GestureNav: Limit exclusion rects

Add limits for system gesture exclusion on the left and right edges.
This prevents non-immersive-sticky apps from totally disabling the
back gesture.

Bug: 135522625
Test: atest SystemGestureExclusionRectsTest

Change-Id: Ib26161663a6aababe803d3c70044f4017bdbe675
Exempt-From-Owner-Approval: Already +2ed on another branch

6 files changed, 175 insertions, 8 deletions

diff --git a/api/test-current.txt b/api/test-current.txt
index bf2730abcb99..fe73fecb6b86 100644
--- a/api/test-current.txt
+++ b/api/test-current.txt
@@ -2301,6 +2301,7 @@ package android.provider {
     field public static final String NAMESPACE_PRIVACY = "privacy";
     field public static final String NAMESPACE_ROLLBACK = "rollback";
     field public static final String NAMESPACE_ROLLBACK_BOOT = "rollback_boot";
+    field public static final String NAMESPACE_WINDOW_MANAGER = "android:window_manager";
   }
 
   public static interface DeviceConfig.OnPropertiesChangedListener {
@@ -2317,6 +2318,10 @@ package android.provider {
     method @Nullable public String getString(@NonNull String, @Nullable String);
   }
 
+  public static interface DeviceConfig.WindowManager {
+    field public static final String KEY_SYSTEM_GESTURE_EXCLUSION_LIMIT_DP = "system_gesture_exclusion_limit_dp";
+  }
+
   public final class MediaStore {
     method @RequiresPermission(android.Manifest.permission.CLEAR_APP_USER_DATA) public static void deleteContributedMedia(android.content.Context, String, android.os.UserHandle) throws java.io.IOException;
     method @RequiresPermission(android.Manifest.permission.CLEAR_APP_USER_DATA) public static long getContributedMediaSize(android.content.Context, String, android.os.UserHandle) throws java.io.IOException;
diff --git a/core/java/android/provider/DeviceConfig.java b/core/java/android/provider/DeviceConfig.java
index 01b6758f8b15..48faf114d2d7 100644
--- a/core/java/android/provider/DeviceConfig.java
+++ b/core/java/android/provider/DeviceConfig.java
@@ -293,6 +293,15 @@ public final class DeviceConfig {
     public static final String NAMESPACE_SETTINGS_UI = "settings_ui";
 
     /**
+     * Namespace for window manager related features. The names to access the properties in this
+     * namespace should be defined in {@link WindowManager}.
+     *
+     * @hide
+     */
+    @TestApi
+    public static final String NAMESPACE_WINDOW_MANAGER = "android:window_manager";
+
+    /**
      * List of namespaces which can be read without READ_DEVICE_CONFIG permission
      *
      * @hide
@@ -309,6 +318,23 @@ public final class DeviceConfig {
     @TestApi
     public static final String NAMESPACE_PRIVACY = "privacy";
 
