android.support.v7.widget.StaggeredGridLayoutManager#findFirstCompletelyVisibleItemPositions ( )源码实例Demo

下面列出了android.support.v7.widget.StaggeredGridLayoutManager#findFirstCompletelyVisibleItemPositions ( ) 实例代码，或者点击链接到github查看源代码，也可以在右侧发表评论。

源代码1 项目： HeaderFooterRecyclerView 文件： OnRecyclerViewScrollListener.java

/**
 * 计算第一个元素的位置
 */
private int calculateFirstVisibleItemPos(RecyclerView.LayoutManager layoutManager, int firstVisibleItemPosition) {
    switch (mLayoutManagerType) {
        case LINEAR:
            mLastVisibleItemPosition = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();
            firstVisibleItemPosition = ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();
            break;
        case GRID:
            mLastVisibleItemPosition = ((GridLayoutManager) layoutManager).findLastVisibleItemPosition();
            firstVisibleItemPosition = ((GridLayoutManager) layoutManager).findFirstVisibleItemPosition();
            break;
        case STAGGERED_GRID:
            StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
            if (mLastPositions == null) {
                mLastPositions = new int[staggeredGridLayoutManager.getSpanCount()];
            }
            mLastPositions = staggeredGridLayoutManager.findLastVisibleItemPositions(mLastPositions);
            mLastVisibleItemPosition = findMax(mLastPositions);
            staggeredGridLayoutManager.findFirstCompletelyVisibleItemPositions(mLastPositions);
            firstVisibleItemPosition = findMax(mLastPositions);
            break;
    }
    return firstVisibleItemPosition;
}

源代码2 项目： AndroidBase 文件： FamiliarRecyclerView.java

public int getFirstVisiblePosition() {
    LayoutManager layoutManager = getLayoutManager();

    if (null == layoutManager)
        return 0;

    int ret = -1;

    switch (mLayoutManagerType) {
        case LAYOUT_MANAGER_TYPE_LINEAR:
            ret = ((LinearLayoutManager) layoutManager).findFirstCompletelyVisibleItemPosition() - getHeaderViewsCount();
            break;
        case LAYOUT_MANAGER_TYPE_GRID:
            ret = ((GridLayoutManager) layoutManager).findFirstCompletelyVisibleItemPosition() - getHeaderViewsCount();
            break;
        case LAYOUT_MANAGER_TYPE_STAGGERED_GRID:
            StaggeredGridLayoutManager tempStaggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
            int[] firstVisibleItemPositions = new int[tempStaggeredGridLayoutManager.getSpanCount()];
            tempStaggeredGridLayoutManager.findFirstCompletelyVisibleItemPositions(firstVisibleItemPositions);
            ret = firstVisibleItemPositions[0] - getHeaderViewsCount();
            break;
    }

    return ret < 0 ? 0 : ret;
}

源代码3 项目： CommonAdapter 文件： OnRcvScrollListener.java

/**
 * 计算第一个元素的位置
 */
private int calculateFirstVisibleItemPos(int type, RecyclerView.LayoutManager layoutManager, int firstVisibleItemPosition) {
    switch (type) {
        case TYPE_LINEAR:
            mLastVisibleItemPosition = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();
            firstVisibleItemPosition = ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();
            break;
        case TYPE_GRID:
            mLastVisibleItemPosition = ((GridLayoutManager) layoutManager).findLastVisibleItemPosition();
            firstVisibleItemPosition = ((GridLayoutManager) layoutManager).findFirstVisibleItemPosition();
            break;
        case TYPE_STAGGERED_GRID:
            StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
            if (mLastPositions == null) {
                mLastPositions = new int[staggeredGridLayoutManager.getSpanCount()];
            }
            mLastPositions = staggeredGridLayoutManager.findLastVisibleItemPositions(mLastPositions);
            mLastVisibleItemPosition = findMax(mLastPositions);
            staggeredGridLayoutManager.findFirstCompletelyVisibleItemPositions(mLastPositions);
            firstVisibleItemPosition = findMax(mLastPositions);
            break;
    }
    return firstVisibleItemPosition;
}

