Fix lib for usage in GridLayoutManager

Author: Rafael Dominiquini

build.gradle

@@ -24,6 +24,6 @@ ext {
     supportLibsVersion = '23.3.0'
     targetSdkVersion = 23
     minSdkVersion = 11
-    versionCode = 15
-    versionName = "0.5.5"
+    versionCode = 16
+    versionName = "0.5.6"
 }

library/src/main/java/com/timehop/stickyheadersrecyclerview/HeaderPositionCalculator.java

@@ -75,7 +75,7 @@ public boolean hasNewHeader(int position, boolean isReverseLayout) {
       return false;
     }
 
-    int numColumns = mAdapter.getNumColumns();
+    int numColumns = mAdapter.getNumColumns() - mAdapter.getSpanSize(position) + 1;
     int columnOfItem = position % numColumns;
     if (columnOfItem > 0) {
       int firstItemOnRowPosition = position - columnOfItem;
@@ -94,6 +94,7 @@ public boolean hasNewHeader(int position, boolean isReverseLayout) {
     if (!indexOutOfBounds(nextItemPosition)){
       nextItemHeaderId = mAdapter.getHeaderId(nextItemPosition);
     }
+
     int firstItemPosition = isReverseLayout? mAdapter.getItemCount()-1 : 0;
 
     return position == firstItemPosition || headerId != nextItemHeaderId;

library/src/main/java/com/timehop/stickyheadersrecyclerview/StickyRecyclerHeadersAdapter.java

@@ -42,4 +42,12 @@ public interface StickyRecyclerHeadersAdapter<VH extends RecyclerView.ViewHolder
    * @return the number of columns
    */
   int getNumColumns();
+
+  /**
+   * Returns the number of span occupied by the item at <code>position</code>.
+   *
+   * @param position The adapter position of the item
+   * @return The number of spans occupied by the item at the provided position
+   */
+  int getSpanSize(int position);
 }

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

@@ -109,7 +109,7 @@ public void onDrawOver(Canvas canvas, RecyclerView parent, RecyclerView.State st
 
       int position = parent.getChildAdapterPosition(itemView);
 
-      if (position == RecyclerView.NO_POSITION || position % mAdapter.getNumColumns() > 0) {
+      if (position == RecyclerView.NO_POSITION || position % (mAdapter.getNumColumns() - mAdapter.getSpanSize(position) + 1) > 0) {
         continue;
       }
 

sample/src/main/java/com/timehop/stickyheadersrecyclerview/sample/MainActivity.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;
@@ -68,10 +68,17 @@ public void run() {
 
     // Set layout manager
     int orientation = getLayoutManagerOrientation(getResources().getConfiguration().orientation);
-    final StaggeredGridLayoutManager layoutManager = new StaggeredGridLayoutManager(NUM_COLUMNS, orientation);
+    final GridLayoutManager layoutManager = new GridLayoutManager(this, NUM_COLUMNS, orientation, false);
     layoutManager.setReverseLayout(isReverseButton.isChecked());
     recyclerView.setLayoutManager(layoutManager);
 
+    layoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
+      @Override
+      public int getSpanSize(int position) {
+        return adapter.getSpanSize(position);
+      }
+    });
+
     // Add the sticky headers decoration
     final StickyRecyclerHeadersDecoration headersDecor = new StickyRecyclerHeadersDecoration(adapter, true);
     recyclerView.addItemDecoration(headersDecor);
@@ -169,6 +176,7 @@ public long getHeaderId(int position) {
     @Override
     public RecyclerView.ViewHolder onCreateHeaderViewHolder(ViewGroup parent, int position) {
       View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.view_header, parent, false);
+
       return new RecyclerView.ViewHolder(view) {
       };
     }
@@ -186,13 +194,22 @@ public int getNumColumns() {
       return NUM_COLUMNS;
     }
 
+    @Override
+    public int getSpanSize(int position) {
+      return isVowel((char) getHeaderId(position)) ? NUM_COLUMNS : 1;
+    }
+
     @Override
     public void updateAdapter() {
       reorderItems();
 
       super.updateAdapter();
     }
 
+    private boolean isVowel(char c) {
+      return "AEIOUaeiou".indexOf(c) != -1;
+    }
+
     private int getRandomColor() {
       SecureRandom rgen = new SecureRandom();
       return Color.HSVToColor(150, new float[]{