Java Code Examples for android.support.v7.widget.RecyclerView#getLayoutManager()

public void onMoved(RecyclerView recyclerView, ViewHolder viewHolder, int fromPos, ViewHolder target, int toPos, int x, int y) {
    LayoutManager layoutManager = recyclerView.getLayoutManager();
    if (layoutManager instanceof ViewDropHandler) {
        ((ViewDropHandler) layoutManager).prepareForDrop(viewHolder.itemView, target.itemView, x, y);
        return;
    }
    if (layoutManager.canScrollHorizontally()) {
        if (layoutManager.getDecoratedLeft(target.itemView) <= recyclerView.getPaddingLeft()) {
            recyclerView.scrollToPosition(toPos);
        }
        if (layoutManager.getDecoratedRight(target.itemView) >= recyclerView.getWidth() - recyclerView.getPaddingRight()) {
            recyclerView.scrollToPosition(toPos);
        }
    }
    if (layoutManager.canScrollVertically()) {
        if (layoutManager.getDecoratedTop(target.itemView) <= recyclerView.getPaddingTop()) {
            recyclerView.scrollToPosition(toPos);
        }
        if (layoutManager.getDecoratedBottom(target.itemView) >= recyclerView.getHeight() - recyclerView.getPaddingBottom()) {
            recyclerView.scrollToPosition(toPos);
        }
    }
}
 

@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
    mInnerAdapter.onAttachedToRecyclerView(recyclerView);
    super.onAttachedToRecyclerView(recyclerView);
    //对Grid布局进行支持
    RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();
    if (manager instanceof GridLayoutManager) {
        final GridLayoutManager gridLayoutManager = (GridLayoutManager) manager;
        final GridLayoutManager.SpanSizeLookup origin = gridLayoutManager.getSpanSizeLookup();
        gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                if (isLoadMoreView(position)) {
                    return gridLayoutManager.getSpanCount();
                } else {
                    if (origin != null) {
                        return origin.getSpanSize(position);
                    } else return 1;
                }
            }
        });
    }
}
 

private int getSpanCount(RecyclerView parent)
{
    // 列数
    int spanCount = -1;
    LayoutManager layoutManager = parent.getLayoutManager();
    if (layoutManager instanceof GridLayoutManager)
    {

        spanCount = ((GridLayoutManager) layoutManager).getSpanCount();
    } else if (layoutManager instanceof StaggeredGridLayoutManager)
    {
        spanCount = ((StaggeredGridLayoutManager) layoutManager)
                .getSpanCount();
    }
    return spanCount;
}
 

private void updateRecyclerViewScrollState(RecyclerView recyclerView) {
    if (recyclerView.getChildCount() == 0) {
        setDraggable(true);
    } else {
        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
        int[] i = new int[1];
        if (layoutManager instanceof LinearLayoutManager || layoutManager instanceof GridLayoutManager) {
            i[0] = ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();
        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
            i = null;
            i = ((StaggeredGridLayoutManager) layoutManager).findFirstVisibleItemPositions(i);
        }
        if (i[0] == 0) {
            View firstChild = recyclerView.getChildAt(0);
            if (firstChild.getTop() == recyclerView.getPaddingTop()) {
                setDraggable(true);
                return;
            }
        }
        setDraggable(false);
    }
}
 

@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
  super.onScrollStateChanged(recyclerView, newState);
  currentScrollState = newState;
  RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
  int visibleItemCount = layoutManager.getChildCount();
  int totalItemCount = layoutManager.getItemCount();

  if (visibleItemCount != 0) {
    int bottomOffset = (totalItemCount - lastVisibleItemPosition - 1) * (recyclerView.getHeight()) / visibleItemCount;
    if (visibleItemCount > 0 && currentScrollState == RecyclerView.SCROLL_STATE_IDLE) {
      if (listener != null && listener.get() != null) {
        listener.get().onLoadMore(bottomOffset);
      }
    }
  }
}
 

private boolean isLastColum(RecyclerView parent, int pos, int spanCount,
                            int childCount) {
    RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
    if (layoutManager instanceof GridLayoutManager) {
        if ((pos + 1) % spanCount == 0)// 如果是最后一列，则不需要绘制右边
        {
            return true;
        }
    } else if (layoutManager instanceof StaggeredGridLayoutManager) {
        int orientation = ((StaggeredGridLayoutManager) layoutManager)
                .getOrientation();
        if (orientation == StaggeredGridLayoutManager.VERTICAL) {
            if ((pos + 1) % spanCount == 0)// 如果是最后一列，则不需要绘制右边
            {
                return true;
            }
        } else {
            childCount = childCount - childCount % spanCount;
            if (pos >= childCount)// 如果是最后一列，则不需要绘制右边
                return true;
        }
    }
    return false;
}
 

