Android自定义View实现可以拖拽的GridView

public class DragGridVeiw extends GridView {  private final int PRESS_TIME = 1000;//长按时间  private int mDownX;//触碰时的X坐标  private int mDownY;//触碰时的Y坐标  private int mMoveX;//移动时的X坐标  private int mMoveY;//移动时的Y坐标  private int mOffset2Top;//DragGridView距离屏幕顶部的偏移量  private int mOffset2Left;//DragGridView距离屏幕左边的偏移量  private int mPointToItemTop;//触碰点距离ItemView的上边距  private int mPointToItemLeft;//触碰点距离ItemView的左边距  private int mStatusHeight;//状态栏高度  private boolean isDraging;//是否正在拖曳  private Bitmap mBitmap;//ItemView的图片  private int mTouchPostiion;//触碰的位置  private View mTouchItemView;//触碰的ItemView  private Vibrator mVibrator;//震动器  private ImageView mDragImageView;//拖曳的View  private WindowManager mWindowManager;//窗口管理器  private WindowManager.LayoutParams mWindowLayoutParams;//窗口管理器布局  private OnChanageListener onChanageListener;//交换事件监听器  private Handler mHandler = new Handler();  public DragGridVeiw(Context context) {    this(context, null);  }  public DragGridVeiw(Context context, AttributeSet attrs) {    this(context, attrs, 0);  }  public DragGridVeiw(Context context, AttributeSet attrs, int defStyleAttr) {    super(context, attrs, defStyleAttr);    mStatusHeight = getStatusHeight(context);    mVibrator = (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE);    mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);  }  @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, PRESS_TIME);        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        mTouchPostiion = pointToPosition(mDownX, mDownY);        if (mTouchPostiion == AdapterView.INVALID_POSITION) {          return super.dispatchTouchEvent(ev);        }        //根据position获取该item所对应的View        mTouchItemView = getChildAt(mTouchPostiion - 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        mPointToItemTop = mDownY - mTouchItemView.getTop();        mPointToItemLeft = mDownX - mTouchItemView.getLeft();        mOffset2Top = (int) (ev.getRawY() - mDownY);        mOffset2Left = (int) (ev.getRawX() - mDownX);        //开启mDragItemView绘图缓存        mTouchItemView.setDrawingCacheEnabled(true);        //获取mDragItemView在缓存中的Bitmap对象        mBitmap = Bitmap.createBitmap(mTouchItemView.getDrawingCache());        //这一步很关键，释放绘图缓存，避免出现重复的镜像        mTouchItemView.destroyDrawingCache();        break;      case MotionEvent.ACTION_MOVE:        int moveX = (int) ev.getX();        int moveY = (int) ev.getY();        //拖曳点超出GridView区域则取消拖曳事件        if (ev.getY() > getHeight() || ev.getY() < 0) {          onStopDrag();        }        //如果我们在按下的item上面移动，只要超过item的边界就移除mRunnable        if (!isTouchInItem(mTouchItemView, moveX, moveY)) {          mHandler.removeCallbacks(mLongClickRunnable);        }        break;      case MotionEvent.ACTION_UP:        mHandler.removeCallbacks(mLongClickRunnable);        break;    }    return super.dispatchTouchEvent(ev);  }  @Override  public boolean onTouchEvent(MotionEvent ev) {    if (isDraging && mDragImageView != null) {      switch (ev.getAction()) {        case MotionEvent.ACTION_MOVE:          mMoveX = (int) ev.getX();          mMoveY = (int) ev.getY();          //拖动item          onDragItem(mMoveX, mMoveY);          break;        case MotionEvent.ACTION_UP:          onStopDrag();          break;      }      return true;    }    return super.onTouchEvent(ev);  }  //处理长按事件的线程  private Runnable mLongClickRunnable = new Runnable() {    @Override    public void run() {      isDraging = true; //设置可以拖拽      mVibrator.vibrate(50); //震动一下      mTouchItemView.setVisibility(View.INVISIBLE);//隐藏该ItemView      //根据我们按下的点显示ItemView镜像      createDragView(mBitmap, mDownX, mDownY);    }  };  //添加拖动View  private void createDragView(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 - mPointToItemTop + mOffset2Left;    mWindowLayoutParams.y = downY - mPointToItemTop + mOffset2Top - mStatusHeight;    mWindowLayoutParams.alpha = 0.6f; //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);  }  private void removeDragView() {    if (mDragImageView != null) {      mWindowManager.removeView(mDragImageView);      mDragImageView = null;    }  }  //是否点击在GridView的item上面  private boolean isTouchInItem(View dragView, int x, int y) {    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;  }  //拖动事件处理  private void onDragItem(int moveX, int moveY) {    mWindowLayoutParams.x = moveX - mPointToItemLeft + mOffset2Left;    mWindowLayoutParams.y = moveY - mPointToItemTop + mOffset2Top - mStatusHeight;    mWindowManager.updateViewLayout(mDragImageView, mWindowLayoutParams); //更新DragView的位置    onSwapItem(moveX, moveY);//Item的相互交换  }  //交换item,并且控制item之间的显示与隐藏效果  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 != mTouchPostiion && tempPosition != AdapterView.INVALID_POSITION) {      getChildAt(tempPosition - getFirstVisiblePosition()).setVisibility(View.INVISIBLE);//拖动到了新的item,新的item隐藏掉      getChildAt(mTouchPostiion - getFirstVisiblePosition()).setVisibility(View.VISIBLE);//之前的item显示出来      if (onChanageListener != null) {        onChanageListener.onChange(mTouchPostiion, tempPosition);      }      mTouchPostiion = tempPosition;    }  }  //停止拖拽我们将之前隐藏的item显示出来，并将DragView移除  private void onStopDrag() {    isDraging = false;    getChildAt(mTouchPostiion - getFirstVisiblePosition()).setVisibility(View.VISIBLE);    removeDragView();  }  //Item交换事件监听  public void setOnChangeListener(OnChanageListener onChanageListener) {    this.onChanageListener = onChanageListener;  }  //获取状态栏高度  private 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;  }  //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  public interface OnChanageListener {    public void onChange(int from, int to);  }}

