Android GridView 拖拽Item及滚屏实现，针对以前修改的，进行了再修改。
这次就能很好的实现了长按，然后向下拖动，背景的Item也向上的效果。
注要对如下函数进行了修改：
private void onDrag(int x, int y) { if (dragImageView != null) { windowParams.alpha = 0.6f; windowParams.x = x - dragPointX + dragOffsetX; windowParams.y = y - dragPointY + dragOffsetY; // L.l("=================windowParams.y=====000========"+windowParams.y); windowManager.updateViewLayout(dragImageView, windowParams); } int tempScrollX = x - dragPointX + dragOffsetX; int tempScrollY = y - dragPointY + dragOffsetY; int rangeY = itemHeight; int maxHeight = getHeight() - rangeY; int position = pointToPosition(x, y); int gridViewCount = this.getCount(); int allContainCount = gridViewCount; int leftCount = gridViewCount % numColumns; if (leftCount != 0) { allContainCount += (numColumns - leftCount); } int upMaxPosition = allContainCount - numColumns; L.l("==========position:" + position + " max:" + upMaxPosition + " count:" + this.getChildCount() + " rangy:" + rangeY); // 如果position大于最大的item if (position >= upMaxPosition || position < numColumns) { L.l("=====last line=======postion:" + position); setEnabled(false); } else { L.l("=====good========tempScrollY: " + tempScrollY + " rangeY:" + rangeY + " maxHeight:" + maxHeight); if (tempScrollY < rangeY)// 假如漂浮的view已经进入第一行,则把当前的gridView滑出一个 { L.l("=====gridView scroll down=======:" + tempScrollY); setEnabled(true); int position2 = getFirstVisiblePosition(); smoothScrollToPosition(position2 - 1); // scrollTo(0, -itemHeight); } else if (tempScrollY > maxHeight) { L.l("=====gridView scroll up=======:" + tempScrollY); setEnabled(true); int position1 = getLastVisiblePosition(); smoothScrollToPosition(position1 + 1); // scrollTo(0, itemHeight); } } }自此完全搞定Item拖拽。