Android--如何为RecyclerView添加虚线/点线分隔线？

Question

<shape xmlns:android="http://schemas.android.com/apk/res/android"
       android:shape="line" >

    <stroke
        android:color="@color/blue"
        android:dashGap="12dp"
        android:dashWidth="12dp"
        android:width="1dp" />

</shape>

但是，如果我尝试将此应用为通过调用RecyclerView.AddItemDecoration（new SimpleDividerItemDecoration（getContext（））)访问的可提取资源，则根本不会绘制任何线。

怎么解，这样一条虚线就显示出来了？

Answer 1

只需将您的可绘制资源添加到此项目装饰器中。

DividerItemDecoration decorator = new DividerItemDecoration(ContextCompat.getDrawable(getContext(), R.drawable.line_dashed));
recyclerView.addItemDecoration(decorator);

和DividerItemDecorator类：

public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    private Drawable mDivider;
    private int mPaddingLeft;

    public DividerItemDecoration(Drawable divider) {
        mDivider = divider;
        mPaddingLeft = 0;
    }

    public DividerItemDecoration(Drawable divider, int paddingLeft) {
        mDivider = divider;
        mPaddingLeft = paddingLeft;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        if (mDivider == null) return;
        if (parent.getChildAdapterPosition(view) < 1) return;

        if (getOrientation(parent) == LinearLayoutManager.VERTICAL) {
            outRect.top = mDivider.getIntrinsicHeight();
        } else {
            outRect.left = mDivider.getIntrinsicWidth();
        }
    }

    @Override
    public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
        if (mDivider == null) {
            super.onDrawOver(c, parent, state);
            return;
        }

        if (getOrientation(parent) == LinearLayoutManager.VERTICAL) {
            final int left = parent.getPaddingLeft() + mPaddingLeft;
            final int right = parent.getWidth() - parent.getPaddingRight();
            final int childCount = parent.getChildCount();

            for (int i = 1; i < childCount; i++) {
                final View child = parent.getChildAt(i);
                final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
                final int size = mDivider.getIntrinsicHeight();
                final int top = child.getTop() - params.topMargin;
                final int bottom = top + size;
                mDivider.setBounds(left, top, right, bottom);
                mDivider.draw(c);
            }

        } else { //horizontal
            final int top = parent.getPaddingTop();
            final int bottom = parent.getHeight() - parent.getPaddingBottom();
            final int childCount = parent.getChildCount();

            for (int i = 1; i < childCount; i++) {
                final View child = parent.getChildAt(i);
                final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
                final int size = mDivider.getIntrinsicWidth();
                final int left = child.getLeft() - params.leftMargin;
                final int right = left + size;
                mDivider.setBounds(left, top, right, bottom);
                mDivider.draw(c);
            }
        }
    }

    private int getOrientation(RecyclerView parent) {
        if (parent.getLayoutManager() instanceof LinearLayoutManager) {
            LinearLayoutManager layoutManager = (LinearLayoutManager) parent.getLayoutManager();
            return layoutManager.getOrientation();
        } else
            throw new IllegalStateException("DividerItemDecoration can only be used with a LinearLayoutManager.");
    }
}

应该有用我测试过了。

    android:layerType="software"

<size android:height="1dp"/>