可移动带分割线的GridView（空白项有分割线）

/**
 *
 *
 *
 * 可以拖动，带分割线的GridView
 *
 */
@SuppressLint("NewApi")
public class DragGridView extends GridView {
   /**
    * DragGridView的item长按响应的时间， 默认是1000毫秒，也可以自行设置
    */
   private long dragResponseMS = 1000;

   /**
    * 是否可以拖拽，默认不可以
    */
   private boolean isDrag = false;

   private int mDownX;
   private int mDownY;
   private int moveX;
   private int moveY;
   /**
    * 正在拖拽的position
    */
   private int mDragPosition;

   /**
    * 刚开始拖拽的item对应的View
    */
   private View mStartDragItemView = null;

   /**
    * 用于拖拽的镜像，这里直接用一个ImageView
    */
   private ImageView mDragImageView;

   /**
    * 震动器
    */
   private Vibrator mVibrator;

   private WindowManager mWindowManager;
   /**
    * item镜像的布局参数
    */
   private WindowManager.LayoutParams mWindowLayoutParams;

   /**
    * 我们拖拽的item对应的Bitmap
    */
   private Bitmap mDragBitmap;

   /**
    * 按下的点到所在item的上边缘的距离
    */
   private int mPoint2ItemTop ;

   /**
    * 按下的点到所在item的左边缘的距离
    */
   private int mPoint2ItemLeft;

   /**
    * DragGridView距离屏幕顶部的偏移量
    */
   private int mOffset2Top;

   /**
    * DragGridView距离屏幕左边的偏移量
    */
   private int mOffset2Left;

   /**
    * 状态栏的高度
    */
   private int mStatusHeight;

   /**
    * DragGridView自动向下滚动的边界值
    */
   private int mDownScrollBorder;

   /**
    * DragGridView自动向上滚动的边界值
    */
   private int mUpScrollBorder;

   /**
    * DragGridView自动滚动的速度
    */
   private static final int speed = 80;

   /**
    * item发生变化回调的接口
    */
   private OnChanageListener onChanageListener;



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

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

   public DragGridView(Context context, AttributeSet attrs, int defStyle) {
      super(context, attrs, defStyle);
      mVibrator = (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE);
      mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
      mStatusHeight = getStatusHeight(context); //获取状态栏的高度
   }

   private Handler mHandler = new Handler();

   //用来处理是否为长按的Runnable
   private Runnable mLongClickRunnable = new Runnable() {

      @Override
      public void run() {
         isDrag = true; //设置可以拖拽
         mVibrator.vibrate(50); //震动一下
         mStartDragItemView.setVisibility(View.INVISIBLE);//隐藏该item

         //根据我们按下的点显示item镜像
         createDragImage(mDragBitmap, mDownX, mDownY);
      }
   };

   /**
    * 设置回调接口
    * @param onChanageListener
    */
   public void setOnChangeListener(OnChanageListener onChanageListener){
      this.onChanageListener = onChanageListener;
   }

   /**
    * 设置响应拖拽的毫秒数，默认是1000毫秒
    * @param dragResponseMS
    */
   public void setDragResponseMS(long dragResponseMS) {
      this.dragResponseMS = dragResponseMS;
   }

   @Override
   public boolean dispatchTouchEvent(MotionEvent ev) {
      switch(ev.getAction()){
         case MotionEvent.ACTION_DOWN:
            //使用Handler延迟dragResponseMS执行mLongClickRunnable
            mHandler.postDelayed(mLongClickRunnable, dragResponseMS);

            mDownX = (int) ev.getX();
            mDownY = (int) ev.getY();

            //根据按下的X,Y坐标获取所点击item的position
            mDragPosition = pointToPosition(mDownX, mDownY);

            if(mDragPosition == AdapterView.INVALID_POSITION){
               return super.dispatchTouchEvent(ev);
            }

            //根据position获取该item所对应的View
            mStartDragItemView = getChildAt(mDragPosition - getFirstVisiblePosition());

            //下面这几个距离大家可以参考我的博客上面的图来理解下
            mPoint2ItemTop = mDownY - mStartDragItemView.getTop();
            mPoint2ItemLeft = mDownX - mStartDragItemView.getLeft();

            mOffset2Top = (int) (ev.getRawY() - mDownY);
            mOffset2Left = (int) (ev.getRawX() - mDownX);

            //获取DragGridView自动向上滚动的偏移量，小于这个值，DragGridView向下滚动
            mDownScrollBorder = getHeight() /4;
            //获取DragGridView自动向下滚动的偏移量，大于这个值，DragGridView向上滚动
            mUpScrollBorder = getHeight() * 3/4;



            //开启mDragItemView绘图缓存
            mStartDragItemView.setDrawingCacheEnabled(true);
            //获取mDragItemView在缓存中的Bitmap对象
            mDragBitmap = Bitmap.createBitmap(mStartDragItemView.getDrawingCache());
            //这一步很关键，释放绘图缓存，避免出现重复的镜像
            mStartDragItemView.destroyDrawingCache();


            break;
         case MotionEvent.ACTION_MOVE:
            int moveX = (int)ev.getX();
            int moveY = (int) ev.getY();

