Merge "Transform displayMetrics if needed" into udc-dev
diff --git a/libs/WindowManager/Jetpack/src/androidx/window/extensions/area/WindowAreaComponentImpl.java b/libs/WindowManager/Jetpack/src/androidx/window/extensions/area/WindowAreaComponentImpl.java
index 96190c4b..f9aa1bd 100644
--- a/libs/WindowManager/Jetpack/src/androidx/window/extensions/area/WindowAreaComponentImpl.java
+++ b/libs/WindowManager/Jetpack/src/androidx/window/extensions/area/WindowAreaComponentImpl.java
@@ -28,6 +28,7 @@
 import android.util.Pair;
 import android.view.Display;
 import android.view.DisplayAddress;
+import android.view.Surface;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -36,6 +37,7 @@
 
 import com.android.internal.R;
 import com.android.internal.annotations.GuardedBy;
+import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.ArrayUtils;
 
 import java.util.Objects;
@@ -229,27 +231,41 @@
      * @since {@link WindowExtensions#VENDOR_API_LEVEL_3}
      */
     @Override
+    @NonNull
     public DisplayMetrics getRearDisplayMetrics() {
-        DisplayMetrics metrics = null;
+        DisplayMetrics rearDisplayMetrics = null;
 
         // DISPLAY_CATEGORY_REAR displays are only available when you are in the concurrent
         // display state, so we have to look through all displays to match the address
-        Display[] displays = mDisplayManager.getDisplays(
+        final Display[] displays = mDisplayManager.getDisplays(
                 DisplayManager.DISPLAY_CATEGORY_ALL_INCLUDING_DISABLED);
+        final Display defaultDisplay = mDisplayManager.getDisplay(Display.DEFAULT_DISPLAY);
+
         for (int i = 0; i < displays.length; i++) {
             DisplayAddress.Physical address =
                     (DisplayAddress.Physical) displays[i].getAddress();
             if (mRearDisplayAddress == address.getPhysicalDisplayId()) {
-                metrics = new DisplayMetrics();
-                displays[i].getRealMetrics(metrics);
+                rearDisplayMetrics = new DisplayMetrics();
+                final Display rearDisplay = displays[i];
+
+                // We must always retrieve the metrics for the rear display regardless of if it is
+                // the default display or not.
+                rearDisplay.getRealMetrics(rearDisplayMetrics);
+
+                // TODO(b/287170025): This should be something like if (!rearDisplay.isEnabled)
+                //  instead. Currently when the rear display is disabled, its state is STATE_OFF.
+                if (rearDisplay.getDisplayId() != Display.DEFAULT_DISPLAY) {
+                    rotateRearDisplayMetricsIfNeeded(defaultDisplay.getRotation(),
+                            rearDisplay.getRotation(), rearDisplayMetrics);
+                }
                 break;
             }
         }
 
         synchronized (mLock) {
             // Update the rear display metrics with our latest value if one was received
-            if (metrics != null) {
-                mRearDisplayMetrics = metrics;
+            if (rearDisplayMetrics != null) {
+                mRearDisplayMetrics = rearDisplayMetrics;
             }
 
             return Objects.requireNonNullElseGet(mRearDisplayMetrics, DisplayMetrics::new);
@@ -540,6 +556,34 @@
         return mLastReportedRearDisplayPresentationStatus;
     }
 
