RecyclerView LayoutManager 在不同的行上有不同的跨度计数

问题描述

我想要一个 RecyclerView.LayoutManager，它允许我为不同的行指定不同的跨度计数作为重复模式.例如，包含 10 个项目的 2,3 将如下所示:

I want a RecyclerView.LayoutManager that allows me to specify different span counts for different rows as a repeating pattern. For example 2,3 with 10 items would look like this:

  -------------
  |     |     |
  |     |     |
  -------------
  |   |   |   |
  |   |   |   |
  -------------
  |     |     |
  |     |     |
  -------------
  |   |   |   |
  |   |   |   |
  -------------

我可以想出一种使用 GridLayoutManager 和 SpanSizeLookup 来破解这个问题的方法，但有人想出更简洁的方法来做到这一点吗?

I can think of a way to hack this with GridLayoutManager and SpanSizeLookup but has anybody come up with a cleaner way to do this?

推荐答案

要做你想做的事，你可能必须自己编写LayoutManager.

To do what you want, you probably have to write your own LayoutManager.

我认为这更容易:

    // Create a grid layout with 6 columns
    // (least common multiple of 2 and 3)
    GridLayoutManager layoutManager = new GridLayoutManager(this, 6);

    layoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
        @Override
        public int getSpanSize(int position) {
            // 5 is the sum of items in one repeated section
            switch (position % 5) {
            // first two items span 3 columns each
            case 0:
            case 1:
                return 3;
            // next 3 items span 2 columns each
            case 2:
            case 3:
            case 4:
                return 2;
            }
            throw new IllegalStateException("internal error");
        }
    });

如果你的网格项需要知道它的跨度大小，你可以在 ViewHolder 中找到它:

        // this line can return null when the view hasn't been added to the RecyclerView yet
        RecyclerView recyclerView = (RecyclerView) itemView.getParent();
        GridLayoutManager gridLayoutManager = (GridLayoutManager) recyclerView.getLayoutManager();
        int spanSize = gridLayoutManager.getSpanSizeLookup().getSpanSize(getLayoutPosition());

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