Android自定义View实现拖动选择按钮

public class CircleView extends View {
 /**
  * 默认颜色
  */
 private final int DEFAULT_COLOR = Color.LTGRAY;
 /**
  * 默认半径dp
  */
 private final float DEFAULT_RADIUS = 32;
 private int mColor;
 private Paint mCirclePaint;
 private float mRadius;
 private float mCenterX;
 private float mCenterY;

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

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

 public CircleView(Context context, AttributeSet attrs, int defStyleAttr)
 {
  super(context, attrs, defStyleAttr);
  TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.DragView);
  mColor = array.getColor(R.styleable.DragView_color_circle,DEFAULT_COLOR);
  mCirclePaint = new Paint();
  mCirclePaint.setColor(mColor);

  mCenterY = mCenterX = mRadius = getMeasuredWidth() == 0&＃63;DEFAULT_RADIUS:getMeasuredWidth()/2;
  array.recycle();
 }

 public float getRadius(){
  return mRadius;
 }

 public int getColor()
 {
  return mColor;
 }

 @Override
 protected void onDraw(Canvas canvas)
 {
  canvas.drawCircle(mCenterX,mCenterY,mRadius,mCirclePaint);
 }
}

public class DragView extends RelativeLayout implements View.OnTouchListener {

 private Drawable mDragIcon;//拖动图标
 private ImageView mDragView;//拖动图标ImageView
 private int mCircleColor;//圆的颜色
 private Context mContext;//上下文
 private int mDotNum;//节点数量

 private int mWidth;//组件的宽度
 private int mHight;//组件的高度
 private int mCircleRadius;//园的半径
 private int mDragWidth;//拖动图标的宽度
 private int mLineWidth,mLineHeight;//中间线的长宽

 private float mStartX;//开始拖动的屏幕坐标
 private float mCurX;//开始拖动的触点坐标
 private float mMinX;//拖动范围的最小值
 private float mMaxX;//拖动范围的最大值

 private OnNodeSelect mOnNodeSelect;//回调接口

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

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

 public DragView(Context context, AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);
  TypedArray array=context.obtainStyledAttributes(attrs, R.styleable.DragView);
  mDragIcon=array.getDrawable(R.styleable.DragView_icon_drag);
  mCircleColor=array.getColor(R.styleable.DragView_color_circle,Color.WHITE);
  mDotNum=array.getInt(R.styleable.DragView_dot_num,2);
  array.recycle();
  mCOntext=context;
  initView();
 }

 /**
  *视图初始化，这个方法的作用是把所有的视图添加进来，并做一些初始化的配置
  * 其实可以用LayoutInflater把xml的布局文件加载进来，这样比较简便
  */
 public void initView(){
  for (int i=0;i= 0 && x <= mMaxX - mMinX) {
      v.setTranslationX(mCurX + event.getRawX() - mStartX);
     }

     break;

    case MotionEvent.ACTION_UP:
    case MotionEvent.ACTION_CANCEL:

     int distance=(int) (event.getRawX()-mStartX);
     if (distance>0){
      if (Math.abs(distance)>mLineWidth/2){
       v.setTranslationX(mCurX + event.getRawX() - mStartX);
       setAnim(mLineWidth,1);
      }else {
       v.setTranslationX(mCurX + event.getRawX() - mStartX);
       setAnim(0,0);
      }
     }else if (distance<0){
      if (Math.abs(distance)>mLineWidth/2){
       v.setTranslationX(mCurX + event.getRawX() - mStartX);
       setAnim(0,0);
      }else {
       v.setTranslationX(mCurX + event.getRawX() - mStartX);
       setAnim(mLineWidth,1);
      }
     }

     break;
   }
  }else if (v instanceof CircleView){
   switch (event.getAction()) {
    case MotionEvent.ACTION_UP:
     if (event.getRawX()>getDisplayWidth()/2){
      setAnim(mLineWidth,1);
     }else {
      setAnim(0,0);
     }
     break;
   }
  }
  return true;
 }

 //设置平移动画
 private void setAnim(float moveX, final int scrollPosition) {
  ObjectAnimator animator = ObjectAnimator.ofFloat(mDragView, "translationX", mDragView.getTranslationX(), moveX);
  animator.setDuration(300);
  animator.start();
  if (mOnNodeSelect != null) {
   mOnNodeSelect.onNodeSelect(scrollPosition);
  }
 }

 public void setNodeSelectListener(OnNodeSelect onNodeSelect) {
  mOnNodeSelect= onNodeSelect;
 }

 //事件回调接口
 public interface OnNodeSelect {
  void onNodeSelect(int position);
 }

 //dp转px
 public int dp2px(Context context, float dpValue)
 {
  final float scale = context.getResources().getDisplayMetrics().density;
  return (int) (dpValue * scale + 0.5f);
 }

 //获取屏幕宽度
 public int getDisplayWidth(){
  DisplayMetrics metrics=new DisplayMetrics();
  ((Activity)mContext).getWindowManager().getDefaultDisplay().getMetrics(metrics);
  return metrics.widthPixels;
 }
}

 dragView=(DragView)view.findViewById(R.id.view_drag);
 dragView.setNodeSelectListener(new DragView.OnNodeSelect() {
  @Override
  public void onNodeSelect(int position) {
   Toast.makeText(getActivity(),"我选择了"+position,Toast.LENGTH_SHORT).show();
  }
 });