For SDK 10, smaller clip area for headers

library/src/main/java/com/timehop/stickyheadersrecyclerview/rendering/HeaderRenderer.java

@@ -39,9 +39,11 @@ private HeaderRenderer(OrientationProvider orientationProvider,
   public void drawHeader(RecyclerView recyclerView, Canvas canvas, View header, Rect offset) {
     canvas.save();
 
-    if (recyclerView.getLayoutManager().getClipToPadding()) {
+    // For sdk < 14 need to clip regardless because of full screen
+    // header strangeness
+    if (Build.VERSION.SDK_INT < 14 || recyclerView.getLayoutManager().getClipToPadding()) {
       // Clip drawing of headers to the padding of the RecyclerView. Avoids drawing in the padding
-      Rect clipRect = getClipRectForHeader(recyclerView, header);
+      Rect clipRect = getClipRectForHeader(recyclerView, header, offset);
       canvas.clipRect(clipRect);
     }
 
@@ -51,7 +53,7 @@ public void drawHeader(RecyclerView recyclerView, Canvas canvas, View header, Re
     canvas.restore();
   }
 
-  /**
+   /**
    * Gets a clipping rect for the header based on the margins of the header and the padding of the
    * recycler.
    * FIXME: Currently right margin in VERTICAL orientation and bottom margin in HORIZONTAL
@@ -60,23 +62,100 @@ public void drawHeader(RecyclerView recyclerView, Canvas canvas, View header, Re
    *
    * @param recyclerView for which to provide a header
    * @param header       for clipping
+   * @param offset       for clipping specific view offset rather than entire recyclerview
    * @return a {@link Rect} for clipping a provided header to the padding of a recycler view
    */
-  private Rect getClipRectForHeader(RecyclerView recyclerView, View header) {
+  private Rect getClipRectForHeader(RecyclerView recyclerView, View header, Rect offset) {
     Rect headerMargins = mDimensionCalculator.getMargins(header);
-    if (mOrientationProvider.getOrientation(recyclerView) == LinearLayout.VERTICAL) {
-      return new Rect(
-          recyclerView.getPaddingLeft(),
-          recyclerView.getPaddingTop(),
-          recyclerView.getWidth() - recyclerView.getPaddingRight() - headerMargins.right,
-          recyclerView.getHeight() - recyclerView.getPaddingBottom());
+
+    // If sdk > 14 clip to recyclerview (What it was doing previously)
+    if (Build.VERSION.SDK_INT > 14) {
+      if (mOrientationProvider.getOrientation(recyclerView) == LinearLayout.VERTICAL) {
+        return new Rect(
+              recyclerView.getPaddingLeft(),
+              recyclerView.getPaddingTop(),
+              recyclerView.getWidth() - recyclerView.getPaddingRight() - headerMargins.right,
+              recyclerView.getHeight() - recyclerView.getPaddingBottom());
+      } else {
+        return new Rect(
+              recyclerView.getPaddingLeft(),
+              recyclerView.getPaddingTop(),
+              recyclerView.getWidth() - recyclerView.getPaddingRight(),
+              recyclerView.getHeight() - recyclerView.getPaddingBottom() - headerMargins.bottom);
+      }
+    // If sdk < 14, do clipping which clips based on exact header size
+    //and offset, instead of full size of recyclerview
     } else {
-      return new Rect(
-          recyclerView.getPaddingLeft(),
-          recyclerView.getPaddingTop(),
-          recyclerView.getWidth() - recyclerView.getPaddingRight(),
-          recyclerView.getHeight() - recyclerView.getPaddingBottom() - headerMargins.bottom);
+      if (mOrientationProvider.getOrientation(recyclerView) == LinearLayout.VERTICAL) {
+
+        int offsetBottom = offset.top + header.getHeight();
+        int recyclerBottom = recyclerView.getHeight() - recyclerView.getPaddingBottom();
+
+        // If offsets are above or below no need for visibility
+        if (offset.top <= recyclerView.getPaddingTop() && offsetBottom <= recyclerView.getPaddingTop()
+                || offsetBottom >= recyclerBottom && offset.top >= recyclerBottom) {
+            return new Rect(0, 0, 0, 0);
+
+        // If topOffset within top padding and bottomOffset NOT within top padding
+        } else if (offset.top < recyclerView.getPaddingTop() && offsetBottom > recyclerView.getPaddingTop()) {
+                return new Rect(
+                        recyclerView.getPaddingLeft(),
+                        recyclerView.getPaddingTop(),
+                        recyclerView.getWidth() - recyclerView.getPaddingRight() - headerMargins.right,
+                        offsetBottom);
+
+        // If offsetBottom within bottom padding and offsetTop NOT within bottom padding
+        } else if (offsetBottom > recyclerBottom && offset.top < recyclerBottom) {
+            return new Rect(
+                    recyclerView.getPaddingLeft(),
+                    offset.top,
+                    recyclerView.getWidth() - recyclerView.getPaddingRight() - headerMargins.right,
+                    recyclerBottom);
+
+        // Else use offset for all clips
+        } else {
+            return new Rect(
+                    recyclerView.getPaddingLeft(),
+                    offset.top,
+                    recyclerView.getWidth() - recyclerView.getPaddingRight() - headerMargins.right,
+                    offset.top + header.getHeight());
+        }
+
+      } else {
+
+        int offsetRight = offset.left + header.getWidth();
+        int recyclerRight = recyclerView.getWidth() - recyclerView.getPaddingRight();
+
+         // If offsets are both to right or left, no need for visibility
+        if (offset.left <= recyclerView.getPaddingLeft() && offsetRight <= recyclerView.getPaddingLeft()
+                || offsetRight >= recyclerRight && offset.left >= recyclerRight) {
+            return new Rect(0, 0, 0, 0);
+
+        // If offsetLeft within paddingLeft and offsetRight NOT within paddingLeft
+        } else if (offset.left < recyclerView.getPaddingLeft() && offsetRight > recyclerView.getPaddingLeft()) {
+            return new Rect(
+                    recyclerView.getPaddingLeft(),
+                    recyclerView.getPaddingTop(),
+                    offsetRight,
+                    recyclerView.getHeight() - recyclerView.getPaddingBottom() - headerMargins.bottom);
+
+        // If offsetRight within paddingRight and offsetLeft NOT within paddingRight
+        } else if (offsetRight > recyclerRight && offset.left < recyclerRight) {
+            return new Rect(
+                    offset.left,
+                    recyclerView.getPaddingTop(),
+                    recyclerView.getWidth() - recyclerView.getPaddingRight(),
+                    recyclerView.getHeight() - recyclerView.getPaddingBottom()- headerMargins.bottom);
+
+        // Else use offset for all clips
+        } else {
+            return new Rect(
+                    offset.left,
+                    recyclerView.getPaddingTop(),
+                    offsetRight,
+                    recyclerView.getHeight() - recyclerView.getPaddingBottom() - headerMargins.bottom);
+        }
+      }
     }
   }
-
 }