先上特效,我們從特效上分析實現邏輯:
按照支付寶上中間是一個圖片,點擊之後波紋向外擴散。
我們從自定義控件入手:
1.自定義控件中間畫圓
2.半徑不斷增加,不斷的重繪圓(此時效果應該是,一個圓不斷的向外擴散)
3.重繪圓期間定時添加一個圓,同理,不斷增加該圓的半徑
4.重繪每個圓之前,我們不斷改變畫筆的透明度實現不斷變淺直至透明(此時效果基本實現)
優化
按照第三個步揍,我們可以添加一個半徑集合,當圓的半徑超過屏幕一般,集合通過迭代器移除該半徑,控制集合的長度,防止內存溢出。
代碼:
package com.zkr.cn.slidinglayout;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.os.Handler;
import android.util.AttributeSet;
import android.view.View;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
/**
* @Description: ---------支付寶咻一咻
* @author: ---------------LF
* @date: -----------------2016/11/14 17:06
*/
public class XiuXiuView extends View {
//自定義控件的寬高,中間圖像的寬高
private int width,height,mBitmapWidth,mBitmapHeight;
private Bitmap btnBitmap;
private Paint mPaint;
//每個圓的起始半徑
private int radius;
private long current= System.currentTimeMillis();
private List<Integer> radiusList=new ArrayList<>();
public static long INTERVAL_NARMAL=300;
public static long INTERVAL_LONG=500;
public static long INTERVAL_SHORT=120;
private long intervalTime=INTERVAL_NARMAL;
/**
* 設置兩波紋間隔時間(即波紋密度)
* @param intervalTime INTERVAL_NARMAL,INTERVAL_LONG,INTERVAL_SHORT
*/
public void setIntervalTime(long intervalTime) {
this.intervalTime = intervalTime;
}
private Handler mHandler=new Handler();
private Runnable runnable=new Runnable() {
@Override
public void run() {
invalidate();
if(System.currentTimeMillis()-current>intervalTime){
radiusList.add(mBitmapWidth/2);
current=System.currentTimeMillis();
}
//每個圓圈半徑不斷增加向外擴展
for (int i=0;i<radiusList.size();i++){
radiusList.set(i,radiusList.get(i)+4);
}
//性能優化
Iterator iterator=radiusList.iterator();
while (iterator.hasNext()){
Integer integer= (Integer) iterator.next();
if(integer>=width/2){
iterator.remove();
}
}
mHandler.postDelayed(runnable,16);
}
};
public XiuXiuView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
btnBitmap= BitmapFactory.decodeResource(getResources(),R.mipmap.ic_launcher);
mBitmapWidth=btnBitmap.getWidth();
mBitmapHeight=btnBitmap.getHeight();
radius=mBitmapWidth/2;
radiusList.add(radius);
mPaint=new Paint();
mPaint.setColor(getResources().getColor(R.color.xiuxiu));
mPaint.setStyle(Paint.Style.FILL);
}
@Override
protected void onDraw(Canvas canvas) {
width=canvas.getWidth();
height=canvas.getHeight();
for (int i=0;i<radiusList.size();i++){
/**
* 定義透明度從半透明到透明不斷降低,半透明:125
* 當前圓半徑/屏幕寬度一般=當前圓半徑擴展的比率
* 當前圓半徑擴展的比率*125=半透明的比率值(此值是逐漸變大,即從透明到不透明)
*/
mPaint.setAlpha(125-125*radiusList.get(i)/(width/2));
canvas.drawCircle(width/2,height/2,radiusList.get(i),mPaint);
}
canvas.drawBitmap(btnBitmap,(width-mBitmapWidth)/2,(height-mBitmapHeight)/2,null);
super.onDraw(canvas);
}
public void start(){
mHandler.postDelayed(runnable,16);
}
}
我們在XiuXiuView中添加了一個屬性setIntervalTime,此屬性用來設置波紋密度。Activity代碼:
xv= (XiuXiuView) findViewById(R.id.xv);
xv.setIntervalTime(XiuXiuView.INTERVAL_NARMAL);
xv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
xv.start();
}
});