From c66633b385d20b44bdd632b1c736dd512f4ea1c6 Mon Sep 17 00:00:00 2001
From: hunterstich <hunterstich@google.com>
Date: Wed, 26 Jan 2022 13:09:58 -0800
Subject: [PATCH] [NavigationRail] Added support for opting in/out of the
 NavigationRail automatically adding system top and bottom window insets.

PiperOrigin-RevId: 424424554
---
 .../layout/cat_navigation_rail_animated.xml   |  3 +-
 .../layout/cat_navigation_rail_fragment.xml   |  7 +++--
 .../navigationrail/NavigationRailView.java    | 31 +++++++++++++++++--
 .../navigationrail/res/values/attrs.xml       |  6 ++++
 .../navigationrail/res/values/styles.xml      |  1 +
 5 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/catalog/java/io/material/catalog/navigationrail/res/layout/cat_navigation_rail_animated.xml b/catalog/java/io/material/catalog/navigationrail/res/layout/cat_navigation_rail_animated.xml
index 344a4dd9405..43dcdc26d69 100644
--- a/catalog/java/io/material/catalog/navigationrail/res/layout/cat_navigation_rail_animated.xml
+++ b/catalog/java/io/material/catalog/navigationrail/res/layout/cat_navigation_rail_animated.xml
@@ -20,5 +20,6 @@
     android:id="@+id/cat_navigation_rail"
     android:layout_width="wrap_content"
     android:layout_height="match_parent"
-    app:menu="@menu/navigation_rail_animated_menu"/>
+    app:menu="@menu/navigation_rail_animated_menu"
+    android:fitsSystemWindows="false"/>
 
diff --git a/catalog/java/io/material/catalog/navigationrail/res/layout/cat_navigation_rail_fragment.xml b/catalog/java/io/material/catalog/navigationrail/res/layout/cat_navigation_rail_fragment.xml
index 570aa584e6e..7a5889f2daa 100644
--- a/catalog/java/io/material/catalog/navigationrail/res/layout/cat_navigation_rail_fragment.xml
+++ b/catalog/java/io/material/catalog/navigationrail/res/layout/cat_navigation_rail_fragment.xml
@@ -16,8 +16,8 @@
   -->
 <LinearLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
-  xmlns:app="http://schemas.android.com/apk/res-auto"
-  android:id="@+id/content"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:id="@+id/content"
     android:baselineAligned="false"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
@@ -26,7 +26,8 @@
     android:id="@+id/cat_navigation_rail"
     android:layout_width="wrap_content"
     android:layout_height="match_parent"
-    app:menu="@menu/navigation_rail_menu"/>
+    app:menu="@menu/navigation_rail_menu"
+    android:fitsSystemWindows="false"/>
 
   <ScrollView
       android:layout_width="0dp"
diff --git a/lib/java/com/google/android/material/navigationrail/NavigationRailView.java b/lib/java/com/google/android/material/navigationrail/NavigationRailView.java
index 2f6758767ee..903a38495bc 100644
--- a/lib/java/com/google/android/material/navigationrail/NavigationRailView.java
+++ b/lib/java/com/google/android/material/navigationrail/NavigationRailView.java
@@ -103,6 +103,8 @@ public class NavigationRailView extends NavigationBarView {
 
   private final int topMargin;
   @Nullable private View headerView;
+  @Nullable private Boolean paddingTopSystemWindowInsets = null;
+  @Nullable private Boolean paddingBottomSystemWindowInsets = null;
 
   public NavigationRailView(@NonNull Context context) {
     this(context, null);
@@ -146,6 +148,17 @@ public NavigationRailView(
               R.styleable.NavigationRailView_itemMinHeight, NO_ITEM_MINIMUM_HEIGHT));
     }
 