            //如果我们在按下的item上面移动，只要不超过item的边界我们就不移除mRunnable
            if(!isTouchInItem(mStartDragItemView, moveX, moveY)){
               mHandler.removeCallbacks(mLongClickRunnable);
            }
            break;
         case MotionEvent.ACTION_UP:
            mHandler.removeCallbacks(mLongClickRunnable);
            mHandler.removeCallbacks(mScrollRunnable);
            break;
      }
      return super.dispatchTouchEvent(ev);
   }


   /**
    * 是否点击在GridView的item上面
    * @param
    * @param x
    * @param y
    * @return
    */
   private boolean isTouchInItem(View dragView, int x, int y){
      if(dragView==null){
         return false;
      }
      int leftOffset = dragView.getLeft();
      int topOffset = dragView.getTop();
      if(x < leftOffset || x > leftOffset + dragView.getWidth()){
         return false;
      }

      if(y < topOffset || y > topOffset + dragView.getHeight()){
         return false;
      }

      return true;
   }



   @Override
   public boolean onTouchEvent(MotionEvent ev) {
      if(isDrag && mDragImageView != null){
         switch(ev.getAction()){
            case MotionEvent.ACTION_MOVE:
               moveX = (int) ev.getX();
               moveY = (int) ev.getY();
               //拖动item
               onDragItem(moveX, moveY);
               break;
            case MotionEvent.ACTION_UP:
               onStopDrag();
               isDrag = false;
               break;
         }
         return true;
      }
      return super.onTouchEvent(ev);
   }


   /**
    * 创建拖动的镜像
    * @param bitmap
    * @param downX
    *           按下的点相对父控件的X坐标
    * @param downY
    *           按下的点相对父控件的X坐标
    */
   private void createDragImage(Bitmap bitmap, int downX , int downY){
      mWindowLayoutParams = new WindowManager.LayoutParams();
      mWindowLayoutParams.format = PixelFormat.TRANSLUCENT; //图片之外的其他地方透明
      mWindowLayoutParams.gravity = Gravity.TOP | Gravity.LEFT;
      mWindowLayoutParams.x = downX - mPoint2ItemLeft + mOffset2Left;
      mWindowLayoutParams.y = downY - mPoint2ItemTop + mOffset2Top - mStatusHeight;
      mWindowLayoutParams.alpha = 0.55f; //透明度
      mWindowLayoutParams.width = WindowManager.LayoutParams.WRAP_CONTENT;
      mWindowLayoutParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
      mWindowLayoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
            | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE ;

      mDragImageView = new ImageView(getContext());
      mDragImageView.setImageBitmap(bitmap);
      mWindowManager.addView(mDragImageView, mWindowLayoutParams);
   }

   /**
    * 从界面上面移动拖动镜像
    */
   private void removeDragImage(){
      if(mDragImageView != null){
         mWindowManager.removeView(mDragImageView);
         mDragImageView = null;
      }
   }

   /**
    * 拖动item，在里面实现了item镜像的位置更新，item的相互交换以及GridView的自行滚动
    * @param
    * @param
    */
   private void onDragItem(int moveX, int moveY){
      mWindowLayoutParams.x = moveX - mPoint2ItemLeft + mOffset2Left;
      mWindowLayoutParams.y = moveY - mPoint2ItemTop + mOffset2Top - mStatusHeight;
      mWindowManager.updateViewLayout(mDragImageView, mWindowLayoutParams); //更新镜像的位置
      onSwapItem(moveX, moveY);

      //GridView自动滚动
      mHandler.post(mScrollRunnable);
   }


   /**
    * 当moveY的值大于向上滚动的边界值，触发GridView自动向上滚动
    * 当moveY的值小于向下滚动的边界值，触犯GridView自动向下滚动
    * 否则不进行滚动
    */
   private Runnable mScrollRunnable = new Runnable() {

      @Override
      public void run() {
         int scrollY;
         if(moveY > mUpScrollBorder){
            scrollY = -speed;
            mHandler.postDelayed(mScrollRunnable, 25);
         }else if(moveY < mDownScrollBorder){
            scrollY = speed;
            mHandler.postDelayed(mScrollRunnable, 25);
         }else{
            scrollY = 0;
            mHandler.removeCallbacks(mScrollRunnable);
         }

         //当我们的手指到达GridView向上或者向下滚动的偏移量的时候，可能我们手指没有移动，但是DragGridView在自动的滚动
         //所以我们在这里调用下onSwapItem()方法来交换item
         onSwapItem(moveX, moveY);

         View view = getChildAt(mDragPosition - getFirstVisiblePosition());
         //实现GridView的自动滚动
         smoothScrollToPositionFromTop(mDragPosition, view.getTop() + scrollY);
      }
   };


   /**
    * 交换item,并且控制item之间的显示与隐藏效果
    * @param moveX
    * @param moveY
    */
   private void onSwapItem(int moveX, int moveY){
      //获取我们手指移动到的那个item的position
      int tempPosition = pointToPosition(moveX, moveY);

