Java Code Examples for android.support.v7.widget.RecyclerView#LayoutManager

@Override
public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY,
    int actionState, boolean isCurrentlyActive) {
    // 判断当前是否是swipe方式：侧滑。
    if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {
        //1.ItemView--ViewHolder; 2.侧滑条目的透明度程度关联谁？dX(delta增量，范围：当前条目-width~width)。
        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
        float alpha = 1;
        if (layoutManager instanceof LinearLayoutManager) {
            int orientation = ((LinearLayoutManager)layoutManager).getOrientation();
            if (orientation == LinearLayoutManager.HORIZONTAL) {
                alpha = 1 - Math.abs(dY) / viewHolder.itemView.getHeight();
            } else if (orientation == LinearLayoutManager.VERTICAL) {
                alpha = 1 - Math.abs(dX) / viewHolder.itemView.getWidth();
            }
        }
        viewHolder.itemView.setAlpha(alpha);//1~0
    }
    super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
}
 

@Nullable
@Override
public int[] calculateDistanceToFinalSnap(@NonNull RecyclerView.LayoutManager layoutManager, @NonNull View targetView) {
    int[] out = new int[2];
    if (layoutManager.canScrollHorizontally()) {
        if (gravity == Gravity.START) {
            out[0] = distanceToStart(targetView, getHorizontalHelper(layoutManager), false);
        } else { // END
            out[0] = distanceToEnd(targetView, getHorizontalHelper(layoutManager), false);
        }
    } else {
        out[0] = 0;
    }
    if (layoutManager.canScrollVertically()) {
        if (gravity == Gravity.TOP) {
            out[1] = distanceToStart(targetView, getVerticalHelper(layoutManager), false);
        } else { // BOTTOM
            out[1] = distanceToEnd(targetView, getVerticalHelper(layoutManager), false);
        }
    } else {
        out[1] = 0;
    }
    return out;
}
 

/**
 * 获取指定区域item的高度
 **/
public int getItemsHeight(int start, int end) {
    int height = 0;
    if (start > end || end > datas.size() - 1) {
        return height;
    }
    start = start < 0 ? 0 : start;
    RecyclerView.LayoutManager layoutManager = mListFragment.getLayoutManager();
    for (int i = start; i <= end; i++) {
        View item = layoutManager.findViewByPosition(i);
        if (item != null) {
            ViewGroup.MarginLayoutParams layoutParams = (ViewGroup.MarginLayoutParams) item.getLayoutParams();
            height += item.getHeight() + item.getPaddingBottom() + item.getPaddingTop() + layoutParams.topMargin + layoutParams.bottomMargin /*item.getBottom() - item.getTop()*/;
                /*int desiredWidth = View.MeasureSpec.makeMeasureSpec(item.getWidth(), View.MeasureSpec.AT_MOST);
                item.measure(desiredWidth, 0); // 计算子项View 的宽高
                height += item.getMeasuredHeight();*/
        }
    }

    return height;
}
 

/**
 * 获取目标控件的位置下标
 * (获取滚动后第一个View的下标)
 *
 * @param layoutManager 布局管理器
 * @param velocityX     X 轴滚动速率
 * @param velocityY     Y 轴滚动速率
 * @return 目标控件的下标
 */
@Override
public int findTargetSnapPosition(RecyclerView.LayoutManager layoutManager,
                                  int velocityX, int velocityY) {
    int target = RecyclerView.NO_POSITION;
    Loge("findTargetSnapPosition, velocityX = " + velocityX + ", velocityY" + velocityY);
    if (null != layoutManager && layoutManager instanceof PagerGridLayoutManager) {
        PagerGridLayoutManager manager = (PagerGridLayoutManager) layoutManager;
        if (manager.canScrollHorizontally()) {
            if (velocityX > PagerConfig.getFlingThreshold()) {
                target = manager.findNextPageFirstPos();
            } else if (velocityX < -PagerConfig.getFlingThreshold()) {
                target = manager.findPrePageFirstPos();
            }
        } else if (manager.canScrollVertically()) {
            if (velocityY > PagerConfig.getFlingThreshold()) {
                target = manager.findNextPageFirstPos();
            } else if (velocityY < -PagerConfig.getFlingThreshold()) {
                target = manager.findPrePageFirstPos();
            }
        }
    }
    Loge("findTargetSnapPosition, target = " + target);
    return target;
}
 