@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
    super.onAttachedToRecyclerView(recyclerView);
    mRecyclerView = recyclerView;

    //Grid的 Header Footer 宽度处理
    RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();
    if (manager instanceof GridLayoutManager) {
        final GridLayoutManager gridManager = ((GridLayoutManager) manager);
        gridManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                boolean isData = dataSet.data.is(position);
                if (isData) {
                    return 1;
                } else {
                    return gridManager.getSpanCount();
                }
            }
        });
    }
}
 

/**
 * 这个方法是与recyclerView绑定
 * @param recyclerView                      recyclerView
 * @throws IllegalStateException
 */
@Override
public void attachToRecyclerView(@Nullable RecyclerView recyclerView)
        throws IllegalStateException {
    if (recyclerView != null && !(recyclerView.getLayoutManager()
            instanceof LinearLayoutManager)) {
        throw new IllegalStateException("ScrollPageHelper needs a " +
                "RecyclerView with a LinearLayoutManager");
    }
    if (recyclerView != null) {
        //设置fling监听为null
        recyclerView.setOnFlingListener(null);
        if ((gravity == Gravity.START || gravity == Gravity.END)) {
            isRtlHorizontal = isRtl();
        }
    }
    super.attachToRecyclerView(recyclerView);
}
 

private int getSpanCount(RecyclerView parent) {
    // 列数
    int spanCount = -1;
    LayoutManager layoutManager = parent.getLayoutManager();
    if (layoutManager instanceof GridLayoutManager) {

        spanCount = ((GridLayoutManager) layoutManager).getSpanCount();
    } else if (layoutManager instanceof StaggeredGridLayoutManager) {
        spanCount = ((StaggeredGridLayoutManager) layoutManager)
                .getSpanCount();
    }
    return spanCount;
}
 

/**
 * get total Span Count
 *
 * @param parent
 * @return
 */
int getSpanCount(RecyclerView parent) {
    int spanCount = -1;
    RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
    if (layoutManager instanceof GridLayoutManager) {
        spanCount = ((GridLayoutManager) layoutManager).getSpanCount();
    } else if (layoutManager instanceof StaggeredGridLayoutManager) {
        spanCount = ((StaggeredGridLayoutManager) layoutManager).getSpanCount();
    }
    return spanCount;
}
 

@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
    super.onScrollStateChanged(recyclerView, newState);
    currentScrollState = newState;
    RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
    int visibleItemCount = layoutManager.getChildCount();
    int totalItemCount = layoutManager.getItemCount();
    if ((visibleItemCount > 0 && currentScrollState == RecyclerView.SCROLL_STATE_IDLE && (lastVisibleItemPosition) >= totalItemCount - 1) && mSuperRefreshLayout.isLoadMore()) {
        mSuperRefreshLayout.loadMore();
    }
}
 

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
    super.getItemOffsets(outRect, view, parent, state);
    int pos = parent.getChildAdapterPosition(view);
    RecyclerView.LayoutManager manager = parent.getLayoutManager();
    if (manager instanceof GridLayoutManager) {
        //网格布局
        int spanCount = ((GridLayoutManager) manager).getSpanCount();
        if (isFirstLineInGroup(pos, spanCount)) {
            //为悬浮view预留空间
            outRect.top = mGroupHeight;
        } else {
            //为分割线预留空间
            outRect.top = mDivideHeight;
        }
    } else {
        //其他的默认为线性布局
        //只有是同一组的第一个才显示悬浮栏
        if (isFirstInGroup(pos)) {
            //为悬浮view预留空间
            outRect.top = mGroupHeight;
        } else {
            //为分割线预留空间
            outRect.top = mDivideHeight;
        }
    }
}
 

protected LinearLayoutManager getLinearLayoutManger(RecyclerView parent) {
    RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
    if (layoutManager instanceof LinearLayoutManager) {
        return (LinearLayoutManager) layoutManager;
    }
    return null;
}
 

