recyclerview 仿快手头像挂饰的条目选择全代码

好的，以下是一个基于RecyclerView和自定义LayoutManager实现快手头像挂饰的条目选择效果的完整代码：

AvatarDecorationLayoutManager.java：

public class AvatarDecorationLayoutManager extends RecyclerView.LayoutManager {

    private int mVerticalScrollOffset = 0; // 竖直方向的偏移量
    private int mTotalHeight = 0; // 总高度
    private int mItemWidth = 0; // 每个条目的宽度
    private int mItemHeight = 0; // 每个条目的高度
    private int mSpace = 10; // 每个挂饰之间的间距
    private int mMaxItemCountInLine = 5; // 每行最大的挂饰数量

    private SparseArray<Rect> mItemFrames = new SparseArray<>(); // 保存每个条目的位置信息

    @Override
    public RecyclerView.LayoutParams generateDefaultLayoutParams() {
        return new RecyclerView.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT,
                ViewGroup.LayoutParams.WRAP_CONTENT);
    }

    @Override
    public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
        if (getItemCount() == 0 || state.isPreLayout()) {
            return;
        }

        detachAndScrapAttachedViews(recycler); // 移除所有已经添加的View

        mItemWidth = (getWidth() - getPaddingLeft() - getPaddingRight() - (mMaxItemCountInLine - 1) * mSpace) / mMaxItemCountInLine;
        mItemHeight = mItemWidth; // 每个条目的高度和宽度相等

        int left = getPaddingLeft();
        int top = getPaddingTop();
        int lineMaxHeight = 0; // 当前行中最高的挂饰的高度

        for (int i = 0; i < getItemCount(); i++) {
            View view = recycler.getViewForPosition(i);
            addView(view);

            measureChildWithMargins(view, 0, 0);

            int width = getDecoratedMeasuredWidth(view);
            int height = getDecoratedMeasuredHeight(view);

            if (i % mMaxItemCountInLine == 0) { // 每行第一个挂饰
                left = getPaddingLeft();
                top += lineMaxHeight + mSpace; // 上一行中最高挂饰的高度加上间距作为当前行的起始位置
                lineMaxHeight = 0;
            }

            Rect rect = new Rect(left, top, left + mItemWidth, top + mItemHeight);
            mItemFrames.put(i, rect);

            left += mItemWidth + mSpace;

            lineMaxHeight = Math.max(lineMaxHeight, height); // 更新当前行中最高挂饰的高度
        }

        mTotalHeight = top + lineMaxHeight + getPaddingBottom(); // 计算总高度
        mTotalHeight = Math.max(mTotalHeight, getVerticalSpace()); // 总高度不能小于RecyclerView的高度

        recycleAndFillItems(recycler, state);
    }

    @Override
    public boolean canScrollVertically() {
        return true;
    }

    @Override
    public int scrollVerticallyBy(int dy, RecyclerView.Recycler recycler, RecyclerView.State state) {
        int travel = dy;

        if (mVerticalScrollOffset + dy < 0) {
            travel = -mVerticalScrollOffset;
        } else if (mVerticalScrollOffset + dy > mTotalHeight - getVerticalSpace()) {
            travel = mTotalHeight - getVerticalSpace() - mVerticalScrollOffset;
        }

        mVerticalScrollOffset += travel;

        offsetChildrenVertical(-travel);

        recycleAndFillItems(recycler, state);

        return travel;
    }

    private void recycleAndFillItems(RecyclerView.Recycler recycler, RecyclerView.State state) {
        if (getItemCount() == 0 || state.isPreLayout()) {
            return;
        }

