106 lines
3.9 KiB
Kotlin
106 lines
3.9 KiB
Kotlin
package org.pixeldroid.app.posts.feeds.cachedFeeds
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import android.os.Bundle
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import android.view.LayoutInflater
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import android.view.View
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import android.view.ViewGroup
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import androidx.lifecycle.ViewModel
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import androidx.lifecycle.ViewModelProvider
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import androidx.lifecycle.lifecycleScope
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import androidx.paging.*
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import androidx.paging.LoadState.*
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import androidx.recyclerview.widget.LinearLayoutManager
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import androidx.recyclerview.widget.RecyclerView
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import kotlinx.coroutines.Job
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import kotlinx.coroutines.flow.*
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import org.pixeldroid.app.databinding.FragmentFeedBinding
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import org.pixeldroid.app.posts.feeds.initAdapter
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import org.pixeldroid.app.utils.BaseFragment
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import org.pixeldroid.app.utils.api.objects.FeedContentDatabase
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import org.pixeldroid.app.utils.db.AppDatabase
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import org.pixeldroid.app.utils.db.dao.feedContent.FeedContentDao
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import org.pixeldroid.app.utils.limitedLengthSmoothScrollToPosition
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/**
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* A fragment representing a list of [FeedContentDatabase] items that are cached by the database.
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*/
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open class CachedFeedFragment<T: FeedContentDatabase> : BaseFragment() {
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internal lateinit var viewModel: FeedViewModel<T>
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internal lateinit var adapter: PagingDataAdapter<T, RecyclerView.ViewHolder>
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private lateinit var binding: FragmentFeedBinding
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private var job: Job? = null
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@ExperimentalPagingApi
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internal fun launch() {
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// Make sure we cancel the previous job before creating a new one
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job?.cancel()
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job = lifecycleScope.launchWhenStarted {
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viewModel.flow.collectLatest {
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adapter.submitData(it)
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}
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}
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}
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internal fun initSearch() {
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// Scroll to top when the list is refreshed from network.
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lifecycleScope.launchWhenStarted {
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adapter.loadStateFlow
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// Only emit when REFRESH LoadState for RemoteMediator changes.
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.distinctUntilChangedBy {
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it.refresh
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}
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// Only react to cases where Remote REFRESH completes i.e., NotLoading.
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.filter { it.refresh is NotLoading}
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.collect { binding.list.scrollToPosition(0) }
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}
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}
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override fun onCreateView(
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inflater: LayoutInflater, container: ViewGroup?,
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savedInstanceState: Bundle?
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): View? {
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super.onCreateView(inflater, container, savedInstanceState)
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binding = FragmentFeedBinding.inflate(layoutInflater)
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initAdapter(binding.progressBar, binding.swipeRefreshLayout,
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binding.list, binding.motionLayout, binding.errorLayout, adapter)
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binding.swipeRefreshLayout.setOnRefreshListener {
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adapter.refresh()
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}
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return binding.root
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}
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fun onTabReClicked() {
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binding.list.limitedLengthSmoothScrollToPosition(0)
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}
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}
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/**
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* Factory that creates ViewModel from a [FeedContentRepository], to be used in cached feeds to
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* fetch the ViewModel that is responsible for preparing and managing the data
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* for a CachedFeedFragment
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*/
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class ViewModelFactory<U: FeedContentDatabase> @ExperimentalPagingApi constructor(private val db: AppDatabase?,
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private val dao: FeedContentDao<U>?,
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private val remoteMediator: RemoteMediator<Int, U>?,
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private val feedContentRepository: FeedContentRepository<U> = FeedContentRepository(db!!, dao!!, remoteMediator!!)
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) : ViewModelProvider.Factory {
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override fun <T : ViewModel> create(modelClass: Class<T>): T {
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if (modelClass.isAssignableFrom(FeedViewModel::class.java)) {
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@Suppress("UNCHECKED_CAST")
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return FeedViewModel(feedContentRepository) as T
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}
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throw IllegalArgumentException("Unknown ViewModel class")
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}
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} |