SlipButton——滑动开关

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import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;

/**
 * 滑动开关
 * 备注：解决初始状态bug --1130
 */
public class SlipButton extends View implements OnTouchListener
{

    private boolean IsOpen;//记录当前button是否打开,true为打开,flase为关闭 做了点改动
    private boolean OnSlip = false;//记录用户是否在滑动的变量
    private float DownX, NowX;//按下时的x,当前的x,
    private Rect Btn_On, Btn_Off;//打开和关闭状态下,游标的Rect
    private boolean isChgLsnOn = false;
    private OnChangedListener chgLsn;
    private Bitmap bg_on, bg_off, slip_btn;

    public SlipButton(Context context)
    {
        super(context);

        init();
    }

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

        init();
    }

    private void init()
    {//初始化
     //加载图片资源  

        bg_on = BitmapFactory.decodeResource(getResources(),
                R.drawable.split_left_1);
        bg_off = BitmapFactory.decodeResource(getResources(),
                R.drawable.split_right_1);
        slip_btn = BitmapFactory.decodeResource(getResources(),
                R.drawable.split_1);
        Btn_On = new Rect(0, 0, slip_btn.getWidth(), slip_btn.getHeight());
        Btn_Off = new Rect(bg_off.getWidth() - slip_btn.getWidth(), 0,
                bg_off.getWidth(), slip_btn.getHeight());
        setOnTouchListener(this);// 设置监听器,也能够直接复写OnTouchEvent
    }

    @Override
    protected void onDraw(Canvas canvas)
    {
        //画图函数
        super.onDraw(canvas);

        Matrix matrix = new Matrix();
        Paint paint = new Paint();
        float x;

        //依据设置推断初始状态
        if (IsOpen)
        {
            NowX = bg_on.getWidth();
        }
        else
        {
            NowX = 0;
        }
        {
            if (NowX < (bg_on.getWidth() / 2))//滑动到前半段与后半段的背景不同,在此做推断
            {
                canvas.drawBitmap(bg_off, matrix, paint);//画出关闭时的背景
            }
            else
            {
                canvas.drawBitmap(bg_on, matrix, paint);//画出打开时的背景
            }

            if (OnSlip)//是否是在滑动状态,
            {
                if (NowX >= bg_on.getWidth())//是否划出指定范围,不能让游标跑到外头,必须做这个推断
                {
                    x = bg_on.getWidth() - slip_btn.getWidth() / 2;//减去游标1/2的长度...
                }

                else
                {
                    x = NowX - slip_btn.getWidth() / 2;
                }
            }
            else
            {//非滑动状态
                if (IsOpen)//依据如今的开关状态设置画游标的位置
                {
                    x = Btn_Off.left;
                }
                else
                {
                    x = Btn_On.left;
                }
            }
            if (x < 0)//对游标位置进行异常推断...
            {
                x = 0;
            }
            else if (x > bg_on.getWidth() - slip_btn.getWidth())
            {
                x = bg_on.getWidth() - slip_btn.getWidth();
            }

            canvas.drawBitmap(slip_btn, x, 0, paint);//画出游标.
        }
    }

    @Override
    public boolean onTouch(View v, MotionEvent event)
    {
        switch (event.getAction())
        //依据动作来运行代码
        {
            case MotionEvent.ACTION_MOVE://滑动  

                NowX = event.getX();
                break;
            case MotionEvent.ACTION_DOWN://按下  

                if (event.getX() > bg_on.getWidth()
                        || event.getY() > bg_on.getHeight())
                {
                    return false;
                }

                OnSlip = true;
                DownX = event.getX();
                NowX = DownX;
                break;
            case MotionEvent.ACTION_UP://松开  

                OnSlip = false;
                boolean LastChoose = IsOpen;
                if (event.getX() >= (bg_on.getWidth() / 2))
                {
                    IsOpen = true;
                }
                else
                {
                    IsOpen = false;
                }

                if (isChgLsnOn && (LastChoose != IsOpen))//假设设置了监听器,就调用其方法..
                {
                    chgLsn.onChanged(IsOpen, this);
                }
                break;
            default:

        }

        invalidate();//重画控件
        return true;
    }

    public void setOnChangedListener(OnChangedListener l)
    {//设置监听器,当状态改动的时候
        isChgLsnOn = true;
        chgLsn = l;
    }

    public void setCheck(boolean isCheck)
    {
        IsOpen = isCheck;
        invalidate();
    }

    public interface OnChangedListener
    {
        abstract void onChanged(boolean checkState, View v);
    }
}