Как я могу реализовать GridDividerItemDecoration для RecyclerView с помощью GridLayoutManager и заголовка раздела, реализованного с помощью SpanSizeLookup?

Question

Я использовал RecyclerView с GridLayoutManager вместе с заголовком раздела для Grid, реализованным с использованием SpanSizeLookup (путем увеличения размера диапазона для позиций заголовков в списке). Теперь, как я могу изменить GridDividerItemDecoration, чтобы он работал в этом случае. Прямо сейчас разделители находятся в случайных местах в GridView.

Мой код:

public class GridDividerItemDecoration extends RecyclerView.ItemDecoration {

private int mchildOffset;


private Drawable mHorizontalDivider;
private Drawable mVerticalDivider;
private int mNumColumns;

/**
 * Sole constructor. Takes in {@link Drawable} objects to be used as
 * horizontal and vertical dividers.
 *
 * @param horizontalDivider A divider {@code Drawable} to be drawn on the
 *                          rows of the grid of the RecyclerView
 * @param verticalDivider   A divider {@code Drawable} to be drawn on the
 *                          columns of the grid of the RecyclerView
 * @param numColumns        The number of columns in the grid of the RecyclerView
 */
public GridDividerItemDecoration(Drawable horizontalDivider, Drawable verticalDivider, int numColumns, int childOffset) {
    mHorizontalDivider = horizontalDivider;
    mVerticalDivider = verticalDivider;
    mNumColumns = numColumns;
    mchildOffset = childOffset;

}

/**
 * Draws horizontal and/or vertical dividers onto the parent RecyclerView.
 *
 * @param canvas The {@link Canvas} onto which dividers will be drawn
 * @param parent The RecyclerView onto which dividers are being added
 * @param state  The current RecyclerView.State of the RecyclerView
 */
@Override
public void onDraw(Canvas canvas, RecyclerView parent, RecyclerView.State state) {
    drawHorizontalDividers(canvas, parent);
    drawVerticalDividers(canvas, parent);

}

/**
 * Determines the size and location of offsets between items in the parent
 * RecyclerView.
 *
 * @param outRect The {@link Rect} of offsets to be added around the child view
 * @param view    The child view to be decorated with an offset
 * @param parent  The RecyclerView onto which dividers are being added
 * @param state   The current RecyclerView.State of the RecyclerView
 */
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
    super.getItemOffsets(outRect, view, parent, state);

    boolean childIsInLeftmostColumn = (parent.getChildAdapterPosition(view) % mNumColumns) == 0;
    if (!childIsInLeftmostColumn) {
        outRect.left = mHorizontalDivider.getIntrinsicWidth();
    }

    boolean childIsInFirstRow = (parent.getChildAdapterPosition(view)) < mNumColumns;
    if (!childIsInFirstRow) {
        outRect.top = mVerticalDivider.getIntrinsicHeight();
    }
}

/**
 * Adds horizontal dividers to a RecyclerView with a GridLayoutManager or its
 * subclass.
 *
 * @param canvas The {@link Canvas} onto which dividers will be drawn
 * @param parent The RecyclerView onto which dividers are being added
 */
private void drawHorizontalDividers(Canvas canvas, RecyclerView parent) {
    int childCount = parent.getChildCount();
    int rowCount = childCount / mNumColumns;
    int lastRowChildCount = childCount % mNumColumns;

    for (int i = 1; i < mNumColumns; i++) {
        int lastRowChildIndex;
        if (i < lastRowChildCount) {
            lastRowChildIndex = i + (rowCount * mNumColumns);
        } else {
            lastRowChildIndex = i + ((rowCount - 1) * mNumColumns);
        }

        View firstRowChild = parent.getChildAt(i);
        View lastRowChild = parent.getChildAt(lastRowChildIndex);

        int dividerTop = firstRowChild.getTop();
        int dividerRight = firstRowChild.getLeft();
        int dividerLeft = dividerRight - mHorizontalDivider.getIntrinsicWidth();
        int dividerBottom = lastRowChild != null ? lastRowChild.getBottom() : -1;


        mHorizontalDivider.setBounds(dividerLeft, dividerTop, dividerRight, dividerBottom);
        mHorizontalDivider.draw(canvas);
    }
}

/**
 * Adds vertical dividers to a RecyclerView with a GridLayoutManager or its
 * subclass.
 *
 * @param canvas The {@link Canvas} onto which dividers will be drawn
 * @param parent The RecyclerView onto which dividers are being added
 */
private void drawVerticalDividers(Canvas canvas, RecyclerView parent) {
    int childCount = parent.getChildCount();
    int rowCount = childCount / mNumColumns;
    int rightmostChildIndex;
    for (int i = 1; i <= rowCount; i++) {
        if (i == rowCount) {
            rightmostChildIndex = parent.getChildCount() - 1;
        } else {
            rightmostChildIndex = (i * mNumColumns) + mNumColumns - 1;
        }

        View leftmostChild = parent.getChildAt(i * mNumColumns);
        View rightmostChild = parent.getChildAt(rightmostChildIndex);

        int dividerLeft = leftmostChild != null ? leftmostChild.getLeft() : -1;
        int dividerBottom = leftmostChild != null ? leftmostChild.getTop() : -1;
        int dividerTop = dividerBottom - mVerticalDivider.getIntrinsicHeight();
        int dividerRight = rightmostChild != null ? rightmostChild.getRight() : -1;

        if (dividerLeft != -1 || dividerRight != -1 || dividerBottom != -1) {
            mVerticalDivider.setBounds(dividerLeft, dividerTop, dividerRight, dividerBottom);
            mVerticalDivider.draw(canvas);
        }
    }
}
}