@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {

    RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();

    //RecycleView 显示的条目数
    int visibleCount = layoutManager.getChildCount();
    Log.d(TAG, "onScrollStateChanged: visibleCount = " + visibleCount);

    //显示数据总数
    int totalCount = layoutManager.getItemCount();
    Log.d(TAG, "onScrollStateChanged: totalCount = " + totalCount);

    Log.d(TAG, "onScrollStateChanged: lastVisibleItemPosition = " + mLastVisibleItemPosition);

    // 四个条件，分别是是否有数据，状态是否是滑动停止状态，显示的最大条目是否大于整个数据（注意偏移量），是否正在加载数据
    if(visibleCount>0
            &&newState==RecyclerView.SCROLL_STATE_IDLE
            &&mLastVisibleItemPosition>=totalCount-1
            &&!isLoadData){
        //可以加载数据
        if(mListener!=null){
            isLoadData = true;
            mListener.loadMore();
        }
    }else{
        Log.d(TAG, "onScrollStateChanged: no data");
    }

}
 

/**
 * Determines whether divider was already drawn for the row the item is in,
 * effectively only makes sense for a grid
 *
 * @param position current view position to draw divider
 * @param parent   RecyclerView
 * @return true if the divider can be skipped as it is in the same row as the previous one.
 */
private boolean wasDividerAlreadyDrawn(int position, RecyclerView parent) {
    if (parent.getLayoutManager() instanceof GridLayoutManager) {
        GridLayoutManager layoutManager = (GridLayoutManager) parent.getLayoutManager();
        GridLayoutManager.SpanSizeLookup spanSizeLookup = layoutManager.getSpanSizeLookup();
        int spanCount = layoutManager.getSpanCount();
        return spanSizeLookup.getSpanIndex(position, spanCount) > 0;
    }

    return false;
}
 

public X8LocalFragmentPresenter(RecyclerView mRecyclerView, X8sPanelRecycleAdapter mPanelRecycleAdapter, ISelectData mISelectData, Context context) {
    super(mRecyclerView, mPanelRecycleAdapter, mISelectData, context, false);
    doTrans();
    LayoutManager manager = mRecyclerView.getLayoutManager();
    if (manager instanceof GridLayoutManager) {
        this.mGridLayoutManager = (GridLayoutManager) manager;
    }
    registerReciver();
}
 

@Override
public int onDragFlags(RecyclerView recyclerView, RecyclerView.ViewHolder targetViewHolder) {
    int adapterPosition = targetViewHolder.getAdapterPosition();
    if (adapterPosition == 0) { // 这里让HeaderView不能拖拽。
        return OnItemMovementListener.INVALID;// 返回无效的方向。
    }

    // 真实的Position：通过ViewHolder拿到的position都需要减掉HeadView的数量。
    int position = adapterPosition - mRecyclerView.getHeaderItemCount();

    // 假如让普通Item的第一个不能拖拽。
    if (position == 0) {
        return OnItemMovementListener.INVALID;// 返回无效的方向。
    }

    RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
    if (layoutManager instanceof GridLayoutManager) {
        // Grid可以上下左右拖拽。
        return OnItemMovementListener.LEFT |
                OnItemMovementListener.UP |
                OnItemMovementListener.RIGHT |
                OnItemMovementListener.DOWN;
    } else if (layoutManager instanceof LinearLayoutManager) {
        LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;

        // 横向List只能左右拖拽。
        if (linearLayoutManager.getOrientation() == LinearLayoutManager.HORIZONTAL) {
            return (OnItemMovementListener.LEFT | OnItemMovementListener.RIGHT);
        }
        // 竖向List只能上下拖拽。
        else {
            return OnItemMovementListener.UP | OnItemMovementListener.DOWN;
        }
    }
    return OnItemMovementListener.INVALID;// 返回无效的方向。
}
 