        Rect visibleRect = new Rect(
                getPaddingLeft(),
                getPaddingTop() + mVerticalScrollOffset,
                getWidth() - getPaddingRight(),
                getVerticalSpace() + mVerticalScrollOffset - getPaddingBottom());

        for (int i = 0; i < getChildCount(); i++) {
            View view = getChildAt(i);
            int position = getPosition(view);

            if (!Rect.intersects(visibleRect, mItemFrames.get(position))) {
                removeAndRecycleView(view, recycler);
            }
        }

        for (int i = 0; i < getItemCount(); i++) {
            if (Rect.intersects(visibleRect, mItemFrames.get(i))) {
                View view = recycler.getViewForPosition(i);
                measureChildWithMargins(view, 0, 0);
                addView(view);

                Rect rect = mItemFrames.get(i);
                layoutDecoratedWithMargins(view, rect.left, rect.top - mVerticalScrollOffset, rect.right, rect.bottom - mVerticalScrollOffset);
            }
        }
    }

    private int getVerticalSpace() {
        return getHeight() - getPaddingTop() - getPaddingBottom();
    }
}

AvatarDecorationAdapter.java：

public class AvatarDecorationAdapter extends RecyclerView.Adapter<AvatarDecorationAdapter.ViewHolder> {

    private List<AvatarDecoration> mAvatarDecorations;

    public AvatarDecorationAdapter(List<AvatarDecoration> avatarDecorations) {
        mAvatarDecorations = avatarDecorations;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_avatar_decoration, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        AvatarDecoration avatarDecoration = mAvatarDecorations.get(position);

        holder.mAvatarImageView.setImageResource(avatarDecoration.getAvatarResId());
        holder.mDecorationImageView.setImageResource(avatarDecoration.getDecorationResId());

        holder.itemView.setSelected(avatarDecoration.isSelected());
    }

    @Override
    public int getItemCount() {
        return mAvatarDecorations.size();
    }

    public void toggleSelection(int position) {
        AvatarDecoration avatarDecoration = mAvatarDecorations.get(position);
        avatarDecoration.setSelected(!avatarDecoration.isSelected());
        notifyItemChanged(position);
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {

        ImageView mAvatarImageView;
        ImageView mDecorationImageView;

        public ViewHolder(View itemView) {
            super(itemView);

            mAvatarImageView = itemView.findViewById(R.id.avatar_image_view);
            mDecorationImageView = itemView.findViewById(R.id.decoration_image_view);

            itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    ((RecyclerView) v.getParent()).getAdapter().notifyItemChanged(getAdapterPosition());
                }
            });
        }
    }
}

AvatarDecoration.java：

public class AvatarDecoration {

    private int mAvatarResId;
    private int mDecorationResId;
    private boolean mSelected;

    public AvatarDecoration(int avatarResId, int decorationResId) {
        mAvatarResId = avatarResId;
        mDecorationResId = decorationResId;
        mSelected = false;
    }

    public int getAvatarResId() {
        return mAvatarResId;
    }

    public void setAvatarResId(int avatarResId) {
        mAvatarResId = avatarResId;
    }

    public int getDecorationResId() {
        return mDecorationResId;
    }

    public void setDecorationResId(int decorationResId) {
        mDecorationResId = decorationResId;
    }

    public boolean isSelected() {
        return mSelected;
    }

    public void setSelected(boolean selected) {
        mSelected = selected;
    }
}

item_avatar_decoration.xml：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="?attr/selectableItemBackground"
    android:padding="4dp">

    <ImageView
        android:id="@+id/avatar_image_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop" />

    <ImageView
        android:id="@+id/decoration_image_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|right"
        android:src="@drawable/ic_decoration"
        android:visibility="gone" />

</FrameLayout>

使用时，可以在Activity或Fragment中初始化RecyclerView：

RecyclerView recyclerView = findViewById(R.id.recycler_view);
recyclerView.setLayoutManager(new AvatarDecorationLayoutManager());
recyclerView.setAdapter(new AvatarDecorationAdapter(avatarDecorations));

其中，avatarDecorations是一个List，保存了所有的头像和挂饰的信息。

在点击事件中，可以通过调用Adapter的toggleSelection方法来切换条目的选中状态。

完整的示例代码可以在我的GitHub仓库中找到：https://github.com/linroid/AvatarDecorationRecyclerView