RecyclerView万用分隔线：轻松实现布局样式，自定义分隔线

2023-12-31 01:12:05

自定义 RecyclerView 分隔线：分步指南

简介

拥有整洁有序的布局对于任何应用程序来说都是至关重要的。分隔线可以帮助你实现这一目标，通过创建分隔不同项目或部分的清晰视觉边界。在本指南中，我们将深入了解如何创建自定义 RecyclerView 分隔线，支持各种布局管理器，并自定义其外观以满足你的特定需求。

创建自定义 ItemDecoration

ItemDecoration 是 RecyclerView 用于在子视图周围绘制装饰元素的机制，例如分隔线。要创建自定义分隔线，你需要实现一个扩展 RecyclerView.ItemDecoration 的类。该类将负责绘制分隔线并为每个子视图预留空间。

以下是一个示例 ItemDecoration，可绘制水平和垂直分隔线：

public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    private int horizontalDividerWidth;
    private int verticalDividerWidth;
    private boolean drawEdgeDivider;

    public DividerItemDecoration(int horizontalDividerWidth, int verticalDividerWidth, boolean drawEdgeDivider) {
        this.horizontalDividerWidth = horizontalDividerWidth;
        this.verticalDividerWidth = verticalDividerWidth;
        this.drawEdgeDivider = drawEdgeDivider;
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        super.onDraw(c, parent, state);

        // 绘制水平分隔线
        drawHorizontalDivider(c, parent);

        // 绘制垂直分隔线
        drawVerticalDivider(c, parent);
    }

    private void drawHorizontalDivider(Canvas c, RecyclerView parent) {
        int childCount = parent.getChildCount();

        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);

            // 获取子视图布局参数
            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();

            // 计算分隔线的起点和终点
            int left = child.getLeft() - horizontalDividerWidth / 2;
            int right = child.getRight() + horizontalDividerWidth / 2;
            int top = child.getBottom() + params.bottomMargin;
            int bottom = top + horizontalDividerWidth;

            // 绘制分隔线
            c.drawRect(left, top, right, bottom, dividerPaint);
        }
    }

    private void drawVerticalDivider(Canvas c, RecyclerView parent) {
        int childCount = parent.getChildCount();

        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);

            // 获取子视图布局参数
            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();

            // 计算分隔线的起点和终点
            int left = child.getRight() + params.rightMargin;
            int right = left + verticalDividerWidth;
            int top = child.getTop() - verticalDividerWidth / 2;
            int bottom = child.getBottom() + verticalDividerWidth / 2;

            // 绘制分隔线
            c.drawRect(left, top, right, bottom, dividerPaint);
        }
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);

        // 为每个子视图预留分隔线空间
        outRect.set(0, 0, verticalDividerWidth, horizontalDividerWidth);
    }
}

添加到 RecyclerView

一旦你创建了自定义 ItemDecoration，只需将其添加到 RecyclerView 中即可。

RecyclerView recyclerView = findViewById(R.id.recyclerView);
recyclerView.addItemDecoration(new DividerItemDecoration(10, 10, true));

自定义分隔线外观

你可以通过设置 ItemDecoration 属性来自定义分隔线的外观，如下所示：

// 设置水平分隔线的宽度
dividerItemDecoration.setHorizontalDividerWidth(20);

// 设置垂直分隔线的宽度
dividerItemDecoration.setVerticalDividerWidth(20);

// 设置是否绘制边缘分隔线
dividerItemDecoration.setDrawEdgeDivider(true);

// 设置分隔线颜色
dividerItemDecoration.setDividerColor(Color.RED);