Adding elevation to NTP snippets

chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetItemDecoration.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetItemDecoration.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetItemDecoration.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetItemDecoration.java
index 696036fcc2ce490dbe90aca1700db33194e3007d..62255aa4ca8c963a05f26826aae62cd4df065581 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetItemDecoration.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetItemDecoration.java
@@ -4,73 +4,49 @@
 
 package org.chromium.chrome.browser.ntp.snippets;
 
-import android.content.Context;
-import android.graphics.Canvas;
+import android.annotation.TargetApi;
 import android.graphics.Rect;
-import android.graphics.drawable.Drawable;
-import android.support.v4.content.res.ResourcesCompat;
+import android.os.Build;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.RecyclerView.Adapter;
 import android.view.View;
 
+import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.ntp.cards.NewTabPageListItem;
 
 /**
  * A decorator that places separators between RecyclerView items of type
- * {@value NewTabPageListItem#VIEW_TYPE_SNIPPET}.
+ * {@value NewTabPageListItem#VIEW_TYPE_SNIPPET} and elevation.
  */
 public class SnippetItemDecoration extends RecyclerView.ItemDecoration {
-    private final Drawable mSeparator;
-
-    public SnippetItemDecoration(Context context) {
-        mSeparator = ResourcesCompat
-                .getDrawable(context.getResources(), R.drawable.snippet_separator, null);
-    }
+    public SnippetItemDecoration() {}
 
+    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
     @Override
-    public void getItemOffsets(Rect outRect, View view, RecyclerView parent,
-            RecyclerView.State state) {
-        if (!shouldPlaceSeparator(view, parent)) return;
-
-        // Add space below the item to show the separator.
-        outRect.set(0, 0, 0, mSeparator.getIntrinsicHeight());
-    }
-
-    @Override
-    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
-        final int left = parent.getPaddingLeft();
-        final int right = parent.getWidth() - parent.getPaddingRight();
-
-        // Draw the separators underneath the relevant items.
-        for (int i = 0; i < parent.getChildCount(); i++) {
-            View child = parent.getChildAt(i);
-            if (!shouldPlaceSeparator(child, parent)) continue;
-
-            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
-            final int top = child.getBottom() + params.bottomMargin;
-            final int bottom = top + mSeparator.getIntrinsicHeight();
-
-            mSeparator.setBounds(left, top, right, bottom);
-            mSeparator.draw(c);
-        }
-    }
-
-    /**
-     * Checks whether there should be a separator below the given view in the RecyclerView.
-     * Current logic checks if the current view and next view show snippets.
-     */
-    private boolean shouldPlaceSeparator(View view, RecyclerView parent) {
-        int childPos = parent.getChildAdapterPosition(view);
+    public void getItemOffsets(
+            Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
         Adapter<?> adapter = parent.getAdapter();
+        int childPos = parent.getChildAdapterPosition(view);
 
         // childPos can be NO_POSITION if the method is called with a view being removed from the
         // RecyclerView, for example when dismissing an item.
-        if (childPos == adapter.getItemCount() - 1 || childPos == RecyclerView.NO_POSITION) {
-            return false;
+        if (childPos == RecyclerView.NO_POSITION) {
+            return;
         }
 
-        return adapter.getItemViewType(childPos) == NewTabPageListItem.VIEW_TYPE_SNIPPET
-                && adapter.getItemViewType(childPos + 1) == NewTabPageListItem.VIEW_TYPE_SNIPPET;
+        // Only applies to view type snippet.
+        if (adapter.getItemViewType(childPos) != NewTabPageListItem.VIEW_TYPE_SNIPPET) return;
+
+        // Add elevation to each snippet if supported.
+        ApiCompatibilityUtils.setElevation(
+                view, parent.getContext().getResources().getDimensionPixelSize(
+                              R.dimen.snippets_card_elevation));
+
+        // Add space below the item. Checks if the current and next view are snippets.
+        if (adapter.getItemViewType(childPos + 1) == NewTabPageListItem.VIEW_TYPE_SNIPPET) {
+            outRect.set(0, 0, 0, parent.getContext().getResources().getDimensionPixelSize(
+                                         R.dimen.snippets_vertical_spacing));
+        }
     }
 }