水波纹

　

水波纹

public class weater extends View {

    private Path mPathTop,mPathBottom;
    private Paint mPaintTop,mPaintBottom;
    float φ;

    public weater(context context) {
        super(context);
        init(context);
    }

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

    public weater(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(context);
    }
    private void init(Context context) {
        mPathTop = new Path();
        mPathBottom = new Path();

        mPaintTop = new Paint();
        mPaintTop.setcolor(Color.WHITE);
        mPaintTop.setAntiAlias(true);
        mPaintBottom = new Paint();
        mPaintBottom.setColor(Color.WHITE);
        mPaintBottom.setAntiAlias(true);
        mPaintBottom.setAlpha(10);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        mPathTop.reset();
        mPathBottom.reset();
        mPathTop.moveTo(getLeft(),getBottom());
        mPathBottom.moveTo(getLeft(),getTop());

        double mY = Math.PI*2/getWidth();
        float y,y2;
        φ-=0.1f;
        for(float x=0;x<=getWidth();x+=20){
            y= (float) (10*Math.cos(mY*x+φ))+10;
            y2 = (float) (10*Math.sin(mY*x+φ));
            mPathTop.lineTo(x,y);
            mPathBottom.lineTo(x,y2);
            listener.shezhiheight(y-20);
        }

        mPathTop.lineTo(getRight(),getBottom());
        mPathBottom.lineTo(getRight(),getBottom());

        canvas.drawPath(mPathTop,mPaintTop);
        canvas.drawPath(mPathBottom,mPaintBottom);
        postinvalidateDelayed(20);
    }
    private WeaterListener listener;
    public void  reslt(WeaterListener listener){
        this.listener = listener;
    }
    public interface WeaterListener{
        void shezhiheight(float a);
    }
}

=============================Activity========================================

protected void onCreate(@Nullable Bundle savedinstanceState) {
    super.onCreate(savedInstanceState);
    setcontentView(R.layout.activity_weater);
    imageView = (ImageView) findViewById(R.id.img_weater);
    water_view = (weater) findViewById(R.id.water_view);
    final relativelayout.layoutparams layoutParams = (RelativeLayout.LayoutParams) imageView.getLayoutParams();
    water_view.reslt(new weater.WeaterListener() {
        @Override
        public void shezhiheight(float a) {
            layoutParams.setMargins(0,0,0, (int) a);
            imageView.setLayoutParams(layoutParams);
        }
    });

}

==============================布局文件===========================================

<RelativeLayout
    Android:background="#d43c3c"
    android:layout_width="match_parent"
    android:layout_height="200dp">
    <ImageView
        android:id="@+id/img_weater"
        android:layout_above="@+id/water_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:src="@mipmap/ic_launcher"/>
    <yuekao.zhaoyufeng.bwie.com.day03_demo1.weater
        android:layout_alignParentBottom="true"
        android:id="@+id/water_view"
        android:layout_width="match_parent"
        android:layout_height="20dp" />
</RelativeLayout>

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