水波纹简单使用

**

先写布局

**

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
android:orientation="vertical"
tools:context=".MainActivity">

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="200dp"
    android:background="@color/colorLv">

    <ImageView
        android:id="@+id/gif"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_above="@+id/wat"
        android:layout_centerHorizontal="true"
        android:src="@drawable/ic_launcher_background" />

    <com.mfy.text.demo01_waterbowen.Water
        android:id="@+id/wat"
        android:layout_width="match_parent"
        android:layout_height="20dp"
        android:layout_alignParentBottom="true" />
</RelativeLayout>

**

在定义一个Water类

**
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.View;

//继承view 实现前三个方法
public class Water extends View {
private Paint paintTop;
private Paint paintBottom;
private Path pathTop;
private Path pathBottom;
//封装浮点型的φ  去下面初始值
private float φ;
private WaterListener waterListener;

public Water(Context context) {
    super(context);
    //初始化方法传上下文
    init(context);
}

public Water(Context context, @Nullable AttributeSet attrs) {
    super(context, attrs);
    //初始化方法传上下文
    init(context);
}

public Water(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    //初始化方法传上下文
    init(context);
}

private void init(Context context) {
    //new 画笔 提上去
    paintTop = new Paint();
    //设置颜色
    paintTop.setColor(Color.RED);
    //设置抗锯齿 AntiAlias为真
    paintTop.setAntiAlias(true);
    paintBottom = new Paint();
    //设置颜色
    paintBottom.setColor(Color.BLUE);
    //设置抗锯齿 AntiAlias为真
    paintBottom.setAntiAlias(true);
    //第二个设置透明度 Alpha 30
    paintBottom.setAlpha(30);

    //new 路径
    pathTop = new Path();
    pathBottom = new Path();
}

//重写ondraw  方法
@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    //一定要记得路径都重置 要不然不动
    pathTop.reset();
    pathBottom.reset();

    //路径开始move to 设置左下
    pathTop.moveTo(getLeft(), getBottom());
    pathBottom.moveTo(getLeft(), getBottom());

    //math .pi *2 /获取宽度  返回值 小数点 y
    double y = Math.PI * 2 / getWidth();
    //直接初始值 -=0.1f
    φ -= 0.1f;

    //循环浮点型x +=20 条件小于等于获取宽度
    for (float x = 0; x <= getWidth(); x += 20) {
        //路径lineto x math  .cos  sin x*y  *10 括号强转 +φ +10
        pathTop.lineTo(x, (float) (10 * Math.cos(x * y + φ) + 10));
        float y1 = (float) (10 * Math.sin(x * y + φ));
        pathBottom.lineTo(x, y1);
        //调用接口方法传y1 上面提出去 把第二个
        waterListener.success(y1);
    }

    //路径终止用line to 设置右下
    pathTop.lineTo(getRight(), getBottom());
    pathBottom.lineTo(getRight(), getBottom());

    //用传进来的can draw  画笔 路径
    canvas.drawPath(pathTop, paintTop);
    canvas.drawPath(pathBottom, paintBottom);

    //设置时间 post in da de 20
    postInvalidateDelayed(20);
}

//公共的方法 result接口回调 括号里 传接口
public void result(WaterListener waterListener) {
    //接口返回值 this . 提上去
    this.waterListener = waterListener;
}

//公共的接口 水监听
public interface WaterListener {
    //写一个成功的方法 传浮点型的y1
    void success(float y1);
}

}

**

在写MainActivity

**
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.RelativeLayout;

public class MainActivity extends AppCompatActivity {

private ImageView gif;
private Water wat;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //获取控件 强转控件 提上去
    gif = (ImageView) findViewById(R.id.gif);
    wat = (Water) findViewById(R.id.wat);

    //给gif  获取布局参数 强转re  相对布局
    final RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) gif.getLayoutParams();
    //用wat 布局调用回调方法 括号里 new
    wat.result(new Water.WaterListener() {
        @Override
        public void success(float y1) {
            //给属性对象 设置 Margins赋值  四个值 3个0 y1 强转
            layoutParams.setMargins(0, 0, 0, (int) y1);
            //给图片设置属性参数
            gif.setLayoutParams(layoutParams);
        }
    });
}

}