ساخت آداپتر واکنشی و ناهمگون در کاتلین – راهنمای کاربردی

1class ItemViewHolder extends RecyclerView.ViewHolder{
2    
3}
4class LoadingViewHolder extends RecyclerView.ViewHolder{
5   
6}
7override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
8    return if (viewType == LOADING) {
9        LoadingViewHolder(mLayoutInflater.inflate(R.layout.loading, parent, false))
10    } else {
11        ItemViewHolder(mLayoutInflater.inflate(R.layout.item_layout, parent, false))
12    }
13}

1abstract class FeedItemViewBinder<M, in VH : ViewHolder>(
2    val modelClass: Class<out M>) : DiffUtil.ItemCallback<M>() {
3
4    abstract fun createViewHolder(parent: ViewGroup): ViewHolder
5    abstract fun bindViewHolder(model: M, viewHolder: VH)
6    abstract fun getFeedItemType(): Int
7
8    // Having these as non abstract because not all the viewBinders are required to implement them.
9    open fun onViewRecycled(viewHolder: VH) = Unit
10    open fun onViewDetachedFromWindow(viewHolder: VH) = Unit
11}

1typealias FeedItemClass = Class<out Any>
2typealias FeedItemBinder = FeedItemViewBinder<Any, ViewHolder>
3
4internal class FeedDiffCallback(
5    private val viewBinders: Map<FeedItemClass, FeedItemBinder>
6) : DiffUtil.ItemCallback<Any>() {
7
8    override fun areItemsTheSame(oldItem: Any, newItem: Any): Boolean {
9        if (oldItem::class != newItem::class) {
10            return false
11        }
12        return viewBinders[oldItem::class.java]?.areItemsTheSame(oldItem, newItem) ?: false
13    }
14
15    override fun areContentsTheSame(oldItem: Any, newItem: Any): Boolean {
16        return viewBinders[oldItem::class.java]?.areContentsTheSame(oldItem, newItem) ?: false
17    }
18}

1class FeedAdapter(
2    private val viewBinders: Map<FeedItemClass, FeedItemBinder>
3) : ListAdapter<Any, ViewHolder>(FeedDiffCallback(viewBinders)) {
4
5    private val viewTypeToBinders = viewBinders.mapKeys { it.value.getFeedItemType() }
6
7    private fun getViewBinder(viewType: Int): FeedItemBinder = viewTypeToBinders.getValue(viewType)
8
9    override fun getItemViewType(position: Int): Int =
10        viewBinders.getValue(super.getItem(position).javaClass).getFeedItemType()
11
12    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
13        return getViewBinder(viewType).createViewHolder(parent)
14    }
15
16    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
17        return getViewBinder(getItemViewType(position)).bindViewHolder(getItem(position), holder)
18    }
19
20    override fun onViewRecycled(holder: ViewHolder) {
21        getViewBinder(holder.itemViewType).onViewRecycled(holder)
22        super.onViewRecycled(holder)
23    }
24
25    override fun onViewDetachedFromWindow(holder: ViewHolder) {
26        getViewBinder(holder.itemViewType).onViewDetachedFromWindow(holder)
27        super.onViewDetachedFromWindow(holder)
28    }
29}

1override fun getItemViewType(position: Int): Int =
2    viewBinders.getValue(super.getItem(position).javaClass).getFeedItemType()

1class VerticalImagesViewBinder(val block : (data: VeriticalImageModel) -> Unit) : FeedItemViewBinder<VeriticalImageModel, VerticalImagesViewHolder>(
2    VeriticalImageModel::class.java) {
3
4    override fun createViewHolder(parent: ViewGroup): VerticalImagesViewHolder {
5        return VerticalImagesViewHolder(
6            LayoutInflater.from(parent.context).inflate(getFeedItemType(), parent, false),block)
7    }
8
9    override fun bindViewHolder(model: VeriticalImageModel, viewHolder: VerticalImagesViewHolder) {
10        viewHolder.bind(model)
11    }
12
13    override fun getFeedItemType() = R.layout.adapter_vertical_image
14
15    override fun areContentsTheSame(oldItem: VeriticalImageModel, newItem: VeriticalImageModel) = oldItem == newItem
16
17    override fun areItemsTheSame(oldItem: VeriticalImageModel, newItem: VeriticalImageModel) : Boolean {
18        return oldItem.Image == newItem.Image
19    }
20}
21
22
23class VerticalImagesViewHolder(val view : View, val block : (data: VeriticalImageModel) -> Unit)
24    : RecyclerView.ViewHolder(view) {
25
26    fun bind(data: VeriticalImageModel) {
27
28        itemView.setOnClickListener {
29            block(data)
30        }
31
32        itemView.apply {
33            Glide
34                .with(itemView.context)
35                .load(data.Image)
36                .centerCrop()
37                .into(im_vertical)
38        }
39    }
40}

