android.support.v7.widget.GridLayoutManager#getSpanCount ( )源码实例Demo

@Override
public GridLayoutManager.SpanSizeLookup getSpanSizeLookup(final GridLayoutManager gridLayoutManager) {
	return new GridLayoutManager.SpanSizeLookup() {
		@Override
		public int getSpanSize(int position) {
			SectionAdapter adapter = getCurrentAdapter();
			if(adapter != null) {
				int viewType = getCurrentAdapter().getItemViewType(position);
				if (viewType == SectionAdapter.VIEW_TYPE_HEADER || viewType == PodcastChannelAdapter.VIEW_TYPE_PODCAST_EPISODE || viewType == PodcastChannelAdapter.VIEW_TYPE_PODCAST_LEGACY) {
					return gridLayoutManager.getSpanCount();
				} else {
					return 1;
				}
			} else {
				return 1;
			}
		}
	};
}
 

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView recyclerView, RecyclerView.State state) {
    final RecyclerView.ViewHolder holder = recyclerView.getChildViewHolder(view);
    final Context context = recyclerView.getContext();

    if(!registered) {
        MaterialViewPagerHelper.registerRecyclerView(context, recyclerView);
        registered = true;
    }

    int headerCells = 1;

    //don't work with stagged
    RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
    if(layoutManager instanceof GridLayoutManager){
        GridLayoutManager gridLayoutManager = (GridLayoutManager)layoutManager;
        headerCells = gridLayoutManager.getSpanCount();
    }

    MaterialViewPagerAnimator animator = MaterialViewPagerHelper.getAnimator(context);
    if (animator != null) {
        if (holder.getAdapterPosition() < headerCells) {
            outRect.top = Math.round(Utils.dpToPx(animator.getHeaderHeight() + 10, context));
        }
    }
}
 

/**
 * In the case mShowLastDivider = false,
 * Returns offset for how many views we don't have to draw a divider for,
 * for LinearLayoutManager it is as simple as not drawing the last child divider,
 * but for a GridLayoutManager it needs to take the span count for the last items into account
 * until we use the span count configured for the grid.
 *
 * @param parent RecyclerView
 * @return offset for how many views we don't have to draw a divider or 1 if its a
 * LinearLayoutManager
 */
private int getLastDividerOffset(RecyclerView parent) {
    if (parent.getLayoutManager() instanceof GridLayoutManager) {
        GridLayoutManager layoutManager = (GridLayoutManager) parent.getLayoutManager();
        GridLayoutManager.SpanSizeLookup spanSizeLookup = layoutManager.getSpanSizeLookup();
        int spanCount = layoutManager.getSpanCount();
        int itemCount = parent.getAdapter().getItemCount();
        for (int i = itemCount - 1; i >= 0; i--) {
            if (spanSizeLookup.getSpanIndex(i, spanCount) == 0) {
                return itemCount - i;
            }
        }
    }

    return 1;
}
 

@Override
public void check(View view, NoMatchingViewException noViewFoundException) {
    if (noViewFoundException != null) {
        throw noViewFoundException;
    }

    RecyclerView recyclerView = (RecyclerView) view;
    if (recyclerView.getLayoutManager() instanceof GridLayoutManager) {
        GridLayoutManager gridLayoutManager = (GridLayoutManager) recyclerView.getLayoutManager();
        int spanCount = gridLayoutManager.getSpanCount();
        if (spanCount != expectedColumnCount) {
            String errorMessage = "expected column count " + expectedColumnCount
                    + " but was " + spanCount;
            throw new AssertionError(errorMessage);
        }
    } else {
        throw new IllegalStateException("no grid layout manager");
    }
}
 

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

    onPageScrollStateChanged(newState);

    if (newState == RecyclerView.SCROLL_STATE_IDLE) {
        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();

        int position = 0;
        if (layoutManager instanceof GridLayoutManager) {
            GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
            position = gridLayoutManager.findFirstVisibleItemPosition();
            int row = gridLayoutManager.getSpanCount();
            position = position / (row * mPageColumn);
        } else if (layoutManager instanceof LinearLayoutManager) {
            LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
            position = linearLayoutManager.findFirstVisibleItemPosition();
        }

        onPageSelected(position);
    }
}
 

/**
 * The number of each page
 *
 * @return
 */
protected int eachPageItemCount() {
    if (mRecyclerView == null) {
        return 0;
    }

    int row = 1;
    RecyclerView.LayoutManager layoutManager = mRecyclerView.getLayoutManager();

    if (layoutManager != null) {
        if (layoutManager instanceof GridLayoutManager) {
            GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
            row = gridLayoutManager.getSpanCount();
        }
    }

    return row * mPageColumn;
}
 

@Override
public void scale(Float currScale, Integer currSpan, MotionEvent ev) {
    Log.d("scale: " + currScale + "/" + currSpan + " :: " +  ev);
    GridLayoutManager lm = (GridLayoutManager)getRecyclerView().getLayoutManager();

    if(lm.getSpanCount() !=currSpan) {
        lm.setSpanCount(currSpan);
        getRecyclerView().getLayoutManager().requestLayout();
    }