+    if (attributes.hasValue(R.styleable.NavigationRailView_paddingTopSystemWindowInsets)) {
+      paddingTopSystemWindowInsets =
+          attributes.getBoolean(
+              R.styleable.NavigationRailView_paddingTopSystemWindowInsets, false);
+    }
+    if (attributes.hasValue(R.styleable.NavigationRailView_paddingBottomSystemWindowInsets)) {
+      paddingBottomSystemWindowInsets =
+          attributes.getBoolean(
+              R.styleable.NavigationRailView_paddingBottomSystemWindowInsets, false);
+    }
+
     attributes.recycle();
 
     applyWindowInsets();
@@ -163,8 +176,12 @@ public WindowInsetsCompat onApplyWindowInsets(
               @NonNull RelativePadding initialPadding) {
             // Apply the top, bottom, and start padding for a start edge aligned
             // NavigationRailView to dodge the system status and navigation bars
-            initialPadding.top += insets.getSystemWindowInsetTop();
-            initialPadding.bottom += insets.getSystemWindowInsetBottom();
+            if (shouldApplyWindowInsetPadding(paddingTopSystemWindowInsets)) {
+              initialPadding.top += insets.getInsets(WindowInsetsCompat.Type.systemBars()).top;
+            }
+            if (shouldApplyWindowInsetPadding(paddingBottomSystemWindowInsets)) {
+              initialPadding.top += insets.getInsets(WindowInsetsCompat.Type.systemBars()).bottom;
+            }
 
             boolean isRtl = ViewCompat.getLayoutDirection(view) == ViewCompat.LAYOUT_DIRECTION_RTL;
             int systemWindowInsetLeft = insets.getSystemWindowInsetLeft();
@@ -176,6 +193,16 @@ public WindowInsetsCompat onApplyWindowInsets(
         });
   }
 
+  /**
+   * Whether the top or bottom of this view should be padded in to avoid the system window insets.
+   *
+   * If the {@code paddingInsetFlag} is set, that value will take precedent. Otherwise,
+   * fitsSystemWindow will be used.
+   */
+  private boolean shouldApplyWindowInsetPadding(Boolean paddingInsetFlag) {
+    return paddingInsetFlag != null ? paddingInsetFlag : ViewCompat.getFitsSystemWindows(this);
+  }
+
   @Override
   protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     int minWidthSpec = makeMinWidthSpec(widthMeasureSpec);
diff --git a/lib/java/com/google/android/material/navigationrail/res/values/attrs.xml b/lib/java/com/google/android/material/navigationrail/res/values/attrs.xml
index 2dce868c446..3d4c3deb16e 100644
--- a/lib/java/com/google/android/material/navigationrail/res/values/attrs.xml
+++ b/lib/java/com/google/android/material/navigationrail/res/values/attrs.xml
@@ -36,6 +36,12 @@
       <!-- Gravity.BOTTOM | Gravity.CENTER_HORIZONTAL -->
       <enum name="bottom" value="81"/>
     </attr>
+    <!-- Whether the navigation rail should apply padding to have its menu
+         items and optional header below the top window insets. -->
+    <attr name="paddingTopSystemWindowInsets"/>
+    <!-- Whether the navigation rail should apply padding to have its menu
+         items above the bottom window insets. -->
+    <attr name="paddingBottomSystemWindowInsets"/>
   </declare-styleable>
 
 </resources>
diff --git a/lib/java/com/google/android/material/navigationrail/res/values/styles.xml b/lib/java/com/google/android/material/navigationrail/res/values/styles.xml
index c7e699381f0..7554908a961 100644
--- a/lib/java/com/google/android/material/navigationrail/res/values/styles.xml
+++ b/lib/java/com/google/android/material/navigationrail/res/values/styles.xml
@@ -38,6 +38,7 @@
     <item name="itemTextColor">@color/mtrl_navigation_bar_item_tint</item>
     <item name="labelVisibilityMode">auto</item>
     <item name="menuGravity">top</item>
+    <item name="android:fitsSystemWindows">true</item>
   </style>
 
   <style name="Widget.MaterialComponents.NavigationRailView.Compact">