@Override
public void getItemOffsets(final Rect outRect, final View view, final RecyclerView parent, RecyclerView.State state) {

    checkCache(parent);

    if (!mEnableDivider) {
        return;
    }

    if (mDrawable == null) {
        mDrawable = ContextCompat.getDrawable(parent.getContext(), mDividerId != 0 ? mDividerId : R.drawable.divider);
    }

    if (parent.getLayoutManager() instanceof GridLayoutManager) {
        if (!isPinnedHeader(parent, view)) {
            final int spanCount = getSpanCount(parent);
            int position = parent.getChildAdapterPosition(view);
            if (isFirstColumn(parent, position, spanCount)) {
                // 第一列要多画左边
                outRect.set(mDrawable.getIntrinsicWidth(), 0, mDrawable.getIntrinsicWidth(), mDrawable.getIntrinsicHeight());
            } else {
                outRect.set(0, 0, mDrawable.getIntrinsicWidth(), mDrawable.getIntrinsicHeight());
            }
        } else {
            // 标签画底部分隔线
            outRect.set(0, 0, 0, mDrawable.getIntrinsicHeight());
        }
    } else if (parent.getLayoutManager() instanceof LinearLayoutManager) {
        outRect.set(0, 0, 0, mDrawable.getIntrinsicHeight());
    } else if (parent.getLayoutManager() instanceof StaggeredGridLayoutManager) {
        if (isPinnedHeader(parent, view)) {
            outRect.set(0, 0, 0, mDrawable.getIntrinsicHeight());
        } else {
            final StaggeredGridLayoutManager.LayoutParams slp = (StaggeredGridLayoutManager.LayoutParams) view.getLayoutParams();
            // slp.getSpanIndex(): 这个可以拿到它在同一行排序的真实顺序
            if (slp.getSpanIndex() == 0) {
                outRect.set(mDrawable.getIntrinsicWidth(), 0, mDrawable.getIntrinsicWidth(), mDrawable.getIntrinsicHeight());
            } else {
                outRect.set(0, 0, mDrawable.getIntrinsicWidth(), mDrawable.getIntrinsicHeight());
            }
        }
    }
}
 

@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
    super.onScrolled(recyclerView, dx, dy);

    RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
    if (layoutManagerType == null) {
        if (layoutManager instanceof LinearLayoutManager) {
            layoutManagerType = LAYOUT_MANAGER_TYPE.LINEAR;
        } else if (layoutManager instanceof GridLayoutManager) {
            layoutManagerType = LAYOUT_MANAGER_TYPE.GRID;
        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
            layoutManagerType = LAYOUT_MANAGER_TYPE.STAGGERED_GRID;
        } else {
            throw new RuntimeException("Unsupported");
        }
    }

    switch (layoutManagerType) {
        case LINEAR:
            lastVisibleItemPosition = ((LinearLayoutManager) layoutManager)
                    .findLastVisibleItemPosition();

            firstVisibleItemPosition = ((LinearLayoutManager) layoutManager)
                    .findFirstVisibleItemPosition();
            break;
        case GRID:
            lastVisibleItemPosition = ((GridLayoutManager) layoutManager)
                    .findLastVisibleItemPosition();
            firstVisibleItemPosition = ((GridLayoutManager) layoutManager)
                    .findFirstVisibleItemPosition();
            break;
        case STAGGERED_GRID:
            StaggeredGridLayoutManager staggeredGridLayoutManager
                    = (StaggeredGridLayoutManager) layoutManager;
            if (lastPositions == null) {
                lastPositions = new int[staggeredGridLayoutManager.getSpanCount()];
            }
            if (firstPositions == null) {
                firstPositions = new int[staggeredGridLayoutManager.getSpanCount()];
            }
            staggeredGridLayoutManager.findLastVisibleItemPositions(lastPositions);
            staggeredGridLayoutManager.findFirstVisibleItemPositions(firstPositions);
            lastVisibleItemPosition = findMax(lastPositions);
            firstVisibleItemPosition = findMin(firstPositions);
            break;
    }
    onScrolled(firstVisibleItemPosition);


}
 

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
    outRect.left = space;
    outRect.right = space;
    outRect.bottom = space;

    // Add top margin only for the first item to avoid double space between items

    if(parent.getLayoutManager() instanceof GridLayoutManager){

        int colcount = ((GridLayoutManager) parent.getLayoutManager()).getSpanCount();

        if(parent.getChildPosition(view) < colcount){
            outRect.top = space;
        }

    }else if(parent.getChildPosition(view) == 0){
        outRect.top = space;
    }



}