    ViewCompat.setScaleX(getRecyclerView(),currScale);
    ViewCompat.setScaleY(getRecyclerView(),currScale);
    getRecyclerView().invalidate();
}
 

private int getSpanCount() {
    if (spanCount != 0) {
        return spanCount;
    }
    GridLayoutManager gridLayoutManager = (GridLayoutManager) recyclerView.getLayoutManager();
    if (gridLayoutManager != null) {
        spanCount = gridLayoutManager.getSpanCount();
        return spanCount;
    }
    return 0;
}
 

private void initLayoutManagerType() {
    this.mLayoutManagerType = mRecyclerViewListener.getCurLayoutManagerType();
    RecyclerView.LayoutManager layoutManager = mRecyclerViewListener.getCurLayoutManager();
    switch (mLayoutManagerType) {
        case FamiliarRecyclerView.LAYOUT_MANAGER_TYPE_LINEAR:
            LinearLayoutManager curLinearLayoutManager = (LinearLayoutManager)layoutManager;
            if (curLinearLayoutManager.getOrientation() == LinearLayoutManager.HORIZONTAL) {
                mOrientation = OrientationHelper.HORIZONTAL;
            } else {
                mOrientation = OrientationHelper.VERTICAL;
            }
            break;
        case FamiliarRecyclerView.LAYOUT_MANAGER_TYPE_GRID:
            GridLayoutManager curGridLayoutManager = (GridLayoutManager)layoutManager;
            mGridSpanCount = curGridLayoutManager.getSpanCount();
            if (curGridLayoutManager.getOrientation() == LinearLayoutManager.HORIZONTAL) {
                mOrientation = OrientationHelper.HORIZONTAL;
            } else {
                mOrientation = OrientationHelper.VERTICAL;
            }
            break;
        case FamiliarRecyclerView.LAYOUT_MANAGER_TYPE_STAGGERED_GRID:
            StaggeredGridLayoutManager curStaggeredGridLayoutManager = (StaggeredGridLayoutManager)layoutManager;
            mGridSpanCount = curStaggeredGridLayoutManager.getSpanCount();
            if (curStaggeredGridLayoutManager.getOrientation() == LinearLayoutManager.HORIZONTAL) {
                mOrientation = OrientationHelper.HORIZONTAL;
            } else {
                mOrientation = OrientationHelper.VERTICAL;
            }
            break;
        default:
            this.mLayoutManagerType = FamiliarRecyclerView.LAYOUT_MANAGER_TYPE_LINEAR;
    }

    initDivisible();
}
 

/**
 * 网格布局需要调用
 *
 * @param recyclerView      recyclerView
 * @param gridLayoutManager gridLayoutManager
 */
public void resetSpan(RecyclerView recyclerView, GridLayoutManager gridLayoutManager) {
    if (recyclerView == null) {
        throw new NullPointerException("recyclerView not allow null");
    }
    if (gridLayoutManager == null) {
        throw new NullPointerException("gridLayoutManager not allow null");
    }
    final int spanCount = gridLayoutManager.getSpanCount();
    //相当于weight
    GridLayoutManager.SpanSizeLookup lookup = new GridLayoutManager.SpanSizeLookup() {
        @Override
        public int getSpanSize(int position) {
            int span;
            int realPosition = getRealPosition(position);
            if (realPosition < 0) {
                //小于header数量
                span = spanCount;
            } else {
                String curGroupId = getGroupName(realPosition);
                String nextGroupId;
                try {
                    //防止外面没判断，导致越界
                    nextGroupId = getGroupName(realPosition + 1);
                } catch (Exception e) {
                    nextGroupId = curGroupId;
                }
                if (!TextUtils.equals(curGroupId, nextGroupId)) {
                    //为本行的最后一个
                    int posFirstInGroup = getFirstInGroupWithCash(realPosition);
                    span = spanCount - (realPosition - posFirstInGroup) % spanCount;
                } else {
                    span = 1;
                }
            }
            return span;
        }
    };
    gridLayoutManager.setSpanSizeLookup(lookup);
}
 