      //假如tempPosition 改变了并且tempPosition不等于-1,则进行交换
      if(tempPosition != mDragPosition && tempPosition != AdapterView.INVALID_POSITION){
         getChildAt(tempPosition - getFirstVisiblePosition()).setVisibility(View.INVISIBLE);//拖动到了新的item,新的item隐藏掉
         getChildAt(mDragPosition - getFirstVisiblePosition()).setVisibility(View.VISIBLE);//之前的item显示出来

         if(onChanageListener != null){
            onChanageListener.onChange(mDragPosition, tempPosition);
         }

         mDragPosition = tempPosition;
      }
   }


   /**
    * 停止拖拽我们将之前隐藏的item显示出来，并将镜像移除
    */
   private void onStopDrag(){
      getChildAt(mDragPosition - getFirstVisiblePosition()).setVisibility(View.VISIBLE);
      removeDragImage();
   }

   /**
    * 获取状态栏的高度
    * @param context
    * @return
    */
   private static int getStatusHeight(Context context){
      int statusHeight = 0;
      Rect localRect = new Rect();
      ((Activity) context).getWindow().getDecorView().getWindowVisibleDisplayFrame(localRect);
      statusHeight = localRect.top;
      if (0 == statusHeight){
         Class<?> localClass;
         try {
            localClass = Class.forName("com.android.internal.R$dimen");
            Object localObject = localClass.newInstance();
            int i5 = Integer.parseInt(localClass.getField("status_bar_height").get(localObject).toString());
            statusHeight = context.getResources().getDimensionPixelSize(i5);
         } catch (Exception e) {
            e.printStackTrace();
         }
      }
      return statusHeight;
   }


   /**
    *
    *
    *
    */
   public interface OnChanageListener{

      /**
       * 当item交换位置的时候回调的方法，我们只需要在该方法中实现数据的交换即可
       * @param form
       *           开始的position
       * @param to
       *           拖拽到的position
       */
      public void onChange(int form, int to);
   }


//空白项有分割线
@Override
protected void dispatchDraw(Canvas canvas){
   super.dispatchDraw(canvas);
   try {
      View localView1 = getChildAt(0);
      int column = getWidth() / localView1.getWidth();
      int childCount = getChildCount();
      Paint localPaint;
      localPaint = new Paint();
      localPaint.setStyle(Paint.Style.STROKE);
      localPaint.setColor(getContext().getResources().getColor(R.color.diverline));



      for(int i = 0;i < childCount;i++){
         View cellView = getChildAt(i);
         if((i + 1) % column == 0){
            canvas.drawLine(cellView.getLeft(), cellView.getBottom(), cellView.getRight(), cellView.getBottom(), localPaint);
         }else if((i + 1) > (childCount - (childCount % column))){
            canvas.drawLine(cellView.getRight(), cellView.getTop(), cellView.getRight(), cellView.getBottom(), localPaint);
         }else{
            canvas.drawLine(cellView.getRight(), cellView.getTop(), cellView.getRight(), cellView.getBottom(), localPaint);
            canvas.drawLine(cellView.getLeft(), cellView.getBottom(), cellView.getRight(), cellView.getBottom(), localPaint);
         }
      }
      if(childCount % column != 0){
         for(int j = 0 ;j < (column-childCount % column) ; j++){
            View lastView = getChildAt(childCount - 1);
            canvas.drawLine(lastView.getRight() + lastView.getWidth() * j, lastView.getTop(), lastView.getRight() + lastView.getWidth()* j, lastView.getBottom(), localPaint);
         }
      }
   }catch (Exception e){

   }
}
//空白项无分割线
// @Override
// protected void dispatchDraw(Canvas canvas) {
//    //分割线处理
//    super.dispatchDraw(canvas);
//    View localView1 = getChildAt(0);
//    int column = getWidth() / localView1.getWidth();//列数
//    int childCount = getChildCount();
//    Paint localPaint;
//    localPaint = new Paint();
//    localPaint.setStyle(Paint.Style.STROKE);
//    localPaint.setColor(getContext().getResources().getColor(R.color.diverline));//这个就是设置分割线的颜色
//    for (int i = 0; i < childCount; i++) {
//       View cellView = getChildAt(i);
//       if ((i + 1) % column == 0) {//每一行最后一个
//          canvas.drawLine(cellView.getLeft(), cellView.getBottom(), cellView.getRight(), cellView.getBottom(), localPaint);
////         } else if ((i + 1) > (childCount - (childCount % column))) {//最后一行的item
////            canvas.drawLine(cellView.getRight(), cellView.getTop(), cellView.getRight(), cellView.getBottom(), localPaint);
//       } else {
//          canvas.drawLine(cellView.getRight(), cellView.getTop(), cellView.getRight(), cellView.getBottom(), localPaint);
//          canvas.drawLine(cellView.getLeft(), cellView.getBottom(), cellView.getRight(), cellView.getBottom(), localPaint);
//       }
//    }
// }

}