ability to disable syicky headers

Author: Rafael 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);
@@ -123,7 +123,7 @@ 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);
 
@@ -138,18 +138,17 @@ private void initDefaultHeaderOffset(Rect headerMargins, RecyclerView recyclerVi
 
     if (orientation == LinearLayoutManager.VERTICAL) {
       translationX = firstView.getLeft() - leftMargin + mTempRect1.left;
-      translationY = Math.max(
-          firstView.getTop() - topMargin - header.getHeight() - mTempRect1.bottom,
-          getListTop(recyclerView) + mTempRect1.top);
+      translationY =  enableStickyHeader ?
+              Math.max(firstView.getTop() - topMargin - header.getHeight() - mTempRect1.bottom, getListTop(recyclerView) + mTempRect1.top) :
+              firstView.getTop() - topMargin - header.getHeight() - mTempRect1.bottom;
     } else {
       translationY = firstView.getTop() - topMargin + mTempRect1.top;
-      translationX = Math.max(
-          firstView.getLeft() - leftMargin - header.getWidth() - mTempRect1.right,
-          getListLeft(recyclerView) + mTempRect1.left);
+      translationX = enableStickyHeader ?
+              Math.max(firstView.getLeft() - leftMargin - header.getWidth() - mTempRect1.right, getListLeft(recyclerView) + mTempRect1.left) :
+              firstView.getLeft() - leftMargin - header.getWidth() - mTempRect1.right;
     }
 
-    headerMargins.set(translationX, translationY, translationX + header.getWidth(),
-            translationY + header.getHeight());
+    headerMargins.set(translationX, translationY, translationX + header.getWidth(), translationY + header.getHeight());
   }
 
   private boolean isStickyHeaderBeingPushedOffscreen(RecyclerView recyclerView, View stickyHeader) {

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

@@ -25,45 +25,50 @@ public class StickyRecyclerHeadersDecoration extends RecyclerView.ItemDecoration
   private final HeaderRenderer mRenderer;
   private final DimensionCalculator mDimensionCalculator;
   private StickyRecyclerHeadersPositionChangeListener mHeaderListener;
+  private boolean mEnableStickyHeader = true;
 
   /**
    * 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();
 
-  // TODO: Consider passing in orientation to simplify orientation accounting within calculation
   public StickyRecyclerHeadersDecoration(StickyRecyclerHeadersAdapter adapter) {
-    this(adapter, new LinearLayoutOrientationProvider(), new DimensionCalculator(), null);
+    this(adapter, new LinearLayoutOrientationProvider(), new DimensionCalculator(), null, true);
   }
 
-  public StickyRecyclerHeadersDecoration(StickyRecyclerHeadersAdapter adapter, ItemVisibilityAdapter visibilityAdapter) {
-    this(adapter, new LinearLayoutOrientationProvider(), new DimensionCalculator(), visibilityAdapter);
+  public StickyRecyclerHeadersDecoration(StickyRecyclerHeadersAdapter adapter, boolean enableStickyHeader) {
+    this(adapter, new LinearLayoutOrientationProvider(), new DimensionCalculator(), null, enableStickyHeader);
+  }
+
+  public StickyRecyclerHeadersDecoration(StickyRecyclerHeadersAdapter adapter, ItemVisibilityAdapter visibilityAdapter, boolean enableStickyHeader) {
+    this(adapter, new LinearLayoutOrientationProvider(), new DimensionCalculator(), visibilityAdapter, enableStickyHeader);
   }
 
   private StickyRecyclerHeadersDecoration(StickyRecyclerHeadersAdapter adapter, OrientationProvider orientationProvider,
-      DimensionCalculator dimensionCalculator, ItemVisibilityAdapter visibilityAdapter) {
+      DimensionCalculator dimensionCalculator, ItemVisibilityAdapter visibilityAdapter, boolean enableStickyHeader) {
     this(adapter, orientationProvider, dimensionCalculator, new HeaderRenderer(orientationProvider),
-        new HeaderViewCache(adapter, orientationProvider), visibilityAdapter);
+        new HeaderViewCache(adapter, orientationProvider), visibilityAdapter, enableStickyHeader);
   }
 
