Android模拟实现滑动解锁界面

<?xml version="1.0" encoding="utf-8"?>

package com.example.a7_;

 import android.content.Context;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.graphics.Canvas;
 import android.graphics.Paint;
 import android.util.AttributeSet;
 import android.util.Log;
 import android.view.MotionEvent;
 import android.view.View;
 import android.widget.Scroller;

 /**
 * Created by Administrator on 2017.05.28.0028.
 */

 public class MyView extends View {

 private final Bitmap slidBitmap;
 private final Bitmap bgBitmap;
 private int startx;
 private int destance;
 private float endx;
 private final Scroller scroller;


 public MyView(Context context, AttributeSet attrs) {
 super(context, attrs);

 //加载图片资源
 slidBitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.switch_button);
 bgBitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.lockviewbg);
 //创建scroller对象
 scroller = new Scroller(context);
 }

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 //设置自定义控件的宽和高,,以背景图片为标准
 setMeasuredDimension(bgBitmap.getWidth(),bgBitmap.getHeight());
 }

 @Override
 protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);
 //绘制图片
 canvas.drawBitmap(slidBitmap,0,0,null);
 }

 //设置滑块的触摸事件
 @Override
 public boolean onTouchEvent(MotionEvent event) {
 switch (event.getAction()){
  case MotionEvent.ACTION_DOWN:
  //当手指按下的时候,记录坐标
  startx = (int) event.getX();
  break;
  case MotionEvent.ACTION_MOVE:
  //当手指移动的时候,记录移动的距离
  destance = (int)(event.getX()-startx);
  //限制滑块移动的区间
  if (destance<0){
   destance = 0;
  }else if (destance>bgBitmap.getWidth()-slidBitmap.getWidth()){
   destance = bgBitmap.getWidth()-slidBitmap.getWidth();
  }
  //将滑块移动至该位置
  scrollTo( -destance,0);
  break;
  case MotionEvent.ACTION_UP:
  //当手指离开时,记录手指离开的位置
  if (destance