如果你的Android手机是5.0以上的系统，相信对下面这种按钮点击效果并不会陌生：
实现效果图点击此网址查看：http://www.runoob.com/wp-content/uploads/2015/07/44832111.jpg
快的那个是按下后的效果，慢的是长按后的效果！
实现逻辑：
1.我们继承ImageButton，当然你可以换成Button或者View,这里笔者想把龟放到中间才继承ImageButton
2.首先，创建两个Paint(画笔)对象，一个绘制底部背景颜色，一个绘制波纹扩散的
3.接着计算最大半径，开始半径每隔一段时间递增一次，直到等于最大半径，然后重置状态！
PS:大概的核心，刚学可能对自定义View感到陌生，没事，这里了解下即可，以后我们会讲，当然 你可以自己扣扣，注释还是蛮详细的~
实现代码：
自定义ImageButton：MyButton.java
package com.example.btnwaterripple;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.os.SystemClock;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.ViewConfiguration;
import android.widget.ImageButton;
/**
* @author lyh
* @version 创建时间：2017年11月3日
*
*/
public class MyButton extends ImageButton {
private static final int INVALIDATE_DURATION = 15; //每次刷新的时间间隔
private static int DIFFUSE_GAP = 10; //扩散半径增量
private static int TAP_TIMEOUT; //判断点击和长按的时间
private int viewWidth, viewHeight; //控件宽高
private int pointX, pointY; //控件原点坐标（左上角）
private int maxRadio; //扩散的最大半径
private int shaderRadio; //扩散的半径
private Paint bottomPaint, colorPaint; //画笔:背景和水波纹
private boolean isPushButton; //记录是否按钮被按下
private int eventX, eventY; //触摸位置的X,Y坐标
private long downTime = 0; //按下的时间
public MyButton(Context context, AttributeSet attrs) {
super(context, attrs);
initPaint();
TAP_TIMEOUT = ViewConfiguration.getLongPressTimeout();
}
/*
* 初始化画笔
* */
private void initPaint() {
colorPaint = new Paint();
bottomPaint = new Paint();
colorPaint.setColor(getResources().getColor(R.color.reveal_color));
bottomPaint.setColor(getResources().getColor(R.color.bottom_color));
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (downTime == 0) downTime = SystemClock.elapsedRealtime();
eventX = (int) event.getX();
eventY = (int) event.getY();
//计算最大半径：
countMaxRadio();
isPushButton = true;
postInvalidateDelayed(INVALIDATE_DURATION);
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
if(SystemClock.elapsedRealtime() - downTime < TAP_TIMEOUT){
DIFFUSE_GAP = 30;
postInvalidate();
}else{
clearData();
}
break;
}
return super.onTouchEvent(event);
}
@Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
if(!isPushButton) return; //如果按钮没有被按下则返回
//绘制按下后的整个背景
canvas.drawRect(pointX, pointY, pointX + viewWidth, pointY + viewHeight, bottomPaint);
canvas.save();
//绘制扩散圆形背景
canvas.clipRect(pointX, pointY, pointX + viewWidth, pointY + viewHeight);
canvas.drawCircle(eventX, eventY, shaderRadio, colorPaint);
canvas.restore();
//直到半径等于最大半径
if(shaderRadio < maxRadio){
postInvalidateDelayed(INVALIDATE_DURATION,
pointX, pointY, pointX + viewWidth, pointY + viewHeight);
shaderRadio += DIFFUSE_GAP;
}else{
clearData();
}
}
/*
* 计算最大半径的方法
* */
private void countMaxRadio() {
if (viewWidth > viewHeight) {
if (eventX < viewWidth / 2) {
maxRadio = viewWidth - eventX;
} else {
maxRadio = viewWidth / 2 + eventX;
}
} else {
if (eventY < viewHeight / 2) {
maxRadio = viewHeight - eventY;
} else {
maxRadio = viewHeight / 2 + eventY;
}
}
}
/*
* 重置数据的方法
* */
private void clearData(){
downTime = 0;
DIFFUSE_GAP = 10;
isPushButton = false;
shaderRadio = 0;
postInvalidate();
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
this.viewWidth = w;
this.viewHeight = h;
}
}
colors.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="reveal_color">#FFFFFF</color>
<color name="bottom_color">#3086E4</color>
<color name="bottom_bg">#40BAF8</color>
</resources>
activity_main.xml：
<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=".MainActivity" >
<com.example.btnwaterripple.MyButton
android:id="@+id/myBtn"
android:layout_width="match_parent"
android:layout_height="64dp"
android:layout_margin="5dp"
android:background="@color/bottom_bg"
android:scaleType="center"
android:src="@drawable/rad_selected" />
</RelativeLayout>