   private StickyRecyclerHeadersDecoration(StickyRecyclerHeadersAdapter adapter, OrientationProvider orientationProvider,
-      DimensionCalculator dimensionCalculator, HeaderRenderer headerRenderer, HeaderProvider headerProvider, ItemVisibilityAdapter visibilityAdapter) {
+      DimensionCalculator dimensionCalculator, HeaderRenderer headerRenderer, HeaderProvider headerProvider, ItemVisibilityAdapter visibilityAdapter, boolean enableStickyHeader) {
     this(adapter, headerRenderer, orientationProvider, dimensionCalculator, headerProvider,
         new HeaderPositionCalculator(adapter, headerProvider, orientationProvider,
-            dimensionCalculator), visibilityAdapter);
+            dimensionCalculator), visibilityAdapter, enableStickyHeader);
   }
 
   private StickyRecyclerHeadersDecoration(StickyRecyclerHeadersAdapter adapter, HeaderRenderer headerRenderer,
       OrientationProvider orientationProvider, DimensionCalculator dimensionCalculator, HeaderProvider headerProvider,
-      HeaderPositionCalculator headerPositionCalculator, ItemVisibilityAdapter visibilityAdapter) {
+      HeaderPositionCalculator headerPositionCalculator, ItemVisibilityAdapter visibilityAdapter, boolean enableStickyHeader) {
     mAdapter = adapter;
     mHeaderProvider = headerProvider;
     mOrientationProvider = orientationProvider;
     mRenderer = headerRenderer;
     mDimensionCalculator = dimensionCalculator;
     mHeaderPositionCalculator = headerPositionCalculator;
     mVisibilityAdapter = visibilityAdapter;
+    mEnableStickyHeader = enableStickyHeader;
   }
 
   @Override
@@ -120,10 +125,10 @@ 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(this, mAdapter.getHeaderId(position), header, position, headerOffset);
         }
       }
@@ -184,4 +189,12 @@ public void invalidateHeaders() {
   public void setHeaderPositionListener(StickyRecyclerHeadersPositionChangeListener headerListener) {
     this.mHeaderListener = headerListener;
   }
+
+  public void enableStickyHeaders(boolean enableStickyHeaders) {
+    this.mEnableStickyHeader = enableStickyHeaders;
+  }
+
+  public boolean isStickyHeadersEnabled() {
+    return this.mEnableStickyHeader;
+  }
 }

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

@@ -66,7 +66,7 @@ public void run() {
     recyclerView.setLayoutManager(layoutManager);
 
     // Add the sticky headers decoration
-    final StickyRecyclerHeadersDecoration headersDecor = new StickyRecyclerHeadersDecoration(adapter);
+    final StickyRecyclerHeadersDecoration headersDecor = new StickyRecyclerHeadersDecoration(adapter, true);
     recyclerView.addItemDecoration(headersDecor);
 
     headersDecor.setHeaderPositionListener(new StickyRecyclerHeadersPositionChangeListener() {

sample/src/main/res/layout-land/view_header.xml

@@ -23,6 +23,7 @@
         android:layout_width="4dp"
         android:layout_height="match_parent"
         android:alpha="0.64"
-        android:background="@drawable/shadow_vertical" />
+        android:background="@drawable/shadow_vertical"
+        android:visibility="invisible" />
 
 </LinearLayout>

sample/src/main/res/layout/view_header.xml

@@ -23,6 +23,7 @@
         android:layout_width="wrap_content"
         android:layout_height="4dp"
         android:alpha="0.64"
-        android:background="@drawable/shadow_horizontal" />
+        android:background="@drawable/shadow_horizontal"
+        android:visibility="invisible" />
 
 </LinearLayout>