+    /**
+     * Interface for accessing keys belonging to {@link #NAMESPACE_WINDOW_MANAGER}.
+     * @hide
+     */
+    @TestApi
+    public interface WindowManager {
+
+        /**
+         * Key for accessing the system gesture exclusion limit (an integer in dp).
+         *
+         * @see android.provider.DeviceConfig#NAMESPACE_WINDOW_MANAGER
+         * @hide
+         */
+        @TestApi
+        String KEY_SYSTEM_GESTURE_EXCLUSION_LIMIT_DP = "system_gesture_exclusion_limit_dp";
+    }
+
     private static final Object sLock = new Object();
     @GuardedBy("sLock")
     private static ArrayMap<OnPropertiesChangedListener, Pair<String, Executor>> sListeners =
diff --git a/services/core/java/com/android/server/wm/DisplayContent.java b/services/core/java/com/android/server/wm/DisplayContent.java
index 57ed92d8b794..72a7fcfe1e29 100644
--- a/services/core/java/com/android/server/wm/DisplayContent.java
+++ b/services/core/java/com/android/server/wm/DisplayContent.java
@@ -30,16 +30,21 @@ import static android.content.pm.ActivityInfo.SCREEN_ORIENTATION_USER;
 import static android.content.res.Configuration.ORIENTATION_LANDSCAPE;
 import static android.content.res.Configuration.ORIENTATION_PORTRAIT;
 import static android.os.Trace.TRACE_TAG_WINDOW_MANAGER;
+import static android.util.DisplayMetrics.DENSITY_DEFAULT;
 import static android.view.Display.DEFAULT_DISPLAY;
 import static android.view.Display.FLAG_PRIVATE;
 import static android.view.Display.FLAG_SHOULD_SHOW_SYSTEM_DECORATIONS;
 import static android.view.Display.INVALID_DISPLAY;
 import static android.view.InsetsState.TYPE_IME;
+import static android.view.InsetsState.TYPE_LEFT_GESTURES;
+import static android.view.InsetsState.TYPE_RIGHT_GESTURES;
 import static android.view.Surface.ROTATION_0;
 import static android.view.Surface.ROTATION_180;
 import static android.view.Surface.ROTATION_270;
 import static android.view.Surface.ROTATION_90;
 import static android.view.View.GONE;
+import static android.view.View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
+import static android.view.View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY;
 import static android.view.WindowManager.DOCKED_BOTTOM;
 import static android.view.WindowManager.DOCKED_INVALID;
 import static android.view.WindowManager.DOCKED_TOP;
@@ -135,6 +140,7 @@ import static com.android.server.wm.WindowManagerService.logSurface;
 import static com.android.server.wm.WindowState.RESIZE_HANDLE_WIDTH_IN_DP;
 import static com.android.server.wm.WindowStateAnimator.DRAW_PENDING;
 import static com.android.server.wm.WindowStateAnimator.READY_TO_SHOW;
+import static com.android.server.wm.utils.RegionUtils.forEachRect;
 import static com.android.server.wm.utils.RegionUtils.rectListToRegion;
 
 import android.animation.AnimationHandler;
@@ -323,6 +329,7 @@ class DisplayContent extends WindowContainer<DisplayContent.DisplayChildWindowCo
     private final RemoteCallbackList<ISystemGestureExclusionListener>
             mSystemGestureExclusionListeners = new RemoteCallbackList<>();
     private final Region mSystemGestureExclusion = new Region();
+    private int mSystemGestureExclusionLimit;
 
     /**
      * For default display it contains real metrics, empty for others.
@@ -893,6 +900,8 @@ class DisplayContent extends WindowContainer<DisplayContent.DisplayChildWindowCo
         mWallpaperController = new WallpaperController(mWmService, this);
         display.getDisplayInfo(mDisplayInfo);
         display.getMetrics(mDisplayMetrics);
+        mSystemGestureExclusionLimit = mWmService.mSystemGestureExclusionLimitDp
+                * mDisplayMetrics.densityDpi / DENSITY_DEFAULT;
         isDefaultDisplay = mDisplayId == DEFAULT_DISPLAY;
         mDisplayFrames = new DisplayFrames(mDisplayId, mDisplayInfo,
                 calculateDisplayCutoutForRotation(mDisplayInfo.rotation));
@@ -1548,8 +1557,8 @@ class DisplayContent extends WindowContainer<DisplayContent.DisplayChildWindowCo
             longSize = height;
         }
 
-        final int shortSizeDp = shortSize * DisplayMetrics.DENSITY_DEFAULT / mBaseDisplayDensity;
-        final int longSizeDp = longSize * DisplayMetrics.DENSITY_DEFAULT / mBaseDisplayDensity;
+        final int shortSizeDp = shortSize * DENSITY_DEFAULT / mBaseDisplayDensity;
+        final int longSizeDp = longSize * DENSITY_DEFAULT / mBaseDisplayDensity;
 
         mDisplayPolicy.updateConfigurationAndScreenSizeDependentBehaviors();
         mDisplayRotation.configure(width, height, shortSizeDp, longSizeDp);
@@ -2199,6 +2208,18 @@ class DisplayContent extends WindowContainer<DisplayContent.DisplayChildWindowCo
         onDisplayChanged(this);
     }
 
