参考官方文档:https://developer.android.com/guide/topics/graphics/prop-animation#api-overview
笔者近期接触到android动画,将诸多概念都稍微整理了一下。
一方面做一个知识的记录,另一方面也给刚接触android动画的初学者一个参考。
valueAnimator可以控制某个值的变化,通过在值变化的同时刷新View来实现动画。
下面的例子是实现TextView中值的刷新:
ValueAnimator valueAnimator = ValueAnimator.ofInt(0, 1000);
valueAnimator.setDuration(5000);
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
tv1.setText(animation.getAnimatedValue() + "");
}
});
valueAnimator.start();
ObjectAnimator可以对某个View执行属性动画,常见的属性动画有旋转,平移,缩放等。
ObjectAnimator一般是配合着AnimatorSet或者PropertyValuesHolder使用,demo如下,以下两块代码实现的是同一种效果:“btn先放大后缩小”。
属性动画有以下几种:(来自官方文档)
- translationX,translationY:从当前位置开始平移
- rotation, rotationX, rotationY:旋转
- scaleX , scaleY:缩放
- pivotX , pivotY:旋转和缩放的参照点,默认是View的中心
- x , y:平移到当前容器的某个绝对位置
- alpha:透明度
/*
ObjectAnimator + PropertyValuesHolder
*/
PropertyValuesHolder xHolder = PropertyValuesHolder.ofFloat("scaleX", 1, 1.5f, 0.8f, 1);
PropertyValuesHolder yHolder = PropertyValuesHolder.ofFloat("scaleY", 1, 1.5f, 0.8f, 1);
ObjectAnimator objectAnimator = ObjectAnimator.ofPropertyValuesHolder(btn0, xHolder, yHolder);
objectAnimator.setDuration(3000);
objectAnimator.start();
/*
* ObjectAnimator + AnimatorSet
*/
ObjectAnimator anim1 = ObjectAnimator.ofFloat(btn1, "scaleX", 1, 1.5f, 0.8f, 1);
ObjectAnimator anim2 = ObjectAnimator.ofFloat(btn1, "scaleY", 1, 1.5f, 0.8f, 1);
final AnimatorSet animatorSet = new AnimatorSet();
animatorSet.play(anim1);
animatorSet.play(anim2).with(anim1);
animatorSet.setDuration(3000);
animatorSet.start();
适合在实现“单个View连续动画”的情况下使用,使用AnimatorSet在一些情况下会比PropertyValuesHolder复杂一些。
比如要实现View的循环播放,使用PropertyValuesHolder实现的代码如下:
objectAnimator.setRepeatCount(-1);
使用AnimatorSet实现的代码如下:
animatorSet.addListener(new Animator.AnimatorListener() {
@Override
public void onAnimationStart(Animator animation) {
}
@Override
public void onAnimationEnd(Animator animation) {
if (animatorSet != null) {
animatorSet.start();
}
}
@Override
public void onAnimationCancel(Animator animation) {
}
@Override
public void onAnimationRepeat(Animator animation) {
}
});
适合在动画比较复杂的情况下使用,比如有多个View的动画需要同时进行或者交替进行,这种情况使用PropertyValuesHolder是很难实现的。
再比如,对于同一个View的动画不连续的情况,PropertyValuesHolder也比较难实现,或者说实现更加复杂。
demo中,View执行完平移之后再执行缩放逻辑。
ObjectAnimator anim11 = ObjectAnimator.ofFloat(tv2, "translationX", 200);
ObjectAnimator anim22 = ObjectAnimator.ofFloat(tv2, "scaleX", 1, 1.5f, 1f);
ObjectAnimator anim33 = ObjectAnimator.ofFloat(tv2, "scaleY", 1, 1.5f, 1f);
final AnimatorSet animatorSet2 = new AnimatorSet();
animatorSet2.play(anim11);
animatorSet2.play(anim22).after(anim11);
animatorSet2.play(anim33).with(anim22);
animatorSet2.setDuration(3000);
animatorSet2.start();
插值器可以控制动画变化的速率,设置非常简单,代码如下:
ValueAnimator valueAnimator = ValueAnimator.ofInt(0, 1000);
valueAnimator.setDuration(5000);
valueAnimator.setInterpolator(new DecelerateInterpolator());//设置插值器
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
tv1.setText(animation.getAnimatedValue() + "");
}
});
valueAnimator.start();
插值器类型:(来自官方文档)
- AccelerateDecelerateInterpolator:开始和结束的时候慢,中间快