   List<HashMap<String, Object>> dataSourceList = new ArrayList<>();    dragVeiw = (DragGridVeiw) findViewById(R.id.view_drag);    for (int i = 0; i < 8; i++) {      HashMap<String, Object> itemHashMap = new HashMap<>();      itemHashMap.put("item_image", R.drawable.sample_1);      itemHashMap.put("item_text", "拖拽 " + Integer.toString(i));      dataSourceList.add(itemHashMap);    }    final SimpleAdapter mSimpleAdapter = new SimpleAdapter(this, dataSourceList,        R.layout.item_drag, new String[]{"item_image", "item_text"},        new int[]{R.id.item_image, R.id.item_text});    dragVeiw.setAdapter(mSimpleAdapter);    dragVeiw.setOnChangeListener(new DragGridVeiw.OnChanageListener() {      @Override      public void onChange(int from, int to) {        HashMap<String, Object> temp = dataSourceList.get(from);        //这里的处理需要注意下        if (from < to) {          for (int i = from; i < to; i++) {            Collections.swap(dataSourceList, i, i + 1);          }        } else if (from > to) {          for (int i = from; i > to; i--) {            Collections.swap(dataSourceList, i, i - 1);          }        }        dataSourceList.set(to, temp);        mSimpleAdapter.notifyDataSetChanged();      }    });

Log.v("-->getWidth", String.valueOf(getWidth()));//DragView的宽度Log.v("-->getHeight", String.valueOf(getHeight()));//DragView的高度Log.v("-->getLeft", String.valueOf(getLeft()));//DragView左边距离屏幕左侧的长度Log.v("-->getTop", String.valueOf(getTop()));///DragView上边距离屏幕顶部的长度Log.v("-->getRawX", String.valueOf(ev.getRawX()));//触碰点相对于屏幕的X坐标Log.v("-->getRawY", String.valueOf(ev.getRawY()));//触碰点相对于屏幕的Y坐标Log.v("-->getX", String.valueOf(ev.getX()));//触碰点相对于DragView的X坐标Log.v("-->getY", String.valueOf(ev.getY()));//触碰点相对于DragView的Y坐标Log.v("-->getItemWidth", String.valueOf(mTouchItemView.getWidth()));//DragView中ItemView的宽度Log.v("-->getItemHeight", String.valueOf(mTouchItemView.getHeight()));//DragView中ItemView的高度Log.v("-->getItemLeft", String.valueOf(mTouchItemView.getLeft()));//DragView中ItemView左边距离DragView左侧的长度Log.v("-->getItemTop", String.valueOf(mTouchItemView.getTop()));//DragView中ItemView上边距离DragView顶部的长度