自定义Switch控件

package com.easyway.widget;



import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.ImageView;
/**
 * 
 * 
 * @Title: 
 * @Description: 实现TODO
 * @Copyright:Copyright (c) 2011
 * @Company:易程科技股份有限公司
 * @Date:2012-8-17
 * @author  longgangbai
 * @version 1.0
 */
public class Switch extends ImageView {
    private static final String TAG = "Switch";
    private static final int TEXT_SIZE = 12;
    private OnCheckedChangeListener mOnCheckedChangeListener;
    private boolean mChecked;
    private Paint mPaint;
    private String mCheckedString, mUnCheckedString;
    public interface OnCheckedChangeListener {
        public void onCheckedChanged(Switch switchView, boolean isChecked);
    }

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

    public Switch(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public Switch(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        // init desity dpi，之前引用屏幕密度的时候出现问题，去掉密度，按实际的宽和高的比例来设置文字的位置
//        DisplayMetrics metric = new DisplayMetrics();
//        WindowManager windowManager = (WindowManager) context
//                .getSystemService(Context.WINDOW_SERVICE);
//        windowManager.getDefaultDisplay().getMetrics(metric);
//        mDensity = metric.density;
        mCheckedString = context.getResources().getString(R.string.switch_on);//业务功能开启时的图片显示文字字符串：即ON
        mUnCheckedString = context.getResources().getString(R.string.switch_off);//OFF
        setBackgroundResource(R.drawable.white_btn);//设置开关按钮的背景
        setChecked(false);//初始化控件为关的状态
        configPaint();//设置画布属性（去掉密度，直接以字体12显示）
       // computePosition();
    }

  // private void computePosition() {
//        mLeftTextX = LEFT_STATE_STRING_MARGIN_LEFT * mDensity;
//        mRightTextX = RIGHT_STATE_STRING_MARGIN_LEFT * mDensity;
//        mTextY = STRING_MARGIN_TOP * mDensity;
    	//modify by chengxi
//      mLeftTextX = getWidth()/2/3 * mDensity;
//      mRightTextX =getWidth()/2* mDensity;
//      mTextY = STRING_MARGIN_TOP * mDensity; 	
 //   }

    private void configPaint() {
        mPaint = new Paint();
        mPaint.setAntiAlias(true);//去文字锯齿
      //  mPaint.setTextSize(TEXT_SIZE * mDensity);
        mPaint.setTextSize(TEXT_SIZE);
        mPaint.setColor(Color.WHITE);//画布背景即文字字体的颜色
    }

    public void setChecked(boolean checked) {
        mChecked = checked;
        if (mChecked) {
            setImageResource(R.drawable.on_btn);
        } else {
            setImageResource(R.drawable.off_btn);
        }
        postInvalidate();
            //见http://blog.csdn.net/sdhjob/article/details/6512973
            //View的invalidate和postInvalidate都是更新界面，不同的是
            //invalidate与创建VIEW都是在同一个线程中执行的，即主线程，如果在非主线程中执行的话需要配合Handler使用
            //而postInvalidate可以在非主线程中更新UI界面

    }

    public boolean isChecked() {
        return mChecked;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (mChecked) {
            // draw checked
        //	canvas.drawText(mCheckedString, (getWidth()*0.6f), getHeight()*0.7f, mPaint);
        } else { 
            // draw unchecked
        //	canvas.drawText(mUnCheckedString, getWidth()*0.1f , getHeight()*0.7f, mPaint);
        }
    //画VIEW的时候开始画的点(0,0)是在左上角，图片从左上往下画，画文字的时候开始画的点是在左下角，文字从左下往上画
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        int action = event.getAction();
        switch (action) {
            case MotionEvent.ACTION_UP:
                setChecked(!mChecked);
                if (mOnCheckedChangeListener != null) {
                    mOnCheckedChangeListener.onCheckedChanged(this, mChecked);
                }
                break;
            default:
                // Do nothing
                break;
        }

        return true;
    }

    public void setOnCheckedChangeListener(OnCheckedChangeListener listener) {
        mOnCheckedChangeListener = listener;
    }

}

布局文件：

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_height="wrap_content" 
    android:layout_width="wrap_content" 
    android:orientation="vertical"
    android:id="@+id/dialog">  

    <com.easyway.widget.Switch
        android:id="@+id/switch1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/white_btn" />

    <TextView
           android:layout_width="wrap_content"
        android:layout_height="12sp"
         />
    <com.easyway.widget.Switch
        android:id="@+id/switch2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:src="@drawable/white_btn" />
  
</LinearLayout>  

代码如下：