ValueAnimator的使用

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ValueAnimator的使用

activity_main.xml文件中

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"tools:context="www.weshared.anim.MainActivity">    <TextView        android:id="@+id/tv"        android:background="@android:color/holo_blue_bright"        android:padding="16dp"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="Hello World!" />    <Button        android:id="@+id/btn"        android:layout_alignParentBottom="true"        android:layout_width="match_parent"        android:background="@android:color/holo_red_dark"        android:text="执行动画"        android:layout_height="wrap_content" /></RelativeLayout>

在res/animator目录下的value_animator.xml文件中（ValueAnimator的xml动画）

<?xml version="1.0" encoding="utf-8"?><animator  xmlns:android="http://schemas.android.com/apk/res/android"    android:duration="2000"    android:interpolator="@android:interpolator/bounce"    android:valueFrom="0px"    android:valueTo="720px"    android:valueType="intType" />

在MainActicity中

public class MainActivity extends AppCompatActivity implements View.OnClickListener, ValueAnimator.AnimatorUpdateListener {    private TextView mTextView;    private Button mButton;    private int widthPixels;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        mTextView = (TextView) findViewById(R.id.tv);        mButton = (Button) findViewById(R.id.btn);        mButton.setOnClickListener(this);        //获取屏幕的宽度        widthPixels = getResources().getDisplayMetrics().widthPixels;    }    @Override    public void onClick(View v) {        //initAnim();        initOfObject();        //initXmlAnim();    }    private void initOfObject() {        ValueAnimator animator = ValueAnimator.ofObject(new CharEvaluator(), new Character('A'), new Character('Z'));        animator.setDuration(2000).start();        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {            @Override            public void onAnimationUpdate(ValueAnimator animation) {            char animatedValue = (char) animation.getAnimatedValue();            mTextView.setText(String.valueOf(animatedValue));            mTextView.requestLayout();            }        });    }    private void initAnim() {        ValueAnimator animator = ValueAnimator.ofInt(0, widthPixels);        animator.setDuration(2000);        animator.setInterpolator(new BounceInterpolator());        animator.start();        animator.addUpdateListener(this);     }    private void initXmlAnim() {        ValueAnimator animator = (ValueAnimator) AnimatorInflater.loadAnimator(this, R.animator.value_animator);        animator.start();        animator.addUpdateListener(this);    }    @Override    public void onAnimationUpdate(ValueAnimator animation) {        int animatedValue = (int) animation.getAnimatedValue();        mTextView.setWidth(animatedValue);        mTextView.setHeight((int) (animatedValue * 0.6));        mButton.setHeight((int) (animatedValue * 0.6));        mTextView.requestLayout();        mButton.requestLayout();     }    public class CharEvaluator implements TypeEvaluator<Character> {        @Override        public Character evaluate(float fraction, Character startValue, Character endValue) {        int startInt = (int) startValue;        int endInt = (int) endValue;        int curInt = (int) (startInt + fraction * (endInt - startInt));        char result = (char) curInt;        return result;       }    }}

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