[英]RecyclerView Decoration doesn't scroll correctly
我有一個RecyclerView,它使用一個簡單的行分隔符裝飾。
裝飾很好,除非將新商品添加到回收站的底部並滾動到視圖中,該裝飾最初是在其最終位置繪制的,然后下面的視圖滾動到位,但裝飾不會滾動。
所需的行為是將裝飾繪制在其開始位置,然后與新項目一起滾動到適當位置。
以下是裝飾的相關部分:
class NormalDecoration extends RecyclerView.ItemDecoration {
private int spacing;
private Drawable drawable;
NormalDecoration(Context context) {
spacing = context.getResources().getDimensionPixelOffset(R.dimen.chat_separator_height);
drawable = ContextCompat.getDrawable(context, R.drawable.chat_divider);
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
if (applySpacing(view, parent)) {
outRect.top += spacing;
}
}
boolean applySpacing(View view, RecyclerView parent) {
int position = parent.getChildAdapterPosition(view);
return position != -1 && position < mItems.size();
}
@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
int dividerLeft = parent.getPaddingLeft();
int dividerRight = parent.getWidth() - parent.getPaddingRight();
for(int index = parent.getChildCount() - 1 ; index >= 0 ; --index) {
View view = parent.getChildAt(index);
if(applySpacing(view, parent)) {
RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) view.getLayoutParams();
int dividerTop = view.getBottom() + params.bottomMargin;
int dividerBottom = dividerTop + spacing;
drawable.setBounds(dividerLeft, dividerTop, dividerRight, dividerBottom);
drawable.draw(c);
}
}
}
}
我的適配器包含以下幫助器:
class Adapter {
public void add(final int index, final IChatMessageItem item) {
mItems.add(index, item);
notifyItemInserted(index);
}
}
這是我將商品添加到回收站的方式,從而導致無法接受的滾動行為:
...
adapter.add(index, item);
layout.scrollToPosition(index);
...
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