RecyclerView StaggeredGridLayoutManager瀑布流边框刷新问题，错位解决

Posted 2020-12-10 jieth

1.方式--设置统一的ItemDecoration(如果左右边框和中间不对等，可以在xml设置RecyclerView的margin或者padding)

recyclerView.addItemDecoration(new ItemOffsetDecoration(10,5,10,5))

import android.graphics.Rect;
import android.view.View;

import androidx.recyclerview.widget.RecyclerView;
public class ItemOffsetDecoration extends RecyclerView.ItemDecoration {
    private int left;
    private int top;
    private int right;
    private int bottom;

    public ItemOffsetDecoration(int left,int top,int right,int bottom) {
        this.left=left;
        this.top=top;
        this.right=right;
        this.bottom=bottom;
    }
    
    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent,
                               RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        outRect.set(left,top,right,bottom);
    }
}

2.方法,需要针对左右不同去设置 ItemDecoration

import android.graphics.Rect;
import android.view.View;

import androidx.recyclerview.widget.RecyclerView;
import androidx.recyclerview.widget.StaggeredGridLayoutManager;

public class StaggeredDividerItemDecoration extends RecyclerView.ItemDecoration {
    private int top,bottom,left1,left2,right1,right2;
    public StaggeredDividerItemDecoration(int top, int bottom, int left1, int right1, int left2, int right2) {
        this.top = top;
        this.bottom = bottom;
        this.left1 = left1;
        this.left2 = left2;
        this.right1 = right1;
        this.right2 = right2;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        StaggeredGridLayoutManager.LayoutParams params = (StaggeredGridLayoutManager.LayoutParams) view.getLayoutParams();
        // 获取item在span中的下标
        int spanIndex = params.getSpanIndex();
        // 右
        if (spanIndex % 2 == 0) {
            outRect.left = left1;
            outRect.right = right1;
        } else {
            // item为左
            outRect.left = left2;
            outRect.right = right2;
        }
        outRect.top = top;
        outRect.bottom = bottom;
    }
}

但是会出现一个问题，如果图片高度自适应，ItemDecoration会先设置，图片加载后，后边的item左右位置错位，可以通过invalidateItemDecorations()更新ItemDecoration,如果不生效，可以尝试view.post(new Runnable()）的方式。。

recyclerView.invalidateItemDecorations();

view.post(new Runnable() {
                            @Override
                            public void run() {
                                recyclerView.invalidateItemDecorations();
                            }
                        });