provide event for detecting "required scroll", 0.9.4

Team-SOFTsk · Jun 9, 2017 · 615278c · 615278c
1 parent 527791d
commit 615278c
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Showing 2 changed files with 34 additions and 4 deletions.
diff --git a/gradle.properties b/gradle.properties
@@ -17,7 +17,7 @@ org.gradle.jvmargs=-Xmx1536m
 # org.gradle.parallel=true
 
 POM_PACKAGING=aar
-VERSION_NAME=0.9.3
+VERSION_NAME=0.9.4
 VERSION_CODE=1
 GROUP=sk.teamsoft
 ORGANIZATION_NAME=team-softsk

diff --git a/observablecollection/src/main/java/sk/teamsoft/observablecollection/ObservableAdapter.java b/observablecollection/src/main/java/sk/teamsoft/observablecollection/ObservableAdapter.java
@@ -3,6 +3,7 @@
 import android.content.res.Resources;
 import android.support.annotation.Nullable;
 import android.support.v7.util.DiffUtil;
+import android.support.v7.util.ListUpdateCallback;
 import android.support.v7.widget.RecyclerView;
 import android.view.InflateException;
 import android.view.LayoutInflater;
@@ -37,6 +38,7 @@ public class ObservableAdapter<T> extends RecyclerView.Adapter<ObservableAdapter
 
     private final AdapterSource<T> source;
     private final PublishSubject<ViewEvent> itemEvent = PublishSubject.create();
+    private final PublishSubject<Boolean> requestScrollEvent = PublishSubject.create();
     private final CompositeDisposable changeWatcher = new CompositeDisposable();
 
     public ObservableAdapter(AdapterSource<T> source) {
@@ -80,6 +82,13 @@ public ObservableAdapter(AdapterSource<T> source) {
                 .subscribe(new Consumer<DiffUtil.DiffResult>() {
                                @Override
                                public void accept(@NonNull DiffUtil.DiffResult diffResult) throws Exception {
+                                   diffResult.dispatchUpdatesTo(new SimpleUpdateCallback() {
+                                       @Override public void onInserted(int position, int count) {
+                                           if (position == 0) {
+                                               requestScrollEvent.onNext(Boolean.TRUE);
+                                           }
+                                       }
+                                   });
                                    diffResult.dispatchUpdatesTo(ObservableAdapter.this);
                                }
                            },
@@ -138,9 +147,6 @@ public void accept(@NonNull Throwable throwable) throws Exception {
                             Timber.e(throwable, "Error:viewHolder:event");
                         }
                     });
-        } else {
-            Timber.v("onAttached:noObservable");
-            //TODO check if we need to dispose observable if there was any
         }
     }
 
@@ -154,6 +160,16 @@ public void accept(@NonNull Throwable throwable) throws Exception {
         super.onViewRecycled(holder);
     }
 
+    /**
+     * Notify that list inserted new items in front of the existing collection
+     * You can use this to detect when you need to force list to scroll up (i.e. when list
+     * was scrolled to the top, and UI maintained scroll position after collection was updated)
+     * @return observable event
+     */
+    public Observable<Boolean> onRequestScrollUp() {
+        return requestScrollEvent;
+    }
+
     /**
      * Generic method which dispatches viewHolder events (click, longtap, whatever) to
      * the listeners (typically presenters).
@@ -260,4 +276,18 @@ public Object getData() {
                     '}';
         }
     }
+
+    /**
+     * Helper class for better readability
+     */
+    static class SimpleUpdateCallback implements ListUpdateCallback {
+
+        @Override public void onInserted(int position, int count) {}
+
+        @Override public void onRemoved(int position, int count) {}
+
+        @Override public void onMoved(int fromPosition, int toPosition) {}
+
+        @Override public void onChanged(int position, int count, Object payload) {}
+    }
 }