ability to disable syicky headers.

Author: Dominiquini

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

@@ -110,11 +110,11 @@ public boolean headerObscuringSomeItem(RecyclerView parent, View firstHeader) {
         return false;
     }
 
-    public void initHeaderBounds(Rect bounds, RecyclerView recyclerView, View header, View firstView, boolean firstHeader) {
+    public void initHeaderBounds(Rect bounds, RecyclerView recyclerView, View header, View firstView, boolean firstHeader, boolean enableStickyHeader) {
         int orientation = mOrientationProvider.getOrientation(recyclerView);
-        initDefaultHeaderOffset(bounds, recyclerView, header, firstView, orientation);
+        initDefaultHeaderOffset(bounds, recyclerView, header, firstView, orientation, enableStickyHeader);
 
-        if (firstHeader && isStickyHeaderBeingPushedOffscreen(recyclerView, header)) {
+        if (enableStickyHeader && firstHeader && isStickyHeaderBeingPushedOffscreen(recyclerView, header)) {
             View viewAfterNextHeader = getFirstViewUnobscuredByHeader(recyclerView, header);
             int firstViewUnderHeaderPosition = recyclerView.getChildAdapterPosition(viewAfterNextHeader);
             View secondHeader = mHeaderProvider.getHeader(recyclerView, firstViewUnderHeaderPosition);
@@ -123,19 +123,19 @@ public void initHeaderBounds(Rect bounds, RecyclerView recyclerView, View header
         }
     }
 
-    private void initDefaultHeaderOffset(Rect headerMargins, RecyclerView recyclerView, View header, View firstView, int orientation) {
+    private void initDefaultHeaderOffset(Rect headerMargins, RecyclerView recyclerView, View header, View firstView, int orientation, boolean enableStickyHeader) {
         int translationX, translationY;
         mDimensionCalculator.initMargins(mTempRect1, header);
         if (orientation == LinearLayoutManager.VERTICAL) {
             translationX = firstView.getLeft() + mTempRect1.left;
-            translationY = Math.max(
-                    firstView.getTop() - header.getHeight() - mTempRect1.bottom,
-                    getListTop(recyclerView) + mTempRect1.top);
+            translationY = enableStickyHeader ?
+                    Math.max(firstView.getTop() - header.getHeight() - mTempRect1.bottom, getListTop(recyclerView) + mTempRect1.top) :
+                    firstView.getTop() - header.getHeight() - mTempRect1.bottom;
         } else {
             translationY = firstView.getTop() + mTempRect1.top;
-            translationX = Math.max(
-                    firstView.getLeft() - header.getWidth() - mTempRect1.right,
-                    getListLeft(recyclerView) + mTempRect1.left);
+            translationX = enableStickyHeader ?
+                    Math.max(firstView.getLeft() - header.getWidth() - mTempRect1.right, getListLeft(recyclerView) + mTempRect1.left) :
+                    firstView.getLeft() - header.getWidth() - mTempRect1.right;
         }
 
         headerMargins.set(translationX, translationY, translationX + header.getWidth(),

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

@@ -23,13 +23,17 @@ public class StickyRecyclerHeadersDecoration extends RecyclerView.ItemDecoration
     private final HeaderPositionCalculator mHeaderPositionCalculator;
     private final HeaderRenderer mRenderer;
     private final DimensionCalculator mDimensionCalculator;
+
     /**
      * The following field is used as a buffer for internal calculations. Its sole purpose is to avoid
      * allocating new Rect every time we need one.
      */
     private final Rect mTempRect = new Rect();
+
     private StickyRecyclerHeadersPositionChangeListener mHeaderListener;
 
+    private boolean mEnableStickyHeader = true;
+
     // TODO: Consider passing in orientation to simplify orientation accounting within calculation
     public StickyRecyclerHeadersDecoration(StickyRecyclerHeadersAdapter adapter) {
         this(adapter, new LinearLayoutOrientationProvider(), new DimensionCalculator());
@@ -113,10 +117,11 @@ public void onDrawOver(Canvas canvas, RecyclerView parent, RecyclerView.State st
                     headerOffset = new Rect();
                     mHeaderRects.put(position, headerOffset);
                 }
-                mHeaderPositionCalculator.initHeaderBounds(headerOffset, parent, header, itemView, hasStickyHeader);
+
+                mHeaderPositionCalculator.initHeaderBounds(headerOffset, parent, header, itemView, hasStickyHeader, mEnableStickyHeader);
                 mRenderer.drawHeader(parent, canvas, header, headerOffset);
 
-                if (mHeaderListener != null) {
+                if (mEnableStickyHeader && mHeaderListener != null) {
                     mHeaderListener.onHeaderPositionChanged(mAdapter.getHeaderId(position), header, position, headerOffset);
                 }
             }
@@ -170,6 +175,14 @@ public void invalidateHeaders() {
         mHeaderProvider.invalidate();
     }
 
+    public void enableStickyHeaders(boolean enableStickyHeaders) {
+        this.mEnableStickyHeader = enableStickyHeaders;
+    }
+
+    public boolean isStickyHeadersEnabled() {
+        return this.mEnableStickyHeader;
+    }
+
     public void setHeaderPositionListener(StickyRecyclerHeadersPositionChangeListener headerListener) {
         this.mHeaderListener = headerListener;
     }