Set the back button sysUiVisibility as well

Changes to window sysUiVisibility is not picked up after the window
is laid out, so add a call to set the decor view's sysUiVisibility as
well.

Test: ./gradlew connectedAndroidTest
Bug: 72840994
Change-Id: I6f0744599f46adf1840738f226b4394e5b7ed1df

3 files changed, 32 insertions, 7 deletions

diff --git a/library/main/src/com/android/setupwizardlib/util/SystemBarHelper.java b/library/main/src/com/android/setupwizardlib/util/SystemBarHelper.java
index 1c5f3d3..b31e82e 100644
--- a/library/main/src/com/android/setupwizardlib/util/SystemBarHelper.java
+++ b/library/main/src/com/android/setupwizardlib/util/SystemBarHelper.java
@@ -24,6 +24,7 @@ import android.content.res.TypedArray;
 import android.os.Build.VERSION;
 import android.os.Build.VERSION_CODES;
 import android.os.Handler;
+import android.support.annotation.RequiresPermission;
 import android.util.Log;
 import android.view.View;
 import android.view.ViewGroup;
@@ -183,12 +184,25 @@ public class SystemBarHelper {
         }
     }
 
+    /**
+     * Sets whether the back button on the software navigation bar is visible. This only works if
+     * you have the STATUS_BAR permission. Otherwise framework will filter out this flag and this
+     * method call will not have any effect.
+     *
+     * <p>IMPORTANT: Do not assume that users have no way to go back when the back button is hidden.
+     * Many devices have physical back buttons, and accessibility services like TalkBack may have
+     * gestures mapped to back. Please use onBackPressed, onKeyDown, or other similar ways to
+     * make sure back button events are still handled (or ignored) properly.
+     */
+    @RequiresPermission("android.permission.STATUS_BAR")
     public static void setBackButtonVisible(final Window window, final boolean visible) {
         if (VERSION.SDK_INT >= VERSION_CODES.HONEYCOMB) {
             if (visible) {
                 removeVisibilityFlag(window, STATUS_BAR_DISABLE_BACK);
+                removeImmersiveFlagsFromDecorView(window, STATUS_BAR_DISABLE_BACK);
             } else {
                 addVisibilityFlag(window, STATUS_BAR_DISABLE_BACK);
+                addImmersiveFlagsToDecorView(window, STATUS_BAR_DISABLE_BACK);
             }
         }
     }
@@ -217,7 +231,7 @@ public class SystemBarHelper {
      * {@link View#SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN} only takes effect when it is added to a view
      * instead of the window.
      */
-    @TargetApi(VERSION_CODES.LOLLIPOP)
+    @TargetApi(VERSION_CODES.HONEYCOMB)
     private static void addImmersiveFlagsToDecorView(final Window window, final int vis) {
         getDecorView(window, new OnDecorViewInstalledListener() {
             @Override
@@ -227,7 +241,7 @@ public class SystemBarHelper {
         });
     }
 
-    @TargetApi(VERSION_CODES.LOLLIPOP)
+    @TargetApi(VERSION_CODES.HONEYCOMB)
     private static void removeImmersiveFlagsFromDecorView(final Window window, final int vis) {
         getDecorView(window, new OnDecorViewInstalledListener() {
             @Override
diff --git a/library/self.gradle b/library/self.gradle
index 86dea0e..a4bff4e 100644
--- a/library/self.gradle
+++ b/library/self.gradle
@@ -29,6 +29,7 @@ android.sourceSets {
             androidTestImplementation 'com.android.support.test:runner:1.0.0'
             androidTestImplementation 'com.google.dexmaker:dexmaker:1.2'
             androidTestImplementation 'com.google.dexmaker:dexmaker-mockito:1.2'
+            androidTestImplementation 'com.google.truth:truth:0.31'
             androidTestImplementation 'junit:junit:4.+'
             androidTestImplementation 'org.mockito:mockito-core:1.9.5'
         }
diff --git a/library/test/instrumentation/src/com/android/setupwizardlib/test/SystemBarHelperTest.java b/library/test/instrumentation/src/com/android/setupwizardlib/test/SystemBarHelperTest.java
index d3142f1..98c28f6 100644
--- a/library/test/instrumentation/src/com/android/setupwizardlib/test/SystemBarHelperTest.java
+++ b/library/test/instrumentation/src/com/android/setupwizardlib/test/SystemBarHelperTest.java
@@ -16,6 +16,8 @@
 
 package com.android.setupwizardlib.test;
 
+import static com.google.common.truth.Truth.assertThat;
+
 import static org.junit.Assert.assertEquals;
 
 import android.annotation.SuppressLint;
@@ -194,11 +196,15 @@ public class SystemBarHelperTest {
     @UiThreadTest
     @Test
     public void testSetBackButtonVisibleTrue() {
-        final Window window = createWindowWithSystemUiVisibility(0x456);
+        final Window window = createWindowWithSystemUiVisibility(STATUS_BAR_DISABLE_BACK | 0x456);
         SystemBarHelper.setBackButtonVisible(window, true);
         if (VERSION.SDK_INT >= VERSION_CODES.HONEYCOMB) {
-            assertEquals("View visibility should be 0x456", 0x456,
-                    window.getAttributes().systemUiVisibility);
+            assertThat(window.getAttributes().systemUiVisibility)
+                    .named("window sysUiVisibility")
+                    .isEqualTo(0x456);
+            assertThat(window.getDecorView().getSystemUiVisibility())
+                    .named("decor view sysUiVisibility")
+                    .isEqualTo(0x456);
         }
     }
 
@@ -208,8 +214,12 @@ public class SystemBarHelperTest {
         final Window window = createWindowWithSystemUiVisibility(0x456);
         SystemBarHelper.setBackButtonVisible(window, false);
         if (VERSION.SDK_INT >= VERSION_CODES.HONEYCOMB) {
-            assertEquals("STATUS_BAR_DISABLE_BACK should be added to systemUiVisibility",
-                    0x456 | STATUS_BAR_DISABLE_BACK, window.getAttributes().systemUiVisibility);
+            assertThat(window.getAttributes().systemUiVisibility)
+                    .named("window sysUiVisibility")
+                    .isEqualTo(0x456 | STATUS_BAR_DISABLE_BACK);
+            assertThat(window.getDecorView().getSystemUiVisibility())
+                    .named("decor view sysUiVisibility")
+                    .isEqualTo(0x456 | STATUS_BAR_DISABLE_BACK);
         }
     }