+    @VisibleForTesting
+    static void rotateRearDisplayMetricsIfNeeded(
+            @Surface.Rotation int defaultDisplayRotation,
+            @Surface.Rotation int rearDisplayRotation,
+            @NonNull DisplayMetrics inOutMetrics) {
+        // If the rear display has a non-zero rotation, it means the backing DisplayContent /
+        // DisplayRotation is fresh.
+        if (rearDisplayRotation != Surface.ROTATION_0) {
+            return;
+        }
+
+        // If the default display is 0 or 180, the rear display must also be 0 or 180.
+        if (defaultDisplayRotation == Surface.ROTATION_0
+                || defaultDisplayRotation == Surface.ROTATION_180) {
+            return;
+        }
+
+        final int heightPixels = inOutMetrics.heightPixels;
+        final int widthPixels = inOutMetrics.widthPixels;
+        inOutMetrics.widthPixels = heightPixels;
+        inOutMetrics.heightPixels = widthPixels;
+
+        final int noncompatHeightPixels = inOutMetrics.noncompatHeightPixels;
+        final int noncompatWidthPixels = inOutMetrics.noncompatWidthPixels;
+        inOutMetrics.noncompatWidthPixels = noncompatHeightPixels;
+        inOutMetrics.noncompatHeightPixels = noncompatWidthPixels;
+    }
+
     /**
      * Callback for the {@link DeviceStateRequest} to be notified of when the request has been
      * activated or cancelled. This callback provides information to the client library
diff --git a/libs/WindowManager/Jetpack/tests/unittest/src/androidx/window/extensions/area/WindowAreaComponentImplTests.java b/libs/WindowManager/Jetpack/tests/unittest/src/androidx/window/extensions/area/WindowAreaComponentImplTests.java
new file mode 100644
index 0000000..ccb4ebe
--- /dev/null
+++ b/libs/WindowManager/Jetpack/tests/unittest/src/androidx/window/extensions/area/WindowAreaComponentImplTests.java
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package androidx.window.extensions.area;
+
+import static org.junit.Assert.assertEquals;
+
+import android.platform.test.annotations.Presubmit;
+import android.util.DisplayMetrics;
+import android.view.Surface;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import androidx.test.filters.SmallTest;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@Presubmit
+@SmallTest
+@RunWith(AndroidJUnit4.class)
+public class WindowAreaComponentImplTests {
+
+    private final DisplayMetrics mTestDisplayMetrics = new DisplayMetrics();
+
+    @Before
+    public void setup() {
+        mTestDisplayMetrics.widthPixels = 1;
+        mTestDisplayMetrics.heightPixels = 2;
+        mTestDisplayMetrics.noncompatWidthPixels = 3;
+        mTestDisplayMetrics.noncompatHeightPixels = 4;
+    }
+
+    /**
+     * Cases where the rear display metrics does not need to be transformed.
+     */
+    @Test
+    public void testRotateRearDisplayMetrics_noTransformNeeded() {
+        final DisplayMetrics originalMetrics = new DisplayMetrics();
+        originalMetrics.setTo(mTestDisplayMetrics);
+
+        WindowAreaComponentImpl.rotateRearDisplayMetricsIfNeeded(
+                Surface.ROTATION_0, Surface.ROTATION_0, mTestDisplayMetrics);
+        assertEquals(originalMetrics, mTestDisplayMetrics);
+
+        WindowAreaComponentImpl.rotateRearDisplayMetricsIfNeeded(
+                Surface.ROTATION_180, Surface.ROTATION_180, mTestDisplayMetrics);
+        assertEquals(originalMetrics, mTestDisplayMetrics);
+
+        WindowAreaComponentImpl.rotateRearDisplayMetricsIfNeeded(
+                Surface.ROTATION_0, Surface.ROTATION_180, mTestDisplayMetrics);
+        assertEquals(originalMetrics, mTestDisplayMetrics);
+
+        WindowAreaComponentImpl.rotateRearDisplayMetricsIfNeeded(
+                Surface.ROTATION_180, Surface.ROTATION_0, mTestDisplayMetrics);
+        assertEquals(originalMetrics, mTestDisplayMetrics);
+    }
+
+    /**
+     * Cases where the rear display metrics need to be transformed.
+     */
+    @Test
+    public void testRotateRearDisplayMetrics_transformNeeded() {
+        DisplayMetrics originalMetrics = new DisplayMetrics();
+        originalMetrics.setTo(mTestDisplayMetrics);
+
+        DisplayMetrics expectedMetrics = new DisplayMetrics();
+        expectedMetrics.setTo(mTestDisplayMetrics);
+        expectedMetrics.widthPixels = mTestDisplayMetrics.heightPixels;
+        expectedMetrics.heightPixels = mTestDisplayMetrics.widthPixels;
+        expectedMetrics.noncompatWidthPixels = mTestDisplayMetrics.noncompatHeightPixels;
+        expectedMetrics.noncompatHeightPixels = mTestDisplayMetrics.noncompatWidthPixels;
+
+        WindowAreaComponentImpl.rotateRearDisplayMetricsIfNeeded(
+                Surface.ROTATION_90, Surface.ROTATION_0, mTestDisplayMetrics);
+        assertEquals(expectedMetrics, mTestDisplayMetrics);
+
+        mTestDisplayMetrics.setTo(originalMetrics);
+        WindowAreaComponentImpl.rotateRearDisplayMetricsIfNeeded(
+                Surface.ROTATION_270, Surface.ROTATION_0, mTestDisplayMetrics);
+        assertEquals(expectedMetrics, mTestDisplayMetrics);
+    }
+}