1private var adapter: FeedAdapter? = null
2
3fun verticalImageClick(data : VeriticalImageModel){
4        ...
5}
6
7private fun showFeedItems(recyclerView: RecyclerView, list: ArrayList<Any>?) {
8    if (adapter == null) {
9        val viewBinders = mutableMapOf<FeedItemClass, FeedItemBinder>()
10        val verticalImagesViewBinder = VerticalImagesViewBinder { data : VeriticalImageModel ->
11            verticalImageClick(data)}
12        @Suppress("UNCHECKED_CAST")
13        viewBinders.put(
14            verticalImagesViewBinder.modelClass,
15            verticalImagesViewBinder as FeedItemBinder)
16        adapter = FeedAdapter(viewBinders)
17    }
18    recyclerView.apply {
19        layoutManager = LinearLayoutManager(this@MainActivity, LinearLayoutManager.VERTICAL,false)
20    }
21    if (recyclerView.adapter == null) {
22        recyclerView.adapter = adapter
23    }
24    (recyclerView.adapter as FeedAdapter).submitList(list ?: emptyList())
25}

1class HorizontalImagesListViewBinder(val block : (data: HorizontalImageModel) -> Unit)
2    : FeedItemViewBinder<HorizontalImageListModel, HorizontalImagesListViewHolder>(
3    HorizontalImageListModel::class.java) {
4
5    override fun createViewHolder(parent: ViewGroup): HorizontalImagesListViewHolder {
6        return HorizontalImagesListViewHolder(
7            LayoutInflater.from(parent.context).inflate(getFeedItemType(), parent, false),block)
8    }
9
10    override fun bindViewHolder(model: HorizontalImageListModel, viewHolder: HorizontalImagesListViewHolder) {
11        viewHolder.bind(model)
12    }
13
14    override fun getFeedItemType() = R.layout.adapter_recycleriew
15
16    override fun areContentsTheSame(oldItem: HorizontalImageListModel, newItem: HorizontalImageListModel) = oldItem == newItem
17
18    override fun areItemsTheSame(oldItem: HorizontalImageListModel, newItem: HorizontalImageListModel) : Boolean {
19        return oldItem.id == newItem.id
20    }
21}
22
23
24class HorizontalImagesListViewHolder(val view : View, val block : (data: HorizontalImageModel) -> Unit)
25    : RecyclerView.ViewHolder(view) {
26
27    fun bind(data: HorizontalImageListModel) {
28
29        var adapter : FeedAdapter? = null
30
31        itemView.apply {
32            val horizontalImagesViewBinder = HorizontalImagesViewBinder { horizontalImageModel : HorizontalImageModel ->
33                block(horizontalImageModel)}
34            val viewBinders = mutableMapOf<FeedItemClass, FeedItemBinder>()
35            @Suppress("UNCHECKED_CAST")
36            viewBinders.put(
37                horizontalImagesViewBinder.modelClass,
38                horizontalImagesViewBinder as FeedItemBinder)
39            adapter = FeedAdapter(viewBinders)
40            tv_horizontal_header?.text = data.title
41            adapter_recycllerview?.apply {
42
43                layoutManager = LinearLayoutManager(adapter_recycllerview?.context,
44                    LinearLayoutManager.HORIZONTAL,false)
45                if (adapter_recycllerview?.adapter == null) {
46                    adapter_recycllerview?.adapter = adapter
47                }
48                (adapter_recycllerview?.adapter as FeedAdapter).submitList(
49                    data.Images as List<Any>? ?: emptyList())
50            }
51        }
52    }
53}

