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

public static void onAttachedToRecyclerView(RecyclerView.Adapter innerAdapter, RecyclerView
        recyclerView, final SpanSizeCallback callback) {
    innerAdapter.onAttachedToRecyclerView(recyclerView);

    RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
    if (layoutManager instanceof GridLayoutManager) {
        final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
        final GridLayoutManager.SpanSizeLookup spanSizeLookup = gridLayoutManager
                .getSpanSizeLookup();

        gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                return callback.getSpanSize(gridLayoutManager, spanSizeLookup, position);
            }
        });
        gridLayoutManager.setSpanCount(gridLayoutManager.getSpanCount());
    }
}
 

/**
 * 解决GrildLayoutManager问题
 *
 * @param recyclerView
 */
@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
	super.onAttachedToRecyclerView(recyclerView);
	RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
	if (layoutManager instanceof GridLayoutManager) {
		final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
		final GridLayoutManager.SpanSizeLookup spanSizeLookup = gridLayoutManager.getSpanSizeLookup();

		gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
			@Override
			public int getSpanSize(int position) {
				if (isHeaderPos(position)) {
					return gridLayoutManager.getSpanCount();
				} else if (isFooterPos(position)) {
					return gridLayoutManager.getSpanCount();
				}
				if (spanSizeLookup != null) {
					return spanSizeLookup.getSpanSize(position);
				}
				return 1;
			}
		});
		gridLayoutManager.setSpanCount(gridLayoutManager.getSpanCount());
	}
}
 

@Override
public void setLayoutManager(LayoutManager layoutManager) {
    if (layoutManager instanceof GridLayoutManager) {
        final GridLayoutManager gridLayoutManager = (GridLayoutManager)layoutManager;
        final GridLayoutManager.SpanSizeLookup spanSizeLookupHolder = gridLayoutManager.getSpanSizeLookup();

        gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                if (mAdapterWrapper.isHeader(position) || mAdapterWrapper.isFooter(position)) {
                    return gridLayoutManager.getSpanCount();
                }
                if (spanSizeLookupHolder != null) {
                    return spanSizeLookupHolder.getSpanSize(position - getHeaderCount());
                }
                return 1;
            }
        });
    }
    super.setLayoutManager(layoutManager);
}
 

/**
 * 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;
}
 

/**
 * 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;
}
 

public static void onAttachedToRecyclerView(RecyclerView.Adapter innerAdapter, RecyclerView recyclerView, final SpanSizeCallback callback) {
    innerAdapter.onAttachedToRecyclerView(recyclerView);

    RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
    if (layoutManager instanceof GridLayoutManager) {
        final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
        final GridLayoutManager.SpanSizeLookup spanSizeLookup = gridLayoutManager.getSpanSizeLookup();

        gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                return callback.getSpanSize(gridLayoutManager, spanSizeLookup, position);
            }
        });
        gridLayoutManager.setSpanCount(gridLayoutManager.getSpanCount());
    }
}
 

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
    if(spanSizeLookup == null){
        GridLayoutManager layoutManager = (GridLayoutManager) parent.getLayoutManager();
        spanSizeLookup = layoutManager.getSpanSizeLookup();
    }
    int spanSize = spanSizeLookup.getSpanSize(parent.getChildLayoutPosition(view));

    if( spanSize == 2){
        if(firstPosition == -1){
            firstPosition = parent.getChildLayoutPosition(view);
        }
        if((parent.getChildLayoutPosition(view) - firstPosition) % 2 == 0){
            outRect.right = space/2;
            outRect.top = space;
        }
        else{
            outRect.left = space/2;
            outRect.top = space;
        }

    }

}
 

/**
 * 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;
}
 

public static void onAttachedToRecyclerView(RecyclerView.Adapter innerAdapter, RecyclerView recyclerView, final SpanSizeCallback callback) {
    innerAdapter.onAttachedToRecyclerView(recyclerView);

    RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
    if (layoutManager instanceof GridLayoutManager) {
        final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
        final GridLayoutManager.SpanSizeLookup spanSizeLookup = gridLayoutManager.getSpanSizeLookup();

        gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                return callback.getSpanSize(gridLayoutManager, spanSizeLookup, position);
            }
        });
        gridLayoutManager.setSpanCount(gridLayoutManager.getSpanCount());
    }
}
 

@Override
public void setLayoutManager(LayoutManager layoutManager) {
    if (layoutManager instanceof GridLayoutManager) {
        final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
        final GridLayoutManager.SpanSizeLookup spanSizeLookupHolder = gridLayoutManager.getSpanSizeLookup();

        gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                if (mAdapterWrapper.isHeaderView(position) || mAdapterWrapper.isFooterView(position)) {
                    return gridLayoutManager.getSpanCount();
                }
                if (spanSizeLookupHolder != null)
                    return spanSizeLookupHolder.getSpanSize(position - getHeaderItemCount());
                return 1;
            }
        });
    }
    super.setLayoutManager(layoutManager);
}
 

private void initLayoutManager(final RecyclerView.LayoutManager layoutManager) {
    this.layoutManager = layoutManager;

    if (layoutManager instanceof GridLayoutManager) {
        final GridLayoutManager castedLayoutManager = (GridLayoutManager) layoutManager;
        final SpanSizeLookup existingLookup = castedLayoutManager.getSpanSizeLookup();

        castedLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                if (isHeader(position) || isFooter(position)) {
                    return castedLayoutManager.getSpanCount();
                }

                return existingLookup.getSpanSize(getRealPosition(position));
            }
        });
    }
}
 

public static void onAttachedToRecyclerView(RecyclerView.Adapter innerAdapter, RecyclerView recyclerView, final SpanSizeCallback callback)
{
    innerAdapter.onAttachedToRecyclerView(recyclerView);

    RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
    if (layoutManager instanceof GridLayoutManager)
    {
        final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
        final GridLayoutManager.SpanSizeLookup spanSizeLookup = gridLayoutManager.getSpanSizeLookup();

        gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup()
        {
            @Override
            public int getSpanSize(int position)
            {
                return callback.getSpanSize(gridLayoutManager, spanSizeLookup, position);
            }
        });
        gridLayoutManager.setSpanCount(gridLayoutManager.getSpanCount());
    }
}
 

/**
 * 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
    public void onAttachedToRecyclerView(RecyclerView recyclerView)
    {
//        Log.d("LoadMoreCommonAdapter","onAttachedToRecyclerView");
        super.onAttachedToRecyclerView(recyclerView);
        final RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager)
        {
            final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
            final GridLayoutManager.SpanSizeLookup spanSizeLookup = gridLayoutManager.getSpanSizeLookup();

            gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup()
            {
                @Override
                public int getSpanSize(int position)
                {
                    if (isShowLoadMore(position))
                    {
                        return gridLayoutManager.getSpanCount();
                    }
                    if (spanSizeLookup != null)
                    {
                        return spanSizeLookup.getSpanSize(position);
                    }
                    return 1;
                }
            });
            gridLayoutManager.setSpanCount(gridLayoutManager.getSpanCount());
        }
    }
 

/**
 * 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;
}
 

/**
 * 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;
}
 

/**
 * 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;
}
 

/**
 * 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;
}