/**
 * Returns a group index for GridLayoutManager.
 * for LinearLayoutManager, always returns position.
 *
 * @param position current view position to draw divider
 * @param parent   RecyclerView
 * @return group index of items
 */
private int getGroupIndex(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.getSpanGroupIndex(position, spanCount);
    }

    return position;
}
 

@Override
protected boolean matchesSafely(View item) {
    if (item instanceof RecyclerView) {
        RecyclerView recyclerView = (RecyclerView) item;
        if (recyclerView.getLayoutManager() != null && recyclerView.getLayoutManager() instanceof GridLayoutManager) {
            GridLayoutManager gridLayoutManager = (GridLayoutManager) recyclerView.getLayoutManager();
            if (gridLayoutManager.getSpanCount() == columnCount) {
                return true;
            }
        }
    }
    return false;
}
 

/**
 * 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;
}
 

/**
 * 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;
}
 

/**
 * Returns a group index for GridLayoutManager.
 * for LinearLayoutManager, always returns position.
 *
 * @param position current view position to draw divider
 * @param parent   RecyclerView
 * @return group index of items
 */
private int getGroupIndex(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.getSpanGroupIndex(position, spanCount);
    }

    return position;
}
 

private int initSpanSize(int position, GridLayoutManager manager) {
    int itemViewType = getItemViewType(position);
    switch (itemViewType) {
        case AdapterLoader.TYPE_BOTTOM:
        case AdapterLoader.TYPE_EMPTY:
        case AdapterLoader.TYPE_ERROR:
            return manager.getSpanCount();
        default:
            return getSpanSize(position);
    }
}
 

public EndlessRecyclerViewScrollListener(GridLayoutManager layoutManager) {
    this.mLayoutManager = layoutManager;
    visibleThreshold = visibleThreshold * layoutManager.getSpanCount();
}
 

private void processScrollListener() {
    if (!(mLayoutManager instanceof LinearLayoutManager)) return;

    LinearLayoutManager linearLayoutManager = (LinearLayoutManager) mLayoutManager;

    int firstItemPosition;
    firstItemPosition = linearLayoutManager.findFirstVisibleItemPosition();
    if (firstItemPosition == RecyclerView.NO_POSITION) return;

    mIndexBar.setSelection(firstItemPosition);

    if (!mSticyEnable) return;
    ArrayList<EntityWrapper> list = mRealAdapter.getItems();
    if (mStickyViewHolder != null && list.size() > firstItemPosition) {
        EntityWrapper wrapper = list.get(firstItemPosition);
        String wrapperTitle = wrapper.getIndexTitle();

        if (EntityWrapper.TYPE_TITLE == wrapper.getItemType()) {
            if (mLastInvisibleRecyclerViewItemView != null && mLastInvisibleRecyclerViewItemView.getVisibility() == INVISIBLE) {
                mLastInvisibleRecyclerViewItemView.setVisibility(VISIBLE);
                mLastInvisibleRecyclerViewItemView = null;
            }

            mLastInvisibleRecyclerViewItemView = linearLayoutManager.findViewByPosition(firstItemPosition);

            if (mLastInvisibleRecyclerViewItemView != null) {
                mLastInvisibleRecyclerViewItemView.setVisibility(INVISIBLE);
            }
        }

        // hide -> show
        if (wrapperTitle == null && mStickyViewHolder.itemView.getVisibility() == VISIBLE) {
            mStickyTitle = null;
            mStickyViewHolder.itemView.setVisibility(INVISIBLE);
        } else {
            stickyNewViewHolder(wrapperTitle);
        }

        // GirdLayoutManager
        if (mLayoutManager instanceof GridLayoutManager) {
            GridLayoutManager gridLayoutManager = (GridLayoutManager) mLayoutManager;
            if (firstItemPosition + gridLayoutManager.getSpanCount() < list.size()) {
                for (int i = firstItemPosition + 1; i <= firstItemPosition + gridLayoutManager.getSpanCount(); i++) {
                    processScroll(linearLayoutManager, list, i, wrapperTitle);
                }
            }
        } else {   // LinearLayoutManager
            if (firstItemPosition + 1 < list.size()) {
                processScroll(linearLayoutManager, list, firstItemPosition + 1, wrapperTitle);
            }
        }
    }
}
 

public SpanSizeLookupWrapper(GridLayoutManager layoutManager,
                             RecyclerFooterAdapterWrapper adapter) {
    this.wrapper = layoutManager.getSpanSizeLookup();
    this.spanSize = layoutManager.getSpanCount();
    this.adapter = adapter;
}
 

public EndlessRecyclerScrollListener(GridLayoutManager layoutManager) {
    mLayoutManager = layoutManager;
    mVisibleThreshold = mVisibleThreshold * layoutManager.getSpanCount();
}