1private lateinit var horizontalImagesViewBinder : HorizontalImagesListViewBinder
2
3companion object {
4        private const val BUNDLE_KEY_LAYOUT_HORIZONTAL_LIST_STATE = "horizontal_list_layout_manager"
5}
6
7override fun onSaveInstanceState(outState: Bundle) {
8        if (::horizontalImagesViewBinder.isInitialized) {
9            outState.putParcelable(
10                BUNDLE_KEY_LAYOUT_HORIZONTAL_LIST_STATE,
11                horizontalImagesViewBinder.recyclerViewManagerState
12            )
13        }
14        super.onSaveInstanceState(outState)
15}
16
17override fun onCreate(savedInstanceState: Bundle?) {
18        super.onCreate(savedInstanceState)
19        setContentView(R.layout.activity_main)
20
21        horizontalImagesViewBinder = HorizontalImagesListViewBinder ({ data : HorizontalImageModel ->
22            horizontalImageClick(data)}, savedInstanceState?.getParcelable(
23            BUNDLE_KEY_LAYOUT_HORIZONTAL_LIST_STATE
24        ))
25
26        addData()
27}
28
29class HorizontalImagesListViewBinder(val block : (data: HorizontalImageModel) -> Unit,
30                                     var recyclerViewManagerState: Parcelable? = null)
31    : FeedItemViewBinder<HorizontalImageListModel, HorizontalImagesListViewHolder>(
32    HorizontalImageListModel::class.java) {
33
34    override fun createViewHolder(parent: ViewGroup): HorizontalImagesListViewHolder {
35        return HorizontalImagesListViewHolder(
36            LayoutInflater.from(parent.context).inflate(getFeedItemType(), parent, false),block)
37    }
38
39    override fun bindViewHolder(model: HorizontalImageListModel, viewHolder: HorizontalImagesListViewHolder) {
40        viewHolder.bind(model,recyclerViewManagerState)
41    }
42
43    override fun getFeedItemType() = R.layout.adapter_recycleriew
44
45    override fun areContentsTheSame(oldItem: HorizontalImageListModel, newItem: HorizontalImageListModel) = oldItem == newItem
46
47    override fun areItemsTheSame(oldItem: HorizontalImageListModel, newItem: HorizontalImageListModel) : Boolean {
48        return oldItem.id == newItem.id
49    }
50
51    override fun onViewRecycled(viewHolder: HorizontalImagesListViewHolder) {
52        saveInstanceState(viewHolder)
53    }
54
55    override fun onViewDetachedFromWindow(viewHolder: HorizontalImagesListViewHolder) {
56        saveInstanceState(viewHolder)
57    }
58
59   // Saving the present instance of the recyclerview every time before the nested recyclerview is detached or the view get recycled
60    fun saveInstanceState(viewHolder: HorizontalImagesListViewHolder) {
61        if (viewHolder.adapterPosition == RecyclerView.NO_POSITION) {
62            return
63        }
64        recyclerViewManagerState = viewHolder.getLayoutManagerState()
65    }
66
67}
68
69
70class HorizontalImagesListViewHolder(val view : View, val block : (data: HorizontalImageModel) -> Unit)
71    : RecyclerView.ViewHolder(view) {
72
73    private var layoutManager: RecyclerView.LayoutManager? = null
74
75    fun bind(data: HorizontalImageListModel,layoutManagerState: Parcelable?) {
76
77        var adapter : FeedAdapter? = null
78
79        itemView.setOnClickListener {
80
81        }
82
83        itemView.apply {
84            val horizontalImagesViewBinder = HorizontalImagesViewBinder { horizontalImageModel : HorizontalImageModel ->
85                block(horizontalImageModel)}
86            val viewBinders = mutableMapOf<FeedItemClass, FeedItemBinder>()
87            @Suppress("UNCHECKED_CAST")
88            viewBinders.put(
89                horizontalImagesViewBinder.modelClass,
90                horizontalImagesViewBinder as FeedItemBinder)
91            adapter = FeedAdapter(viewBinders)
92            tv_horizontal_header?.text = data.title
93            adapter_recycllerview?.apply {
94
95                layoutManager = LinearLayoutManager(adapter_recycllerview?.context,
96                    LinearLayoutManager.HORIZONTAL,false)
97
98            }
99            layoutManager = adapter_recycllerview?.layoutManager
100            if (adapter_recycllerview?.adapter == null) {
101                adapter_recycllerview?.adapter = adapter
102            }
103            (adapter_recycllerview?.adapter as FeedAdapter).submitList(
104                data.Images as List<Any>? ?: emptyList())
105            if (layoutManagerState != null) {
106                // restoring the old instance so that scroll position is synced
107                layoutManager?.onRestoreInstanceState(layoutManagerState)
108            }
109        }
110    }
111
112    // Saving the present instance of the recyclerview
113    fun getLayoutManagerState(): Parcelable? = layoutManager?.onSaveInstanceState()
114
115}