PropertyAnimation屬性動畫 ValueAnimator實現自由落體 拋物線

1.佈局activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <ImageView
        android:id="@+id/iv"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_centerInParent="true"
        android:src="@mipmap/a" />


    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:orientation="horizontal">

        <Button
            android:id="@+id/bt_verticalRun"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="自由落體" />

        <Button
            android:id="@+id/bt_parabola"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="拋物線" />
    </LinearLayout>

</RelativeLayout>

2.代碼

package com.baway.zhengshuai20170415property;

import android.animation.ObjectAnimator;
import android.animation.PropertyValuesHolder;
import android.animation.TypeEvaluator;
import android.animation.ValueAnimator;
import android.graphics.PointF;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.Display;
import android.view.View;
import android.view.animation.LinearInterpolator;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private ImageView iv;
    private Button bt_parabola;
    private Button bt_verticalRun;
    private int screenHeightPixels;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        iv = (ImageView) findViewById(R.id.iv);
        bt_parabola = (Button) findViewById(R.id.bt_parabola);
        bt_verticalRun = (Button) findViewById(R.id.bt_verticalRun);
        bt_parabola.setOnClickListener(this);
        bt_verticalRun.setOnClickListener(this);
        //獲取屏幕
        DisplayMetrics metrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(metrics);
        screenHeightPixels = metrics.heightPixels;
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.bt_parabola://拋物線
                //獲取動畫執行類
                ValueAnimator valueAnimator = new ValueAnimator();
                //設置起始座標
                valueAnimator.setObjectValues(new PointF(0, 0));
                valueAnimator.setDuration(3000);
                //插值器
                valueAnimator.setInterpolator(new LinearInterpolator());
                //設置類型估值
                valueAnimator.setEvaluator(new TypeEvaluator<PointF>() {

                    @Override
                    public PointF evaluate(float fraction, PointF startValue, PointF endValue) {
                        // fraction = t / duration
                        PointF pointF = new PointF();
                        // x方向200px/s ，則y方向0.5 * 10 * t
                        pointF.x = 200 * fraction * 3;
                        pointF.y = 300 * (fraction * 3) * (fraction * 3);
                        return pointF;
                    }
                });
                valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                    @Override
                    public void onAnimationUpdate(ValueAnimator animation) {
                        PointF pointF = (PointF) animation.getAnimatedValue();
                        //獲取最終位置
                        iv.setX(pointF.x);
                        iv.setY(pointF.y);
                    }
                });
                valueAnimator.start();

                break;
            case R.id.bt_verticalRun://自由落體
                //動畫執行類
                ValueAnimator animator = ValueAnimator.ofFloat(0, screenHeightPixels - iv.getHeight());
                animator.setTarget(iv);
                animator.setDuration(4000).start();
                animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                    @Override
                    public void onAnimationUpdate(ValueAnimator animation) {
                        //獲取平移位置
                        float hight = (float) animation.getAnimatedValue();
                        iv.setTranslationY(hight);
                    }
                });
                break;
        }
    }
}