实现 GridLayoutManger 和 StaggeredGridLayoutManager 混排的工具类

news2024/9/20 18:33:31

序言

最近项目中要实现瀑布流的混排，于是写了一些工具类来实现。使用了这个工具类，可以处理混排，可以处理间距。都集成在一个接口中。

最后效果类似这样。

在这里插入图片描述

工具类

GridItemUI

下面的这个类是用来实现在GridLayouManger中混排的。

package com.trs.baseapp.news.list.ui.staggered;

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

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.trs.library.callback.action.TRSFunction;


/**
 * <pre>
 * Created by zhuguohui
 * Date: 2024/8/23
 * Time: 10:21
 * Desc:用来实现GridItem混排的接口。
 *
 * 用法如下:
 * <code>
 *       int spanCount = 3;
 *         GridLayoutManager gridLayoutManager = new GridLayoutManager(getContext(), spanCount);
 *         GridItemUI.setSpanSizeLookup(gridLayoutManager,position->adapter.getItems().get(position));
 *         GridItemUI.addItemDecoration(recyclerView, spanCount, position -> adapter.getItems().get(position));
 * </code>
 * </pre>
 */
public interface GridItemUI {
    /**
     * 获取item之间的水平间隔 horizontal
     *
     * @return
     */
    int getItemHorizontalSpaceSize();

    /**
     * 获取Item 之间垂直方向的间隔
     *
     * @return
     */
    int getItemVerticalSpaceSize();


    static void setSpanSizeLookup(GridLayoutManager gridLayoutManager, TRSFunction<Integer, Object> findAdapterContentFunction) {
        gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                Object o = findAdapterContentFunction.call(position);
                if (o instanceof GridItemUI) {
                    return 1;
                }
                return gridLayoutManager.getSpanCount();
            }
        });
    }

    static void addItemDecoration(RecyclerView recyclerView, int spanCount, TRSFunction<Integer, Object> findAdapterContentFunction) {
        recyclerView.addItemDecoration(new RecyclerView.ItemDecoration() {
            @Override
            public void getItemOffsets(@NonNull Rect outRect, @NonNull View view, @NonNull RecyclerView parent, @NonNull RecyclerView.State state) {
                int position = parent.getChildAdapterPosition(view);
                Object o = findAdapterContentFunction.call(position);
                if (o instanceof GridItemUI) {
                    Pair<Boolean, Boolean> pair = getIsFirstLineAndIsLineFirstItem(position);
                    GridItemUI itemUI = (GridItemUI) o;
                    int hs = itemUI.getItemHorizontalSpaceSize();
                    int vs = itemUI.getItemVerticalSpaceSize();
                    outRect.left = pair.second ? hs : 0;
                    outRect.right = hs;
                    outRect.top = pair.first ? vs : 0;
                    outRect.bottom = vs;
                } else {
                    super.getItemOffsets(outRect, view, parent, state);
                }
            }

            private Pair<Boolean, Boolean> getIsFirstLineAndIsLineFirstItem(int position) {
                int beforeItemCount = 0;
                int checkPosition = position;
                do {
                    checkPosition--;
                    if (checkPosition < 0) {
                        break;
                    }
                    Object o = findAdapterContentFunction.call(checkPosition);
                    if (!(o instanceof GridItemUI)) {
                        break;
                    }
                    beforeItemCount++;

                } while (true);

                boolean lineFirst = beforeItemCount % spanCount == 0;
                boolean firstLine = beforeItemCount < spanCount;
                return new Pair<>(firstLine, lineFirst);
            }
        });
    }

}

用法


   int spanCount = 3;
          GridLayoutManager gridLayoutManager = new GridLayoutManager(getContext(), spanCount);
          //以下代码实现混排
          GridItemUI. setSpanSizeLookup(gridLayoutManager,position->adapter. getItems().get(position));
          //以下代码实现间距
          GridItemUI. addItemDecoration(recyclerView, spanCount, position -> adapter. getItems().get(position));

StaggeredUI

package com.trs.baseapp.news.list.ui.staggered;

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

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

import com.trs.library.callback.action.TRSFunction;

/**
 * <pre>
 * Created by zhuguohui
 * Date: 2024/8/28
 * Time: 11:24
 * Desc:实现了该接口，表示当前UI是为了瀑布流设计的
 * </pre>
 */
public interface StaggeredUI {

    /**
     * 用来查找adapter中对应position数据的接口
     */
    interface FindAdapterContentFunction{
        Object call(int position);
    }
    static void onViewAttachedToWindow(@NonNull RecyclerView.ViewHolder holder,FindAdapterContentFunction findAdapterContentFunction) {

        int adapterPosition = holder.getAdapterPosition();
        Object o = findAdapterContentFunction.call(adapterPosition);
        StaggeredGridLayoutManager.LayoutParams params = (StaggeredGridLayoutManager.LayoutParams) holder.itemView.getLayoutParams();
        if (o instanceof StaggeredUI) {
            params.setFullSpan(false);
        } else {
            params.setFullSpan(true);
        }


    }

    static void addItemDecoration(RecyclerView recyclerView, int spanCount, FindAdapterContentFunction findAdapterContentFunction) {
        recyclerView.addItemDecoration(new RecyclerView.ItemDecoration() {
            @Override
            public void getItemOffsets(@NonNull Rect outRect, @NonNull View view, @NonNull RecyclerView parent, @NonNull RecyclerView.State state) {
                int position = parent.getChildAdapterPosition(view);
                Object o = findAdapterContentFunction.call(position);

                if (o instanceof StaggeredUI itemUI) {
                    StaggeredGridLayoutManager.LayoutParams lp = (StaggeredGridLayoutManager.LayoutParams) view.getLayoutParams();
                    int hs = itemUI.getItemHorizontalSpaceSize();
                    int vs = itemUI.getItemVerticalSpaceSize();
                    outRect.left = lp.getSpanIndex() == 0 ? hs : 0;
                    outRect.right = hs;
                    outRect.top = isFirstLine(position) ? vs : 0;
                    outRect.bottom = vs;
                } else {
                    super.getItemOffsets(outRect, view, parent, state);
                }
            }

            private boolean isFirstLine(int position) {
                int beforeItemCount = 0;
                int checkPosition = position;
                do {
                    checkPosition--;
                    if (checkPosition < 0) {
                        break;
                    }
                    Object o = findAdapterContentFunction.call(checkPosition);
                    if (!(o instanceof StaggeredUI)) {
                        break;
                    }
                    beforeItemCount++;

                } while (true);


                boolean firstLine = beforeItemCount < spanCount;
                return firstLine;
            }
        });
    }

    /**
     * 返回垂直间距
     * @return
     */
    int getItemVerticalSpaceSize();

    /**
     * 返回水平间距
     * @return
     */
    int getItemHorizontalSpaceSize();
}