Allowing StaggeredGridLayoutManager

Author: Rafael Dominiquini

library/src/main/java/com/timehop/stickyheadersrecyclerview/decorators/StickyRecyclerHeadersDecoration.java

@@ -15,7 +15,7 @@
 import com.timehop.stickyheadersrecyclerview.caching.HeaderViewCache;
 import com.timehop.stickyheadersrecyclerview.calculation.DimensionCalculator;
 import com.timehop.stickyheadersrecyclerview.rendering.HeaderRenderer;
-import com.timehop.stickyheadersrecyclerview.util.LinearLayoutOrientationProvider;
+import com.timehop.stickyheadersrecyclerview.util.LayoutManagerOrientationProvider;
 import com.timehop.stickyheadersrecyclerview.util.OrientationProvider;
 
 public class StickyRecyclerHeadersDecoration extends RecyclerView.ItemDecoration {
@@ -39,11 +39,11 @@ public class StickyRecyclerHeadersDecoration extends RecyclerView.ItemDecoration
   private final Rect mTempRect = new Rect();
 
   public StickyRecyclerHeadersDecoration(StickyRecyclerHeadersAdapter adapter) {
-    this(adapter, new LinearLayoutOrientationProvider(), new DimensionCalculator(), true);
+    this(adapter, new LayoutManagerOrientationProvider(), new DimensionCalculator(), true);
   }
 
   public StickyRecyclerHeadersDecoration(StickyRecyclerHeadersAdapter adapter, boolean enableStickyHeader) {
-    this(adapter, new LinearLayoutOrientationProvider(), new DimensionCalculator(), enableStickyHeader);
+    this(adapter, new LayoutManagerOrientationProvider(), new DimensionCalculator(), enableStickyHeader);
   }
 
   private StickyRecyclerHeadersDecoration(StickyRecyclerHeadersAdapter adapter, OrientationProvider orientationProvider, DimensionCalculator dimensionCalculator, boolean enableStickyHeader) {

library/src/main/java/com/timehop/stickyheadersrecyclerview/util/LayoutManagerOrientationProvider.java

@@ -0,0 +1,43 @@
+package com.timehop.stickyheadersrecyclerview.util;
+
+import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.StaggeredGridLayoutManager;
+
+/**
+ * OrientationProvider for ReyclerViews who use a LayoutManager
+ */
+public class LayoutManagerOrientationProvider implements OrientationProvider {
+
+  public static int getRecyclerViewOrientation(RecyclerView recyclerView) {
+    RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
+    if (layoutManager instanceof LinearLayoutManager) {
+      return ((LinearLayoutManager) layoutManager).getOrientation();
+    } else if (layoutManager instanceof StaggeredGridLayoutManager) {
+      return ((StaggeredGridLayoutManager) layoutManager).getOrientation();
+    } else {
+      throw new IllegalStateException("DividerDecoration can only be used with a valid LayoutManager: " + layoutManager.getClass().getSimpleName());
+    }
+  }
+
+  public boolean isRecyclerViewReverseLayout(RecyclerView recyclerView) {
+    RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
+    if (layoutManager instanceof LinearLayoutManager) {
+      return ((LinearLayoutManager) layoutManager).getReverseLayout();
+    } else if (layoutManager instanceof StaggeredGridLayoutManager) {
+      return ((StaggeredGridLayoutManager) layoutManager).getReverseLayout();
+    } else {
+      throw new IllegalStateException("DividerDecoration can only be used with a valid LayoutManager: " + layoutManager.getClass().getSimpleName());
+    }
+  }
+
+  @Override
+  public int getOrientation(RecyclerView recyclerView) {
+    return getRecyclerViewOrientation(recyclerView);
+  }
+
+  @Override
+  public boolean isReverseLayout(RecyclerView recyclerView) {
+    return isRecyclerViewReverseLayout(recyclerView);
+  }
+}

library/src/main/java/com/timehop/stickyheadersrecyclerview/util/LinearLayoutOrientationProvider.java

@@ -9,6 +9,8 @@
 import android.support.v7.widget.RecyclerView;
 import android.view.View;
 
+import com.timehop.stickyheadersrecyclerview.util.LayoutManagerOrientationProvider;
+
 
 public class DividerDecoration extends RecyclerView.ItemDecoration {
 
@@ -29,14 +31,7 @@ public DividerDecoration(Context context) {
   }
 
   private int getOrientation(RecyclerView parent) {
-    LinearLayoutManager layoutManager;
-    try {
-      layoutManager = (LinearLayoutManager) parent.getLayoutManager();
-    } catch (ClassCastException e) {
-      throw new IllegalStateException("DividerDecoration can only be used with a " +
-          "LinearLayoutManager.", e);
-    }
-    return layoutManager.getOrientation();
+    return LayoutManagerOrientationProvider.getRecyclerViewOrientation(parent);
   }
 
   @Override
@@ -58,8 +53,7 @@ public void drawVertical(Canvas c, RecyclerView parent) {
     final int childCount = parent.getChildCount();
     for (int i = 0; i < childCount; i++) {
       final View child = parent.getChildAt(i);
-      final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
-          .getLayoutParams();
+      final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
       final int top = Math.max(recyclerViewTop, child.getBottom() + params.bottomMargin);
       final int bottom = Math.min(recyclerViewBottom, top + mDivider.getIntrinsicHeight());
       mDivider.setBounds(left, top, right, bottom);

sample/src/main/java/com/timehop/stickyheadersrecyclerview/sample/DividerDecoration.java

@@ -8,9 +8,9 @@
 import android.os.Handler;
 import android.os.Looper;
 import android.support.v7.app.AppCompatActivity;
-import android.support.v7.widget.GridLayoutManager;
 import android.support.v7.widget.LinearLayoutManager;
 import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.StaggeredGridLayoutManager;
 import android.text.TextUtils;
 import android.util.Log;
 import android.view.LayoutInflater;
@@ -68,7 +68,8 @@ public void run() {
 
     // Set layout manager
     int orientation = getLayoutManagerOrientation(getResources().getConfiguration().orientation);
-    final GridLayoutManager layoutManager = new GridLayoutManager(this, NUM_COLUMNS, orientation, isReverseButton.isChecked());
+    final StaggeredGridLayoutManager layoutManager = new StaggeredGridLayoutManager(NUM_COLUMNS, orientation);
+    layoutManager.setReverseLayout(isReverseButton.isChecked());
     recyclerView.setLayoutManager(layoutManager);
 
     // Add the sticky headers decoration