源代码4 项目： ExRecyclerView 文件： OnRecyclerViewScrollListener.java

/**
 * 计算第一个元素的位置
 */
private int calculateFirstVisibleItemPos(RecyclerView.LayoutManager layoutManager, int firstVisibleItemPosition) {
    switch (mLayoutManagerType) {
        case LINEAR:
            mLastVisibleItemPosition = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();
            firstVisibleItemPosition = ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();
            break;
        case GRID:
            mLastVisibleItemPosition = ((GridLayoutManager) layoutManager).findLastVisibleItemPosition();
            firstVisibleItemPosition = ((GridLayoutManager) layoutManager).findFirstVisibleItemPosition();
            break;
        case STAGGERED_GRID:
            StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
            if (mLastPositions == null) {
                mLastPositions = new int[staggeredGridLayoutManager.getSpanCount()];
            }
            mLastPositions = staggeredGridLayoutManager.findLastVisibleItemPositions(mLastPositions);
            mLastVisibleItemPosition = findMax(mLastPositions);
            staggeredGridLayoutManager.findFirstCompletelyVisibleItemPositions(mLastPositions);
            firstVisibleItemPosition = findMax(mLastPositions);
            break;
    }
    return firstVisibleItemPosition;
}

源代码5 项目： JD-Test 文件： PtrDefaultHandler.java

public static boolean canChildScrollUp(View view) {
    if (android.os.Build.VERSION.SDK_INT < 14) {
        if (view instanceof AbsListView) {
            final AbsListView absListView = (AbsListView) view;
            return absListView.getChildCount() > 0
                    && (absListView.getFirstVisiblePosition() > 0 || absListView.getChildAt(0)
                    .getTop() < absListView.getPaddingTop());
        } else if(view instanceof  RecyclerView){
            RecyclerView recyclerView = (RecyclerView)view;
            RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
            if(layoutManager instanceof LinearLayoutManager){
                int position = ((LinearLayoutManager) layoutManager).findFirstCompletelyVisibleItemPosition();
                return position != 0;
            }else{
                if(layoutManager instanceof StaggeredGridLayoutManager ){
                    StaggeredGridLayoutManager stagger = (StaggeredGridLayoutManager) layoutManager;
                    int[] positions = stagger.findFirstCompletelyVisibleItemPositions(null);
                    return positions[0] != 0;
                }else{
                    throw new RuntimeException("can not support this LayoutManager ");
                }
            }
        }else{
            return view.getScrollY() > 0;
        }
    } else {
        return view.canScrollVertically(-1);
    }
}

源代码6 项目： ht-refreshrecyclerview 文件： Utils.java

/**
 * 获取第一个可见/完全可见item的位置索引
 * @param layoutManager       RecyclerView.LayoutManager对象
 * @param isCompletelyVisible 是否完全可见
 * @return item的索引
 */
public static int getFirstItemPosition(@NonNull RecyclerView.LayoutManager layoutManager, boolean isCompletelyVisible) {
    int firstVisibleItemPosition = -1;
    if (layoutManager instanceof LinearLayoutManager) { //GridLayoutManager继承LinearLayoutManager
        LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
        firstVisibleItemPosition = isCompletelyVisible ? linearLayoutManager.findFirstCompletelyVisibleItemPosition() : linearLayoutManager.findFirstVisibleItemPosition();
    } else if (layoutManager instanceof StaggeredGridLayoutManager) {
        StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
        int[] firstVisibleItemPositions = isCompletelyVisible ? staggeredGridLayoutManager.findFirstCompletelyVisibleItemPositions(null) : staggeredGridLayoutManager.findFirstVisibleItemPositions(null);
        if (firstVisibleItemPositions != null && firstVisibleItemPositions.length > 0)
            firstVisibleItemPosition = firstVisibleItemPositions[0];
    }
    return firstVisibleItemPosition;
}

