Detect layout change of paramsForRotation precisely

WindowManager.LayoutParams doesn't override equals(). It returns
false if the instances are different. So after writing/reading
from parcel, even if the fields are identical, the comparison
of Arrays.equals(paramsForRotation, o.paramsForRotation) always
returns false.

This is the first step as a signal to decide whether the screen
configuration needs to be recomputed according to if there is a
layout change from decor windows.

Bug: 238399969
Test: atest FrameworksCoreTests:android.view.WindowParamsTest

Change-Id: I82582ff48064bbf009403d2c0980a69157860f90

core/java/android/view/WindowManager.java

@@ -4396,15 +4396,42 @@ public interface WindowManager extends ViewManager {
                 changes |= LAYOUT_CHANGED;
             }
 
-            if (!Arrays.equals(paramsForRotation, o.paramsForRotation)) {
+            if (paramsForRotation != o.paramsForRotation) {
+                if ((changes & LAYOUT_CHANGED) == 0) {
+                    if (paramsForRotation != null && o.paramsForRotation != null
+                            && paramsForRotation.length == o.paramsForRotation.length) {
+                        for (int i = paramsForRotation.length - 1; i >= 0; i--) {
+                            if (hasLayoutDiff(paramsForRotation[i], o.paramsForRotation[i])) {
+                                changes |= LAYOUT_CHANGED;
+                                break;
+                            }
+                        }
+                    } else {
+                        changes |= LAYOUT_CHANGED;
+                    }
+                }
                 paramsForRotation = o.paramsForRotation;
                 checkNonRecursiveParams();
-                changes |= LAYOUT_CHANGED;
             }
 
             return changes;
         }
 
+        /**
+         * Returns {@code true} if the 2 params may have difference results of
+         * {@link WindowLayout#computeFrames}.
+         */
+        private static boolean hasLayoutDiff(LayoutParams a, LayoutParams b) {
+            return a.width != b.width || a.height != b.height || a.x != b.x || a.y != b.y
+                    || a.horizontalMargin != b.horizontalMargin
+                    || a.verticalMargin != b.verticalMargin
+                    || a.layoutInDisplayCutoutMode != b.layoutInDisplayCutoutMode
+                    || a.gravity != b.gravity || !Arrays.equals(a.providedInsets, b.providedInsets)
+                    || a.mFitInsetsTypes != b.mFitInsetsTypes
+                    || a.mFitInsetsSides != b.mFitInsetsSides
+                    || a.mFitInsetsIgnoringVisibility != b.mFitInsetsIgnoringVisibility;
+        }
+
         @Override
         public String debug(String output) {
             output += "Contents of " + this + ":";

core/tests/coretests/src/android/view/WindowParamsTest.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2022 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 android.view;
+
+import static org.junit.Assert.assertEquals;
+
+import android.os.Parcel;
+import android.platform.test.annotations.Presubmit;
+
+import androidx.test.filters.SmallTest;
+
+import org.junit.Test;
+
+@Presubmit
+@SmallTest
+public class WindowParamsTest {
+
+    @Test
+    public void testParamsForRotation() {
+        final WindowManager.LayoutParams paramsA = new WindowManager.LayoutParams();
+        initParamsForRotation(paramsA);
+        final Parcel parcel = Parcel.obtain();
+        paramsA.writeToParcel(parcel, 0);
+        parcel.setDataPosition(0);
+
+        final WindowManager.LayoutParams paramsB = new WindowManager.LayoutParams(parcel);
+        assertEquals(0, paramsA.copyFrom(paramsB));
+
+        for (int i = 1; i <= 12; i++) {
+            initParamsForRotation(paramsA);
+            changeField(i, paramsA.paramsForRotation[0]);
+            assertEquals("Change not found for case " + i,
+                    WindowManager.LayoutParams.LAYOUT_CHANGED, paramsA.copyFrom(paramsB));
+        }
+
+        parcel.recycle();
+    }
+
+    private static void initParamsForRotation(WindowManager.LayoutParams params) {
+        params.paramsForRotation = new WindowManager.LayoutParams[4];
+        for (int i = 0; i < 4; i++) {
+            params.paramsForRotation[i] = new WindowManager.LayoutParams();
+        }
+    }
+
+    private static void changeField(int fieldCase, WindowManager.LayoutParams params) {
+        switch (fieldCase) {
+            case 1:
+                params.width++;
+                break;
+            case 2:
+                params.height++;
+                break;
+            case 3:
+                params.x++;
+                break;
+            case 4:
+                params.y++;
+                break;
+            case 5:
+                params.horizontalMargin++;
+                break;
+            case 6:
+                params.verticalMargin++;
+                break;
+            case 7:
+                params.layoutInDisplayCutoutMode++;
+                break;
+            case 8:
+                params.gravity++;
+                break;
+            case 9:
+                params.providedInsets = new InsetsFrameProvider[0];
+                break;
+            case 10:
+                params.setFitInsetsTypes(0);
+                break;
+            case 11:
+                params.setFitInsetsSides(0);
+                break;
+            case 12:
+                params.setFitInsetsIgnoringVisibility(!params.isFitInsetsIgnoringVisibility());
+                break;
+        }
+    }
+}