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ContactsViewModel.kt
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ContactsViewModel.kt
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package com.moldedbits.pagedlistdemo.ui.contact
import android.arch.lifecycle.LiveData
import android.arch.lifecycle.ViewModel
import android.arch.paging.DataSource
import android.arch.paging.LivePagedListBuilder
import android.arch.paging.PagedList
import android.arch.paging.PositionalDataSource
import android.content.ContentResolver
import android.provider.ContactsContract
import com.moldedbits.pagedlistdemo.data.Contact
class ContactsViewModel(private val contentResolver: ContentResolver) : ViewModel() {
lateinit var contactsList: LiveData<PagedList<Contact>>
fun loadContacts() {
val config = PagedList.Config.Builder()
.setPageSize(20)
.setEnablePlaceholders(false)
.build()
contactsList = LivePagedListBuilder<Int, Contact>(
ContactsDataSourceFactory(contentResolver), config).build()
}
}
class ContactsDataSourceFactory(private val contentResolver: ContentResolver) :
DataSource.Factory<Int, Contact>() {
override fun create(): DataSource<Int, Contact> {
return ContactsDataSource(contentResolver)
}
}
class ContactsDataSource(private val contentResolver: ContentResolver) :
PositionalDataSource<Contact>() {
companion object {
private val PROJECTION = arrayOf(
ContactsContract.Contacts._ID,
ContactsContract.Contacts.LOOKUP_KEY,
ContactsContract.Contacts.DISPLAY_NAME_PRIMARY
)
}
override fun loadInitial(params: LoadInitialParams, callback: LoadInitialCallback<Contact>) {
callback.onResult(getContacts(params.requestedLoadSize, params.requestedStartPosition), 0)
}
override fun loadRange(params: LoadRangeParams, callback: LoadRangeCallback<Contact>) {
callback.onResult(getContacts(params.loadSize, params.startPosition))
}
private fun getContacts(limit: Int, offset: Int): MutableList<Contact> {
val cursor = contentResolver.query(ContactsContract.Contacts.CONTENT_URI,
PROJECTION,
null,
null,
ContactsContract.Contacts.DISPLAY_NAME_PRIMARY +
" ASC LIMIT " + limit + " OFFSET " + offset)
cursor.moveToFirst()
val contacts: MutableList<Contact> = mutableListOf()
while (!cursor.isAfterLast) {
val id = cursor.getLong(cursor.getColumnIndex(PROJECTION[0]))
val lookupKey = cursor.getString(cursor.getColumnIndex(PROJECTION[0]))
val name = cursor.getString(cursor.getColumnIndex(PROJECTION[2]))
contacts.add(Contact(id, lookupKey, name))
cursor.moveToNext()
}
cursor.close()
return contacts
}
}