源代码7 项目： Bounce 文件： BounceTouchListener.java

private boolean hasHitTop() {
    if (mMainView instanceof ScrollView) {
        ScrollView scrollView = (ScrollView) mMainView;
        return scrollView.getScrollY() == 0;
    } else if (mMainView instanceof ListView) {
        ListView listView = (ListView) mMainView;
        if (listView.getAdapter() != null) {
            if (listView.getAdapter().getCount() > 0) {
                return listView.getFirstVisiblePosition() == 0 &&
                        listView.getChildAt(0).getTop() >= 0;
            }
        }
    } else if (mMainView instanceof RecyclerView) {
        RecyclerView recyclerView = (RecyclerView) mMainView;
        if (recyclerView.getAdapter() != null && recyclerView.getLayoutManager() != null) {
            RecyclerView.Adapter adapter = recyclerView.getAdapter();
            if (adapter.getItemCount() > 0) {
                RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
                if (layoutManager instanceof LinearLayoutManager) {
                    LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
                    return linearLayoutManager.findFirstCompletelyVisibleItemPosition() == 0;
                } else if (layoutManager instanceof StaggeredGridLayoutManager) {
                    StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
                    int[] checks = staggeredGridLayoutManager.findFirstCompletelyVisibleItemPositions(null);
                    for (int check : checks) {
                        if (check == 0)
                            return true;
                    }
                }
            }
        }
    }

    return false;
}

源代码8 项目： LRecyclerView 文件： LRecyclerView.java

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

    int firstVisibleItemPosition = 0;
    RecyclerView.LayoutManager layoutManager = getLayoutManager();

    if (layoutManagerType == null) {
        if (layoutManager instanceof LinearLayoutManager) {
            layoutManagerType = LayoutManagerType.LinearLayout;
        } else if (layoutManager instanceof GridLayoutManager) {
            layoutManagerType = LayoutManagerType.GridLayout;
        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
            layoutManagerType = LayoutManagerType.StaggeredGridLayout;
        } else {
            throw new RuntimeException(
                    "Unsupported LayoutManager used. Valid ones are LinearLayoutManager, GridLayoutManager and StaggeredGridLayoutManager");
        }
    }

    switch (layoutManagerType) {
        case LinearLayout:
            firstVisibleItemPosition = ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();
            lastVisibleItemPosition = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();
            break;
        case GridLayout:
            firstVisibleItemPosition = ((GridLayoutManager) layoutManager).findFirstVisibleItemPosition();
            lastVisibleItemPosition = ((GridLayoutManager) layoutManager).findLastVisibleItemPosition();
            break;
        case StaggeredGridLayout:
            StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
            if (lastPositions == null) {
                lastPositions = new int[staggeredGridLayoutManager.getSpanCount()];
            }
            staggeredGridLayoutManager.findLastVisibleItemPositions(lastPositions);
            lastVisibleItemPosition = findMax(lastPositions);
            staggeredGridLayoutManager.findFirstCompletelyVisibleItemPositions(lastPositions);
            firstVisibleItemPosition = findMax(lastPositions);
            break;
        default:
            break;
    }

    // 根据类型来计算出第一个可见的item的位置，由此判断是否触发到底部的监听器
    // 计算并判断当前是向上滑动还是向下滑动
    calculateScrollUpOrDown(firstVisibleItemPosition, dy);
    // 移动距离超过一定的范围，我们监听就没有啥实际的意义了
    mScrolledXDistance += dx;
    mScrolledYDistance += dy;
    mScrolledXDistance = (mScrolledXDistance < 0) ? 0 : mScrolledXDistance;
    mScrolledYDistance = (mScrolledYDistance < 0) ? 0 : mScrolledYDistance;
    if (mIsScrollDown && (dy == 0)) {
        mScrolledYDistance = 0;
    }
    //Be careful in here
    if (null != mLScrollListener) {
        mLScrollListener.onScrolled(mScrolledXDistance, mScrolledYDistance);
    }

    if (mLoadMoreListener != null && mLoadMoreEnabled) {
        int visibleItemCount = layoutManager.getChildCount();
        int totalItemCount = layoutManager.getItemCount();
        if (visibleItemCount > 0
                && lastVisibleItemPosition >= totalItemCount - 1
                && (isCritical ? totalItemCount >= visibleItemCount : totalItemCount > visibleItemCount)
                && !isNoMore
                && !mRefreshing) {

            mFootView.setVisibility(View.VISIBLE);
            if (!mLoadingData) {
                mLoadingData = true;
                mLoadMoreFooter.onLoading();
                mLoadMoreListener.onLoadMore();
            }