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;
}
 

/**
 * A {@link StaggeredGridLayoutManager} with the given spanCount and orientation.
 */
public static LayoutManagerFactory staggeredGrid(final int spanCount, @Orientation final int orientation) {
    return new LayoutManagerFactory() {
        @Override
        public RecyclerView.LayoutManager create(RecyclerView recyclerView) {
            return new StaggeredGridLayoutManager(spanCount, orientation);
        }
    };
}
 

private void initRecyclerView() {
    adapter = new StagesAdapter(getActivity(), totalPage, listener);
    recyclerView = binding.stageView;
    RecyclerView.LayoutManager layoutManager = new GridLayoutManager(getContext(), 2);
    recyclerView.setLayoutManager(layoutManager);
    recyclerView.setAdapter(adapter);
}
 

@Override
public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
    int dragFlags;
    RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
    if (layoutManager instanceof GridLayoutManager || layoutManager instanceof StaggeredGridLayoutManager) {
        dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN | ItemTouchHelper.START | ItemTouchHelper.END;
    } else {
        dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
    }
    int swipeFlags = 0;
    return makeMovementFlags(dragFlags, swipeFlags);
}
 

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    fab_add=(FloatingActionButton)v.findViewById(R.id.fab);
    fab_add.setOnClickListener(this);
    pg=(ProgressBar)v.findViewById(R.id.progressBar);
    my_routes_recycler = (RecyclerView) v.findViewById(R.id.routeRecycler);
    recycler_adapter = new MyRoutesRecyclerAdapter(my_routes_list,"My",this);
    RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getActivity().getApplicationContext());
    my_routes_recycler.setLayoutManager(mLayoutManager);
    my_routes_recycler.setItemAnimator(new DefaultItemAnimator());
    my_routes_recycler.setAdapter(recycler_adapter);
    routes_async_load=new LoadPersonRoutesAsyncTask(this);
    routes_async_load.execute(getActivity().getSharedPreferences("user_credentials", 0).getString("Id", null));
}
 

/**
 * 最后的位置.
 */
public int findLastVisibleItemPosition() {
    RecyclerView.LayoutManager layoutManager = getLayoutManager();
    if (layoutManager != null) {
        if (layoutManager instanceof LinearLayoutManager) {
            return ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();
        }
        if (layoutManager instanceof GridLayoutManager) {
            return ((GridLayoutManager) layoutManager).findLastVisibleItemPosition();
        }
    }
    return RecyclerView.NO_POSITION;
}
 

@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 = 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:
            lastVisibleItemPosition = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();
            break;
        case GridLayout:
            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);
            break;
    }
}
 

private int getSpanCount(RecyclerView parent) {
    RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
    if (layoutManager instanceof GridLayoutManager) {
        return ((GridLayoutManager) layoutManager).getSpanCount();
    } else {
        return -1;
    }
}
 

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    ButterKnife.bind(this, view);

    RecyclerView.LayoutManager manager = new LinearLayoutManager(getActivity());
    _recycler.setLayoutManager(manager);

    _recycler.setAdapter(getAdapter());
}
 

private static void setupLayoutManagerInternal(RecyclerView recyclerView, final ColumnInfo columnInfo) {
    RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
    if (layoutManager instanceof GridLayoutManager) {
        ((GridLayoutManager) layoutManager).setSpanCount(columnInfo.count);
    }
}
 

@Override
protected RecyclerView.LayoutManager onCreateLayoutManager() {
    return null;
}
 

@Override
public View findSnapView(RecyclerView.LayoutManager layoutManager) {
    VegaLayoutManager custLayoutManager = (VegaLayoutManager) layoutManager;
    return custLayoutManager.findSnapView();
}
 

private void initRecycler_list(AppCompatActivity appCompatActivity){

        recycler_list.setHasFixedSize(true);


        RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(appCompatActivity);
        recycler_list.setLayoutManager(mLayoutManager);
        recycler_list.setItemAnimator(new DefaultItemAnimator());

        mySearchAdapter = new MySearchAdapter(appCompatActivity, R.layout.fragment_dev_week_item);
        recycler_list.setAdapter(mySearchAdapter);
    }
 

private void initRecycler_list(final Context context) {

        RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(context);
        recycler_list.setLayoutManager(mLayoutManager);
        recycler_list.setItemAnimator(new DefaultItemAnimator());

        collectAdapter = new CollectAdapter(context);

        recycler_list.setAdapter(collectAdapter);
    }
 

/**
 * Override to provide a particular adapter target position for snapping.
 *
 * @param layoutManager the {@link RecyclerView.LayoutManager} associated with the attached
 *                      {@link RecyclerView}
 * @param velocityX     fling velocity on the horizontal axis
 * @param velocityY     fling velocity on the vertical axis
 * @return the target adapter position to you want to snap or {@link RecyclerView#NO_POSITION}
 * if no snapping should happen
 */
public abstract int findTargetSnapPosition(RecyclerView.LayoutManager layoutManager, int velocityX,
                                           int velocityY);
 

protected abstract RecyclerView.LayoutManager getLayoutManager();