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Fix item list scrolling down when updating data with a temporary workaround to keep until a new version of androidx paging is released with the right fix

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This commit is contained in:
Shinokuni 2019-10-19 19:13:34 +02:00
parent 36dc0cd115
commit 5c35ee3415
2 changed files with 78 additions and 1 deletions
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76
app/src/main/java/com/readrops/app/database/RoomFactoryWrapper.java Normal file
View File

@ -0,0 +1,76 @@
package com.readrops.app.database;
import androidx.annotation.NonNull;
import androidx.paging.DataSource;
import androidx.paging.PositionalDataSource;
/**
* Workaround class to avoid item recycler view scrolling down when updating data
* This class is to keep until a new version of androidx paging is released with
* bug https://issuetracker.google.com/issues/123834703 merged.
* @param <T>
*/
public class RoomFactoryWrapper<T> extends DataSource.Factory<Integer, T> {
final DataSource.Factory<Integer, T> m_wrappedFactory;
public RoomFactoryWrapper(@NonNull DataSource.Factory<Integer, T> wrappedFactory) {
m_wrappedFactory = wrappedFactory;
}
@NonNull
@Override
public DataSource<Integer, T> create() {
return new DataSourceWrapper<>((PositionalDataSource<T>) m_wrappedFactory.create());
}
public static class DataSourceWrapper<T> extends PositionalDataSource<T> {
final PositionalDataSource<T> m_wrappedSource;
DataSourceWrapper(PositionalDataSource<T> wrappedSource) {
m_wrappedSource = wrappedSource;
}
@Override
public void addInvalidatedCallback(@NonNull InvalidatedCallback onInvalidatedCallback) {
m_wrappedSource.addInvalidatedCallback(onInvalidatedCallback);
}
@Override
public void removeInvalidatedCallback(
@NonNull InvalidatedCallback onInvalidatedCallback) {
m_wrappedSource.removeInvalidatedCallback(onInvalidatedCallback);
}
@Override
public void invalidate() {
m_wrappedSource.invalidate();
}
@Override
public boolean isInvalid() {
return m_wrappedSource.isInvalid();
}
@Override
public void loadInitial(@NonNull LoadInitialParams params,
@NonNull LoadInitialCallback<T> callback) {
// Workaround for paging bug: https://issuetracker.google.com/issues/123834703
// edit initial load position to start 1/2 load ahead of requested position
int newStartPos = params.placeholdersEnabled
? params.requestedStartPosition
: Math.max(0, params.requestedStartPosition - (params.requestedLoadSize / 2));
m_wrappedSource.loadInitial(new LoadInitialParams(
newStartPos,
params.requestedLoadSize,
params.pageSize,
params.placeholdersEnabled
), callback);
}
@Override
public void loadRange(@NonNull LoadRangeParams params,
@NonNull LoadRangeCallback<T> callback) {
m_wrappedSource.loadRange(params, callback);
}
}
}

3
app/src/main/java/com/readrops/app/viewmodels/MainViewModel.java
View File

@ -12,6 +12,7 @@ import androidx.paging.PagedList;
import com.readrops.app.activities.MainActivity;
import com.readrops.app.database.Database;
import com.readrops.app.database.ItemsListQueryBuilder;
import com.readrops.app.database.RoomFactoryWrapper;
import com.readrops.app.database.entities.account.Account;
import com.readrops.app.database.entities.Feed;
import com.readrops.app.database.entities.Folder;
@ -68,7 +69,7 @@ public class MainViewModel extends AndroidViewModel {
if (lastFetch != null)
itemsWithFeed.removeSource(lastFetch);
lastFetch = new LivePagedListBuilder<>(db.itemDao().selectAll(queryBuilder.getQuery()),
lastFetch = new LivePagedListBuilder<>(new RoomFactoryWrapper<>(db.itemDao().selectAll(queryBuilder.getQuery())),
new PagedList.Config.Builder()
.setPageSize(100)
.setPrefetchDistance(150)