        }

    }
    if (isOnTop() && dy > 0 && mRefreshHeader.getType() == IRefreshHeader.TYPE_HEADER_MATERIAL && !mRefreshing && (appbarState
        == AppBarStateChangeListener.State.EXPANDED)) {
        mRefreshHeader.onMove(dy, mScrolledYDistance);
    }
}

源代码9 项目： LRecyclerView 文件： LuRecyclerView.java

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

    int firstVisibleItemPosition = 0;
    RecyclerView.LayoutManager layoutManager = getLayoutManager();

    if (layoutManagerType == null) {
        if (layoutManager instanceof LinearLayoutManager) {
            layoutManagerType = LayoutManagerType.LinearLayout;
        } else if (layoutManager instanceof GridLayoutManager) {
            layoutManagerType = LayoutManagerType.GridLayout;
        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
            layoutManagerType = LayoutManagerType.StaggeredGridLayout;
        } else {
            throw new RuntimeException(
                    "Unsupported LayoutManager used. Valid ones are LinearLayoutManager, GridLayoutManager and StaggeredGridLayoutManager");
        }
    }

    switch (layoutManagerType) {
        case LinearLayout:
            firstVisibleItemPosition = ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();
            lastVisibleItemPosition = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();
            break;
        case GridLayout:
            firstVisibleItemPosition = ((GridLayoutManager) layoutManager).findFirstVisibleItemPosition();
            lastVisibleItemPosition = ((GridLayoutManager) layoutManager).findLastVisibleItemPosition();
            break;
        case StaggeredGridLayout:
            StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
            if (lastPositions == null) {
                lastPositions = new int[staggeredGridLayoutManager.getSpanCount()];
            }
            staggeredGridLayoutManager.findLastVisibleItemPositions(lastPositions);
            lastVisibleItemPosition = findMax(lastPositions);
            staggeredGridLayoutManager.findFirstCompletelyVisibleItemPositions(lastPositions);
            firstVisibleItemPosition = findMax(lastPositions);
            break;
        default:
            break;
    }

    // 根据类型来计算出第一个可见的item的位置，由此判断是否触发到底部的监听器
    // 计算并判断当前是向上滑动还是向下滑动
    calculateScrollUpOrDown(firstVisibleItemPosition, dy);
    // 移动距离超过一定的范围，我们监听就没有啥实际的意义了
    mScrolledXDistance += dx;
    mScrolledYDistance += dy;
    mScrolledXDistance = (mScrolledXDistance < 0) ? 0 : mScrolledXDistance;
    mScrolledYDistance = (mScrolledYDistance < 0) ? 0 : mScrolledYDistance;
    if (mIsScrollDown && (dy == 0)) {
        mScrolledYDistance = 0;
    }
    //Be careful in here
    if (null != mLScrollListener) {
        mLScrollListener.onScrolled(mScrolledXDistance, mScrolledYDistance);
    }

    //如果想要滑动到底部自动加载更多，mIsManualLoadMore必须为false
    if (mIsManualLoadMore) {
        if (!isNoMore) {
            Log.e("lzx","onScrooo set visible");
            mLoadingData = true;
            mLoadMoreFooter.setOnClickLoadMoreListener(mLoadMoreListener);
        }

    } else {
        if (mLoadMoreListener != null && mLoadMoreEnabled) {
            int visibleItemCount = layoutManager.getChildCount();
            int totalItemCount = layoutManager.getItemCount();
            if (visibleItemCount > 0
                    && lastVisibleItemPosition >= totalItemCount - 1
                    && (isCritical ? totalItemCount >= visibleItemCount : totalItemCount > visibleItemCount)
                    && !isNoMore
                    && !mRefreshing) {

                mFootView.setVisibility(View.VISIBLE);
                if (!mLoadingData) {
                    mLoadingData = true;
                    mLoadMoreFooter.onLoading();
                    mLoadMoreListener.onLoadMore();
                }

            }

        }
    }

}

方法所在类

android.support.v7.widget.StaggeredGridLayoutManager