滑动开关按钮SlideSwich

iphone上有开关控件，很漂亮，其实android4.0以后也有switch控件，但是只能用在4.0以后的系统中，这就失去了其使用价值，而且我觉得它的界面也不是很好看。最近看到了百度魔拍上面的一个控件，觉得很漂亮啊，然后反编译了下，尽管没有混淆过，但是还是不好读，然后就按照自己的想法写了个，功能和百度魔拍类似。

下面是百度魔拍的效果和SlideSwitch的效果

apk下载地址：http://home.ustc.edu.cn/~voa/res/HelloJni.apk

2.原理

继承自view类，override其onDraw函数，把两个背景图（一个灰的一个红的）和一个开关图（圆开关）通过canvas画出来；同时override其onTouchEvent函数，实现滑动效果；最后开启一个线程做动画，实现缓慢滑动的效果。

3. 代码

//SlideSwitch.java

 package com.example.hellojni;

 import android.content.Context;
 import android.content.res.Resources;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Paint;
 import android.graphics.Rect;
 import android.graphics.Typeface;
 import android.util.AttributeSet;
 import android.util.Log;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewGroup.LayoutParams;

 /**
  * SlideSwitch 仿iphone滑动开关组件，仿百度魔图滑动开关组件
  * 组件分为三种状态：打开、关闭、正在滑动<br/>
  * 使用方法：
  * <pre>SlideSwitch slideSwitch = new SlideSwitch(this);
  *slideSwitch.setOnSwitchChangedListener(onSwitchChangedListener);
  *linearLayout.addView(slideSwitch);
 </pre>
 注：也可以加载在xml里面使用
  * @author scott
  *
  */
 public class SlideSwitch extends View
 {
     public static final String TAG = "SlideSwitch";
     public static final int SWITCH_OFF = 0;//关闭状态
     public static final int SWITCH_ON = 1;//打开状态
     public static final int SWITCH_SCROLING = 2;//滚动状态

     //用于显示的文本
     private String mOnText = "打开";
     private String mOffText = "关闭";

     private int mSwitchStatus = SWITCH_OFF;

     private boolean mHasScrolled = false;//表示是否发生过滚动

     private int mSrcX = 0, mDstX = 0;

     private int mBmpWidth = 0;
     private int mBmpHeight = 0;
     private int mThumbWidth = 0;

     private     Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);

     private OnSwitchChangedListener mOnSwitchChangedListener = null;

     //开关状态图
     Bitmap mSwitch_off, mSwitch_on, mSwitch_thumb;

     public SlideSwitch(Context context)
     {
         this(context, null);
     }

     public SlideSwitch(Context context, AttributeSet attrs)
     {
         super(context, attrs);
         init();
     }

     public SlideSwitch(Context context, AttributeSet attrs, int defStyle)
     {
         super(context, attrs, defStyle);
         init();
     }

     //初始化三幅图片
     private void init()
     {
         Resources res = getResources();
         mSwitch_off = BitmapFactory.decodeResource(res, R.drawable.bg_switch_off);
         mSwitch_on = BitmapFactory.decodeResource(res, R.drawable.bg_switch_on);
         mSwitch_thumb = BitmapFactory.decodeResource(res, R.drawable.switch_thumb);
         mBmpWidth = mSwitch_on.getWidth();
         mBmpHeight = mSwitch_on.getHeight();
         mThumbWidth = mSwitch_thumb.getWidth();
     }

     @Override
     public void setLayoutParams(LayoutParams params)
     {
         params.width = mBmpWidth;
         params.height = mBmpHeight;
         super.setLayoutParams(params);
     }

     /**
      * 为开关控件设置状态改变监听函数
      * @param onSwitchChangedListener 参见 {@link OnSwitchChangedListener}
      */
     public void setOnSwitchChangedListener(OnSwitchChangedListener onSwitchChangedListener)
     {
         mOnSwitchChangedListener = onSwitchChangedListener;
     }

     /**
      * 设置开关上面的文本
      * @param onText  控件打开时要显示的文本
      * @param offText  控件关闭时要显示的文本
      */
     public void setText(final String onText, final String offText)
     {
         mOnText = onText;
         mOffText =offText;
         invalidate();
     }

     /**
      * 设置开关的状态
      * @param on 是否打开开关 打开为true 关闭为false
      */
     public void setStatus(boolean on)
     {
         mSwitchStatus = ( on ? SWITCH_ON : SWITCH_OFF);
     }

