RecyclerView之ItemDecoration在屏幕中增加下划线的一个小demo

来源：互联网发布：淘宝大促时间表2016 编辑：程序博客网时间：2024/05/16 17:29

首先，在activity中：

localVideoRecycView.addItemDecoration(new GridItemDecorator(this));localVideoRecycView.setLayoutManager(new GridLayoutManager(this, 3));

调用ItemDecoration方法

class GridItemDecorator extends RecyclerView.ItemDecoration {    private final Drawable mDivider;    public GridItemDecorator(Context context) {        mDivider = context.getResources().getDrawable(R.drawable.dividing_line);    }    @Override    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {        super.onDraw(c, parent, state);        drawVertical(c, parent);        drawHorizontal(c, parent);    }    // 绘制垂直方向分割线    private void drawVertical(Canvas c, RecyclerView parent) {        int childCount = parent.getChildCount();        for (int i = 0; i < childCount; i++) {            View child = parent.getChildAt(i);            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();            int left = child.getRight() + params.rightMargin;            int top = child.getTop() - params.topMargin;            int right = left + mDivider.getIntrinsicWidth();            int bottom = child.getBottom() + params.bottomMargin;            mDivider.setBounds(left, top, right, bottom);            mDivider.draw(c);        }    }    // 绘制水平方向分割线    private void drawHorizontal(Canvas c, RecyclerView parent) {        int childCount = parent.getChildCount();        for (int i = 0; i < childCount; i++) {            View child = parent.getChildAt(i);            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();            int left = child.getLeft() - params.leftMargin;            int top = child.getBottom() + params.bottomMargin;            int right = child.getRight() + params.rightMargin;            int bottom = top + mDivider.getMinimumHeight();            mDivider.setBounds(left, top, right, bottom);            mDivider.draw(c);        }    }    @Override    public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {        super.getItemOffsets(outRect, itemPosition, parent);        int right = mDivider.getIntrinsicWidth();        int bottom = mDivider.getIntrinsicHeight();        if (isLastSpan(itemPosition, parent)) {            right = 0;        }        if (isLastRow(itemPosition, parent)) {            bottom = 0;        }        outRect.set(0, 0, right, bottom);    }    // 判断是否是最后一行    public boolean isLastRow(int itemPosition, RecyclerView parent) {        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();        if (layoutManager instanceof GridLayoutManager) {            int spanCount = ((GridLayoutManager) layoutManager).getSpanCount();            int itemCount = parent.getAdapter().getItemCount();            if ((itemCount - itemPosition - 1) < spanCount) {                return true;            }        }        return false;    }    // 判断是否是最后一列    public boolean isLastSpan(int itemPosition, RecyclerView parent) {        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();        if (layoutManager instanceof GridLayoutManager) {            int spanCount = ((GridLayoutManager) layoutManager).getSpanCount();            if ((itemPosition + 1) % spanCount == 0) {                return true;            }        }        return false;    }}

然后重写GridItemDecorator方法，在这里，我重写的GridItemDecorator实现的是将屏幕划分为三等份，靠近屏幕端的上下左右没有分割线

如图

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