Add support for SnapHelpers that display multiple items after a snap event

CircleIndicator.iml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<module external.linked.project.id="CircleIndicator" external.linked.project.path="$MODULE_DIR$" external.root.project.path="$MODULE_DIR$" external.system.id="GRADLE" type="JAVA_MODULE" version="4">
+<module external.linked.project.id="CircleIndicator" external.linked.project.path="$MODULE_DIR$" external.root.project.path="$MODULE_DIR$" external.system.id="GRADLE" external.system.module.group="" external.system.module.version="unspecified" type="JAVA_MODULE" version="4">
   <component name="FacetManager">
     <facet type="java-gradle" name="Java-Gradle">
       <configuration>

circleindicator/src/main/java/me/relex/circleindicator/CircleIndicator2.java

@@ -4,7 +4,7 @@
 import android.content.Context;
 import android.os.Build;
 import android.util.AttributeSet;
-import android.view.View;
+
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.recyclerview.widget.RecyclerView;
@@ -15,8 +15,7 @@
  */
 public class CircleIndicator2 extends BaseCircleIndicator {
 
-    private RecyclerView mRecyclerView;
-    private SnapHelper mSnapHelper;
+    private SnapIndexController mSnapIndexController;
 
     public CircleIndicator2(Context context) {
         super(context);
@@ -37,35 +36,24 @@ public CircleIndicator2(Context context, AttributeSet attrs, int defStyleAttr,
     }
 
     public void attachToRecyclerView(@NonNull RecyclerView recyclerView,
-            @NonNull SnapHelper snapHelper) {
-        mRecyclerView = recyclerView;
-        mSnapHelper = snapHelper;
+            @NonNull SnapIndexController snapIndexController) {
+        mSnapIndexController = snapIndexController;
         mLastPosition = -1;
         createIndicators();
         recyclerView.removeOnScrollListener(mInternalOnScrollListener);
         recyclerView.addOnScrollListener(mInternalOnScrollListener);
     }
 
-    private void createIndicators() {
-        RecyclerView.Adapter adapter = mRecyclerView.getAdapter();
-        int count;
-        if (adapter == null) {
-            count = 0;
-        } else {
-            count = adapter.getItemCount();
-        }
-        createIndicators(count, getSnapPosition(mRecyclerView.getLayoutManager()));
+    public void attachToRecyclerView(@NonNull RecyclerView recyclerView, @NonNull SnapHelper snapHelper) {
+        mSnapIndexController = new SimpleSnapIndexController(recyclerView, snapHelper);
+        mLastPosition = -1;
+        createIndicators();
+        recyclerView.removeOnScrollListener(mInternalOnScrollListener);
+        recyclerView.addOnScrollListener(mInternalOnScrollListener);
     }
 
-    public int getSnapPosition(@Nullable RecyclerView.LayoutManager layoutManager) {
-        if (layoutManager == null) {
-            return RecyclerView.NO_POSITION;
-        }
-        View snapView = mSnapHelper.findSnapView(layoutManager);
-        if (snapView == null) {
-            return RecyclerView.NO_POSITION;
-        }
-        return layoutManager.getPosition(snapView);
+    private void createIndicators() {
+        createIndicators(mSnapIndexController.getTotalIndicatorCount(), mSnapIndexController.getSnappedIndex());
     }
 
     private final RecyclerView.OnScrollListener mInternalOnScrollListener =
@@ -74,7 +62,7 @@ public int getSnapPosition(@Nullable RecyclerView.LayoutManager layoutManager) {
                 public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
                     super.onScrolled(recyclerView, dx, dy);
 
-                    int position = getSnapPosition(recyclerView.getLayoutManager());
+                    int position = mSnapIndexController.getSnappedIndex();
                     if (position == RecyclerView.NO_POSITION) {
                         return;
                     }
@@ -86,17 +74,13 @@ public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
             new RecyclerView.AdapterDataObserver() {
                 @Override public void onChanged() {
                     super.onChanged();
-                    if (mRecyclerView == null) {
-                        return;
-                    }
-                    RecyclerView.Adapter adapter = mRecyclerView.getAdapter();
-                    int newCount = adapter != null ? adapter.getItemCount() : 0;
+                    int newCount = mSnapIndexController.getTotalIndicatorCount();
                     int currentCount = getChildCount();
                     if (newCount == currentCount) {
                         // No change
                         return;
                     } else if (mLastPosition < newCount) {
-                        mLastPosition = getSnapPosition(mRecyclerView.getLayoutManager());
+                        mLastPosition = mSnapIndexController.getSnappedIndex();
                     } else {
                         mLastPosition = RecyclerView.NO_POSITION;
                     }

circleindicator/src/main/java/me/relex/circleindicator/SimpleSnapIndexController.java

@@ -0,0 +1,35 @@
+package me.relex.circleindicator;
+
+import android.view.View;
+
+import androidx.recyclerview.widget.RecyclerView;
+import androidx.recyclerview.widget.SnapHelper;
+
+class SimpleSnapIndexController implements SnapIndexController {
+
+    private final RecyclerView mRecyclerView;
+    private final SnapHelper mSnapHelper;
+
+    public SimpleSnapIndexController(RecyclerView recyclerView, SnapHelper snapHelper) {
+        mRecyclerView = recyclerView;
+        mSnapHelper = snapHelper;
+    }
+
+    @Override
+    public int getSnappedIndex() {
+        RecyclerView.LayoutManager layoutManager = mRecyclerView.getLayoutManager();
+        if (layoutManager == null) return RecyclerView.NO_POSITION;
+
+        final View snapView = mSnapHelper.findSnapView(layoutManager);
+        if (snapView == null) return RecyclerView.NO_POSITION;
+
+        return layoutManager.getPosition(snapView);
+    }
+
+    @Override
+    public int getTotalIndicatorCount() {
+        final RecyclerView.Adapter adapter = mRecyclerView.getAdapter();
+        if (adapter == null) return 0;
+        return adapter.getItemCount();
+    }
+}

circleindicator/src/main/java/me/relex/circleindicator/SnapIndexController.java

@@ -0,0 +1,6 @@
+package me.relex.circleindicator;
+
+public interface SnapIndexController {
+    int getSnappedIndex();
+    int getTotalIndicatorCount();
+}