     @Override
     public boolean onTouchEvent(MotionEvent event)
     {
         int action = event.getAction();
         Log.d(TAG, "onTouchEvent  x="  + event.getX());
         switch (action) {
         case MotionEvent.ACTION_DOWN:
             mSrcX = (int) event.getX();
             break;
         case MotionEvent.ACTION_MOVE:
             mDstX = Math.max( (int) event.getX(), 10);
             mDstX = Math.min( mDstX, 62);
             if(mSrcX == mDstX)
                 return true;
             mHasScrolled = true;
             AnimationTransRunnable aTransRunnable = new AnimationTransRunnable(mSrcX, mDstX, 0);
             new Thread(aTransRunnable).start();
             mSrcX = mDstX;
             break;
         case MotionEvent.ACTION_UP:
             if(mHasScrolled == false)//如果没有发生过滑动，就意味着这是一次单击过程
             {
                 mSwitchStatus = Math.abs(mSwitchStatus-1);
                 int xFrom = 10, xTo = 62;
                 if(mSwitchStatus == SWITCH_OFF)
                 {
                     xFrom = 62;
                     xTo = 10;
                 }
                 AnimationTransRunnable runnable = new AnimationTransRunnable(xFrom, xTo, 1);
                 new Thread(runnable).start();
             }
             else
             {
                 invalidate();
                 mHasScrolled = false;
             }
             //状态改变的时候 回调事件函数
             if(mOnSwitchChangedListener != null)
             {
                 mOnSwitchChangedListener.onSwitchChanged(this, mSwitchStatus);
             }
             break;

         default:
             break;
         }
         return true;
     }

     @Override
     protected void onSizeChanged(int w, int h, int oldw, int oldh)
     {
         super.onSizeChanged(w, h, oldw, oldh);
     }

     @Override
     protected void onDraw(Canvas canvas)
     {
         super.onDraw(canvas);
         //绘图的时候 内部用到了一些数值的硬编码，其实不太好，
         //主要是考虑到图片的原因，图片周围有透明边界，所以要有一定的偏移
         //硬编码的数值只要看懂了代码，其实可以理解其含义，可以做相应改进。
         mPaint.setTextSize(14);
         mPaint.setTypeface(Typeface.DEFAULT_BOLD);

         if(mSwitchStatus == SWITCH_OFF)
         {
             drawBitmap(canvas, null, null, mSwitch_off);
             drawBitmap(canvas, null, null, mSwitch_thumb);
             mPaint.setColor(Color.rgb(105, 105, 105));
             canvas.translate(mSwitch_thumb.getWidth(), 0);
             canvas.drawText(mOffText, 0, 20, mPaint);
         }
         else if(mSwitchStatus == SWITCH_ON)
         {
             drawBitmap(canvas, null, null, mSwitch_on);
             int count = canvas.save();
             canvas.translate(mSwitch_on.getWidth() - mSwitch_thumb.getWidth(), 0);
             drawBitmap(canvas, null, null, mSwitch_thumb);
             mPaint.setColor(Color.WHITE);
             canvas.restoreToCount(count);
             canvas.drawText(mOnText, 17, 20, mPaint);
         }
         else //SWITCH_SCROLING
         {
             mSwitchStatus = mDstX > 35 ? SWITCH_ON : SWITCH_OFF;
             drawBitmap(canvas, new Rect(0, 0, mDstX, mBmpHeight), new Rect(0, 0, (int)mDstX, mBmpHeight), mSwitch_on);
             mPaint.setColor(Color.WHITE);
             canvas.drawText(mOnText, 17, 20, mPaint);

             int count = canvas.save();
             canvas.translate(mDstX, 0);
             drawBitmap(canvas, new Rect(mDstX, 0, mBmpWidth, mBmpHeight),
                           new Rect(0, 0, mBmpWidth - mDstX, mBmpHeight), mSwitch_off);
             canvas.restoreToCount(count);

             count = canvas.save();
             canvas.clipRect(mDstX, 0, mBmpWidth, mBmpHeight);
             canvas.translate(mThumbWidth, 0);
             mPaint.setColor(Color.rgb(105, 105, 105));
             canvas.drawText(mOffText, 0, 20, mPaint);
             canvas.restoreToCount(count);

             count = canvas.save();
             canvas.translate(mDstX - mThumbWidth / 2, 0);
             drawBitmap(canvas, null, null, mSwitch_thumb);
             canvas.restoreToCount(count);
         }

