android.animation.ObjectAnimator;
import android.animation.ValueAnimator;
import android.view.View;
import android.view.animation.Animation;
import
 
 android.view.animation.LinearInterpolator;
import android.view.animation.RotateAnimation;

/**
 * Created by houruixiang on 2017/8/15.
 */

public class SimpleAnim {

    private static ValueAnimator valueAnimator;

    public static void startAnim(View view){
        RotateAnimation rotateAnimation = new
 
 RotateAnimation(0, 360f,
                Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
        rotateAnimation.setDuration(2000);
        rotateAnimation.setFillAfter(true);
        rotateAnimation.setRepeatCount(-1);
        view.startAnimation(rotateAnimation);
    }

    public static
 
 void startOjAnim(View view){

        ObjectAnimator rotation = ObjectAnimator.ofFloat(view, "rotation", 0, 360f);

        rotation.setDuration(2000);
        rotation.setRepeatCount(-1);
        rotation.start();


    }


    public static void startValueAnim(final View view){
        valueAnimator = ValueAnimator.ofFloat(0f, 360.0f);
        //valueAnimator.setTarget(view);
        //valueAnimator.setRepeatMode(ValueAnimator.RESTART);
        valueAnimator.setRepeatCount(ValueAnimator.INFINITE);
        valueAnimator.setDuration(1000);

        valueAnimator.start();
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator valueAnimator) {
                float animatedValue = (float) valueAnimator.getAnimatedValue();
                view.setRotation(animatedValue);
            }
        });


    }

}

都存在這個問題,之前遇到這個問題,會誤認為是補間動畫和屬性動畫的差別,今天試了之後,都一樣;抑或是restart的延遲造成的
其實都不是,只是動畫的執行不是勻速的,所以當設定一個勻速插值器之後就完美解決問題;看下面程式碼(以valueAnimation為例):

public static void startValueAnim(final View view){
        valueAnimator = ValueAnimator.ofFloat(0f, 360.0f);
        //valueAnimator.setTarget(view);
        //valueAnimator.setRepeatMode(ValueAnimator.RESTART);
        valueAnimator.setRepeatCount(ValueAnimator.INFINITE);
        valueAnimator.setDuration(1000);
        valueAnimator.setInterpolator(new LinearInterpolator());
        valueAnimator.start();
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator valueAnimator) {
                float animatedValue = (float) valueAnimator.getAnimatedValue();
                view.setRotation(animatedValue);
            }
        });


    }

關鍵程式碼:valueAnimator.setInterpolator(new LinearInterpolator());
ok,比較簡單,感謝閱讀,共同進步