android上相仿iphone上的开关按钮

public class SlipButton extends View {        private boolean nowChoose = false;//记录当前按钮是否打开,true为打开,flase为关闭      private boolean onSlip = false;//记录用户是否在滑动的变量      private float nowX;//按下时的x,当前的x    private float downX;    private float baseX;    private OnChangedListener ChgLsn;      private Bitmap slip_btn;     private float centerX;        private float yes_text_width;    private float no_text_width;        private int btnWdith;    private String[] messages;        private Paint paint;          public SlipButton(Context context) {          super(context);           init();      }        public SlipButton(Context context, AttributeSet attrs) {          super(context, attrs);          init();      }        private void init() {         paint = new Paint();        paint.setAntiAlias(true);        paint.setColor(Color.BLACK);        paint.setTextSize(14);        setMessages(new String[]{"Yes", "No"});    }        public void setButtonBitmap(Bitmap bitmap) {    	if (bitmap == null) {    		return;    	}    	slip_btn = bitmap;        btnWdith = slip_btn.getWidth() / 3;        centerX = btnWdith / 2;    }        public void setTextColor(int color) {    	paint.setColor(color);    }        public void setTextSize(int size) {    	paint.setTextSize(size);    }        public void setMessages(String[] messages) {    	this.messages = messages;    	yes_text_width = paint.measureText(messages[0]);        no_text_width = paint.measureText(messages[1]);    }        public void setStatusOn(boolean on) {    	nowChoose = on;    }        public boolean getStatusOn() {    	return nowChoose;    }        public void setOnChangedListener(OnChangedListener l) {        ChgLsn = l;      }          @Override      protected void onDraw(Canvas canvas) {         super.onDraw(canvas);        if (slip_btn == null) {    		return;    	}                float minX = centerX;        float maxX = getMeasuredWidth() - centerX;                if (onSlip) {        	nowX = baseX - (downX - nowX);        	nowX = Math.min(Math.max(minX, nowX), maxX);        } else {        	if (nowChoose) {        		nowX = maxX;        	} else {        		nowX = minX;        	}        	baseX = nowX;        }	    canvas.drawBitmap(slip_btn, nowX - centerX - btnWdith, 0, paint);//画出游标.	           int marginX1 = (int)(btnWdith - yes_text_width) / 2;        canvas.drawText(messages[0], nowX - centerX - marginX1 - yes_text_width, 22, paint);	            int marginX2 = (int)(btnWdith - no_text_width) / 2;        canvas.drawText(messages[1], nowX + centerX + marginX2, 22, paint);    }          @Override	public boolean onTouchEvent(MotionEvent event) {    	if (slip_btn == null) {    		return false;    	}    	        switch(event.getAction())//根据动作来执行代码          {          case MotionEvent.ACTION_MOVE://滑动         	nowX = event.getX();        	float moveX = downX - nowX;        	if (Math.abs(moveX) > 5) {        		onSlip = true;        	}            break;          case MotionEvent.ACTION_DOWN://按下          	downX = event.getX();            break;          case MotionEvent.ACTION_UP://松开          	boolean LastChoose = nowChoose;        	if (onSlip) {        		moveX = downX - event.getX();        		if (nowChoose) {        			if ((moveX > 0) && (moveX >= centerX))        				nowChoose = !nowChoose;        		} else {        			if ((moveX < 0) && (Math.abs(moveX) >= centerX))        				nowChoose = !nowChoose;        		}         	} else {        		nowChoose = !nowChoose;        	}            onSlip = false;            if ((ChgLsn != null) && (LastChoose != nowChoose)) {            	if (nowChoose) {            		ChgLsn.onChanged(nowChoose, messages[0]);            	} else {            		ChgLsn.onChanged(nowChoose, messages[1]);            	}            }            break;          default:        	break;         }          invalidate();//重画控件          return true;	}        public interface OnChangedListener {    	public void onChanged(boolean on, String value);    }}