     }

     public void drawBitmap(Canvas canvas, Rect src, Rect dst, Bitmap bitmap)
     {
         dst = (dst == null ? new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight()) : dst);
         Paint paint = new Paint();
         canvas.drawBitmap(bitmap, src, dst, paint);
     }

     /**
      * AnimationTransRunnable 做滑动动画所使用的线程
      */
     private class AnimationTransRunnable implements Runnable
     {
         private int srcX, dstX;
         private int duration;

         /**
          * 滑动动画
          * @param srcX 滑动起始点
          * @param dstX 滑动终止点
          * @param duration 是否采用动画，1采用，0不采用
          */
         public AnimationTransRunnable(float srcX, float dstX, final int duration)
         {
             this.srcX = (int)srcX;
             this.dstX = (int)dstX;
             this.duration = duration;
         }

         @Override
         public void run()
         {
             final int patch = (dstX > srcX ? 5 : -5);
             if(duration == 0)
             {
                 SlideSwitch.this.mSwitchStatus = SWITCH_SCROLING;
                 SlideSwitch.this.postInvalidate();
             }
             else
             {
                 Log.d(TAG, "start Animation: [ " + srcX + " , " + dstX + " ]");
                 int x = srcX + patch;
                 while (Math.abs(x-dstX) > 5)
                 {
                     mDstX = x;
                     SlideSwitch.this.mSwitchStatus = SWITCH_SCROLING;
                     SlideSwitch.this.postInvalidate();
                     x += patch;
                     try
                     {
                         Thread.sleep(10);
                     }
                     catch (InterruptedException e)
                     {
                         e.printStackTrace();
                     }
                 }
                 mDstX = dstX;
                 SlideSwitch.this.mSwitchStatus = mDstX > 35 ? SWITCH_ON : SWITCH_OFF;
                 SlideSwitch.this.postInvalidate();
             }
         }

     }

     public static interface OnSwitchChangedListener
     {
         /**
          * 状态改变 回调函数
          * @param status  SWITCH_ON表示打开 SWITCH_OFF表示关闭
          */
         public abstract void onSwitchChanged(SlideSwitch obj, int status);
     }

 }

// layout xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     android:background="#fdfdfd"
     android:orientation="vertical"
     android:paddingLeft="10dip"
     android:paddingRight="10dip" >

     <ImageView
         android:id="@+id/imageView1"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:src="@drawable/top" />

     <RelativeLayout
         android:layout_width="fill_parent"
         android:layout_height="wrap_content" >

         <TextView
             android:id="@+id/textView1"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:layout_alignParentLeft="true"
             android:layout_centerVertical="true"
             android:text="网络构图"
             android:textSize="15sp" />

         <com.example.hellojni.SlideSwitch
             android:id="@+id/slideSwitch1"
             android:layout_width="116dip"
             android:layout_height="46dip"
             android:layout_alignParentRight="true"
             android:layout_centerVertical="true" />
     </RelativeLayout>

     <RelativeLayout
         android:layout_width="fill_parent"
         android:layout_height="wrap_content" >

         <TextView
             android:id="@+id/textView2"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:layout_alignParentLeft="true"
             android:layout_centerVertical="true"
             android:text="保留原图"
             android:textSize="15sp" />

         <com.example.hellojni.SlideSwitch
             android:id="@+id/slideSwitch2"
             android:layout_width="116dip"
             android:layout_height="46dip"
             android:layout_alignParentRight="true"
             android:layout_centerVertical="true" />
     </RelativeLayout>

     <RelativeLayout
         android:layout_width="fill_parent"
         android:layout_height="wrap_content" >

         <TextView
             android:id="@+id/textView3"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:layout_alignParentLeft="true"
             android:layout_centerVertical="true"
             android:text="拍照声音"
             android:textSize="15sp" />

         <com.example.hellojni.SlideSwitch
             android:id="@+id/slideSwitch3"
             android:layout_width="116px"
             android:layout_height="46px"
             android:layout_alignParentRight="true"
             android:layout_centerVertical="true" />
     </RelativeLayout>

     <TextView
         android:id="@+id/textViewTip"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:gravity="center"
         android:text="TextView" />