- AccelerateInterpolator:开始的时候慢,然后加速
- AnticipateInterpolator:开始先后退,然后向前
- AnticipateOvershootInterpolator: 开始先后退,然向前到超标,最后回到最终值
- BounceInterpolator :最后会反弹
- CycleInterpolator:动画会重复一定的周期数
- DecelerateInterpolator:开始快,然后减速
- LinearInterpolator:变化匀速
- OvershootInterpolator:到达最终值后超标,再回到最终值
- TimeInterpolator:用来自定义插值器
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LinearLayout linearLayout = new LinearLayout(this);
linearLayout.setOrientation(LinearLayout.VERTICAL);
setContentView(linearLayout);
// test View
final TextView tv1 = new TextView(this);
tv1.setText(0 + "");
tv1.setTextSize(30);
linearLayout.addView(tv1);
final Button btn0 = new Button(this);
btn0.setText("btn0");
linearLayout.addView(btn0);
final Button btn1 = new Button(this);
btn1.setText("btn1");
linearLayout.addView(btn1);
final TextView tv2 = new TextView(this);
tv2.setText("tv2");
tv2.setTextSize(30);
linearLayout.addView(tv2);
final Button btn2 = new Button(this);
btn2.setText("btn2");
linearLayout.addView(btn2);
final Button btn3 = new Button(this);
btn3.setText("btn3");
linearLayout.addView(btn3);
/*
* ValueAnimator +时间插值器演示
*/
ValueAnimator valueAnimator = ValueAnimator.ofInt(0, 1000);
valueAnimator.setDuration(5000);
valueAnimator.setInterpolator(new DecelerateInterpolator());//设置插值器
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
tv1.setText(animation.getAnimatedValue() + "");
}
});
valueAnimator.start();
/*
ObjectAnimator + PropertyValuesHolder
*/
PropertyValuesHolder xHolder = PropertyValuesHolder.ofFloat("scaleX", 1, 1.5f, 0.8f, 1);
PropertyValuesHolder yHolder = PropertyValuesHolder.ofFloat("scaleY", 1, 1.5f, 0.8f, 1);
ObjectAnimator objectAnimator = ObjectAnimator.ofPropertyValuesHolder(btn0, xHolder, yHolder);
objectAnimator.setDuration(3000);
// objectAnimator.setRepeatCount(-1);
objectAnimator.start();
/*
* ObjectAnimator + AnimatorSet
*/
ObjectAnimator anim1 = ObjectAnimator.ofFloat(btn1, "scaleX", 1, 1.5f, 0.8f, 1);
ObjectAnimator anim2 = ObjectAnimator.ofFloat(btn1, "scaleY", 1, 1.5f, 0.8f, 1);
final AnimatorSet animatorSet = new AnimatorSet();
animatorSet.play(anim1);
animatorSet.play(anim2).with(anim1);
animatorSet.setDuration(3000);
animatorSet.addListener(new Animator.AnimatorListener() {
@Override
public void onAnimationStart(Animator animation) {
}
@Override
public void onAnimationEnd(Animator animation) {
if (animatorSet != null) {
animatorSet.start();
}
}
@Override
public void onAnimationCancel(Animator animation) {
}
@Override
public void onAnimationRepeat(Animator animation) {
}
});
animatorSet.start();
/*
* ObjectAnimator + AnimatorSet
*/
ObjectAnimator anim11 = ObjectAnimator.ofFloat(tv2, "translationX", 200);
ObjectAnimator anim22 = ObjectAnimator.ofFloat(tv2, "scaleX", 1, 1.5f, 1f);
ObjectAnimator anim33 = ObjectAnimator.ofFloat(tv2, "scaleY", 1, 1.5f, 1f);
final AnimatorSet animatorSet2 = new AnimatorSet();
animatorSet2.play(anim11);
animatorSet2.play(anim22).after(anim11);
animatorSet2.play(anim33).with(anim22);
animatorSet2.setDuration(3000);
animatorSet2.start();
}
}