/**
 * author: Y_Qing
 * date: 2018/5/7
 */

public class SpaceItemDecoration extends RecyclerView.ItemDecoration {
  private int space;
  Paint mPaint;

  public SpaceItemDecoration(int space) {
    this.space = space;
    mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    mPaint.setColor(0xffededed);
    mPaint.setStyle(Paint.Style.FILL);
  }

  private static final int HORIZONTAL = 355;

  @Override
  public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
    int itemViewType = parent.getLayoutManager().getItemViewType(view);
    if (itemViewType == HORIZONTAL) { //根據(jù)ViewType類型來判斷是否展示線
      outRect.bottom = space;
      if (parent.getChildLayoutPosition(view) % 2 == 0) {
        outRect.right = space / 2;
        outRect.left = space;
      } else {
        outRect.right = space;
        outRect.left = space / 2;
      }
    }
  }

  @Override
  public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
    c.save();
    if (parent.getLayoutManager() instanceof GridLayoutManager) {
      if ((((GridLayoutManager) parent.getLayoutManager())).getSpanCount() == 2) {
        draw(c, parent);
      }
    }
    c.restore();

  }

  //繪制橫向 item 分割線
  private void draw(Canvas canvas, RecyclerView parent) {
    int childSize = parent.getChildCount();
    for (int i = 0; i < childSize; i++) {
      View child = parent.getChildAt(i);
      RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) child.getLayoutParams();
      int left = child.getLeft();
      int right = child.getRight();
      int top = child.getBottom() + layoutParams.bottomMargin;
      int bottom = top + space;
      if (mPaint != null) {
        canvas.drawRect(left, top, right, bottom, mPaint);//繪制圖片下放的水平線
      }
      if (parent.getChildLayoutPosition(child) % 2 == 0) {
        canvas.drawRect(0, child.getTop(), left, child.getBottom() + space, mPaint);//繪制左邊圖片的左間線
      }
      top = child.getTop();
      bottom = child.getBottom() + space;
      left = child.getRight() + layoutParams.rightMargin;
      right = left + space;
      if (mPaint != null) {
        canvas.drawRect(left, top, right, bottom, mPaint);//繪制圖片的右間線
      }
    }
  }

}

private void initSpaceLine() {
    if (decor == null) {
      decor = new SpaceItemDecoration(ViewUtil.dp2px(5));
      recycleListView.addItemDecoration(decor);
    }
  }