Android 自定義圓實作屬性動畫抛物線效果

自定義圓：

public class Yuan extends View{

    public static final float RADIUS=50f;
    private Point currentPoint;
    private circleColor currentColor;
    private Paint paint=new Paint();

    public Yuan(Context context) {
        super(context);
    }

    public Yuan(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public Yuan(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

    }

    //确定控件的位置和顔色
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (currentPoint==null){
            currentColor=new circleColor(Color.BLUE);
            paint.setColor(currentColor.getColor());
            currentPoint=new Point(RADIUS,RADIUS);
            canvas.drawCircle(currentPoint.getX(),currentPoint.getY(),RADIUS,paint);
            starAnim();
        }else {
            paint.setColor(currentColor.getColor());
            canvas.drawCircle(currentPoint.getX(),currentPoint.getY(),RADIUS,paint);
        }
    }
    //開始設計動畫的效果
    private void starAnim() {
        Point startPoint=new Point(RADIUS,RADIUS);
        Point endPoint=new Point(getWidth()-RADIUS,getHeight()-RADIUS);
        final ValueAnimator value=ValueAnimator.ofObject(new PointEvaluator(),startPoint,endPoint);
        value.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                if (animation!=null){
                    currentPoint=(Point)animation.getAnimatedValue();
                    invalidate();
                }
            }
        });
    }

    //自己定義的模式裡面計算開始到結束，原點和顔色的內插補點
    class PointEvaluator implements TypeEvaluator {

        @Override
        public Object evaluate(float fraction, Object startValue, Object endValue) {
            Point startPoin=(Point)startValue;
            Point endPoin=(Point)endValue;
            float x = startPoin.getX() + fraction * (endPoin.getX() - startPoin.getX());
            float y = startPoin.getY() + fraction * (endPoin.getY() - startPoin.getY());
            return new Point(x,y);
        }
    }
    class ColorEvalustor implements TypeEvaluator{
        int count;
        @Override
        public Object evaluate(float fraction, Object startValue, Object endValue) {
            circleColor startColor=(circleColor)startValue;
            circleColor endColor=(circleColor)endValue;

            int alpha=(int)(Color.alpha(startColor.getColor())+fraction*(Color.alpha(endColor.getColor())-Color.alpha(startColor.getColor())));
            int red=(int)(Color.red(startColor.getColor())+fraction*(Color.red(endColor.getColor())-Color.red(startColor.getColor())));
            int green=(int)(Color.green(startColor.getColor())+fraction*(Color.green(endColor.getColor())-Color.green(endColor.getColor())));
            int blue=(int)(Color.blue(startColor.getColor())+fraction*(Color.blue(endColor.getColor())-Color.blue(endColor.getColor())));


            return new circleColor(Color.argb(alpha,red,green,blue));
        }
    }
    public class circleColor{
        private int color;

        @Override
        public String toString() {
            return "circleColor{" +
                    "color=" + color +
                    '}';
        }

        public int getColor() {
            return color;
        }

        public void setColor(int color) {
            this.color = color;
        }

        public circleColor(int color) {
            this.color = color;
        }
    }

    public class Point {
        private float x;
        private float y;

        public Point(float x, float y) {
            this.x = x;
            this.y = y;
        }

        @Override
        public String toString() {
            return "Point{" +
                    "x=" + x +
                    ", y=" + y +
                    '}';
        }

        public float getX() {
            return x;
        }

        public void setX(float x) {
            this.x = x;
        }

        public float getY() {
            return y;
        }

        public void setY(float y) {
            this.y = y;
        }
    }
}      
   

布局：activity_main.xml      

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.bwei.yuekao.MainActivity">

    <com.bwei.yuekao.Yuan
        android:id="@+id/yuan"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</RelativeLayout>
      
   

MainActivity：      

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final Yuan yuan= (Yuan) findViewById(R.id.yuan);

        ValueAnimator valueAnimator=new ValueAnimator();
        valueAnimator.setDuration(5000);
        valueAnimator.setObjectValues(new PointF(0,0));
        valueAnimator.setInterpolator(new LinearInterpolator());
        valueAnimator.setEvaluator(new TypeEvaluator<PointF>()
        {

            @Override
            public PointF evaluate(float v, PointF pointF, PointF t1) {
                PointF point=new PointF();
                point.x=200*v*3;
                point.y=0.5f*200*(v*3)*(v*3);
                return point;
            }
        });
        valueAnimator.start();
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator valueAnimator)
            {
                PointF point= (PointF) valueAnimator.getAnimatedValue();
                yuan.setX(point.x);
                yuan.setY(point.y);
            }
        });
        //判斷動畫是否結束
        valueAnimator.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                super.onAnimationEnd(animation);
                //動畫結束之後的邏輯
                Intent intent=new Intent(MainActivity.this,TwoActivity.class);
                startActivity(intent);
                finish();
            }
        });
    }
}