+    @Override
+    void onDisplayChanged(DisplayContent dc) {
+        super.onDisplayChanged(dc);
+        updateSystemGestureExclusionLimit();
+    }
+
+    void updateSystemGestureExclusionLimit() {
+        mSystemGestureExclusionLimit = mWmService.mSystemGestureExclusionLimitDp
+                * mDisplayMetrics.densityDpi / DENSITY_DEFAULT;
+        updateSystemGestureExclusion();
+    }
+
     void initializeDisplayBaseInfo() {
         final DisplayManagerInternal displayManagerInternal = mWmService.mDisplayManagerInternal;
         if (displayManagerInternal != null) {
@@ -5130,24 +5151,35 @@ class DisplayContent extends WindowContainer<DisplayContent.DisplayChildWindowCo
 
     @VisibleForTesting
     Region calculateSystemGestureExclusion() {
+        final Region unhandled = Region.obtain();
+        unhandled.set(0, 0, mDisplayFrames.mDisplayWidth, mDisplayFrames.mDisplayHeight);
+
+        final Rect leftEdge = mInsetsStateController.getSourceProvider(TYPE_LEFT_GESTURES)
+                .getSource().getFrame();
+        final Rect rightEdge = mInsetsStateController.getSourceProvider(TYPE_RIGHT_GESTURES)
+                .getSource().getFrame();
+
         final Region global = Region.obtain();
         final Region touchableRegion = Region.obtain();
         final Region local = Region.obtain();
+        final int[] remainingLeftRight =
+                {mSystemGestureExclusionLimit, mSystemGestureExclusionLimit};
 
         // Traverse all windows bottom up to assemble the gesture exclusion rects.
         // For each window, we only take the rects that fall within its touchable region.
         forAllWindows(w -> {
             if (w.cantReceiveTouchInput() || !w.isVisible()
-                    || (w.getAttrs().flags & FLAG_NOT_TOUCHABLE) != 0) {
+                    || (w.getAttrs().flags & FLAG_NOT_TOUCHABLE) != 0
+                    || unhandled.isEmpty()) {
                 return;
             }
             final boolean modal =
                     (w.mAttrs.flags & (FLAG_NOT_TOUCH_MODAL | FLAG_NOT_FOCUSABLE)) == 0;
 
-            // Only keep the exclusion zones from the windows behind where the current window
-            // isn't touchable.
+            // Get the touchable region of the window, and intersect with where the screen is still
+            // touchable, i.e. touchable regions on top are not covering it yet.
             w.getTouchableRegion(touchableRegion);
-            global.op(touchableRegion, Op.DIFFERENCE);
+            touchableRegion.op(unhandled, Op.INTERSECT);
 
             rectListToRegion(w.getSystemGestureExclusion(), local);
 
@@ -5159,13 +5191,78 @@ class DisplayContent extends WindowContainer<DisplayContent.DisplayChildWindowCo
             // A window can only exclude system gestures where it is actually touchable
             local.op(touchableRegion, Op.INTERSECT);
 
-            global.op(local, Op.UNION);
-        }, false /* topToBottom */);
+            // Apply restriction if necessary.
+            if (needsGestureExclusionRestrictions(w, mLastDispatchedSystemUiVisibility)) {
+
+                // Processes the region along the left edge.
+                remainingLeftRight[0] = addToGlobalAndConsumeLimit(local, global, leftEdge,
+                        remainingLeftRight[0]);
+
+                // Processes the region along the right edge.
+                remainingLeftRight[1] = addToGlobalAndConsumeLimit(local, global, rightEdge,
+                        remainingLeftRight[1]);
+
+                // Adds the middle (unrestricted area)
+                final Region middle = Region.obtain(local);
+                middle.op(leftEdge, Op.DIFFERENCE);
+                middle.op(rightEdge, Op.DIFFERENCE);
+                global.op(middle, Op.UNION);
+                middle.recycle();
+            } else {
+                global.op(local, Op.UNION);
+            }
+            unhandled.op(touchableRegion, Op.DIFFERENCE);
+        }, true /* topToBottom */);
         local.recycle();
         touchableRegion.recycle();
+        unhandled.recycle();
         return global;
     }
 
+    /**
+     * @return Whether gesture exclusion area should be restricted from the window depending on the
+     *         current SystemUI visibility flags.
+     */
+    private static boolean needsGestureExclusionRestrictions(WindowState win, int sysUiVisibility) {
+        final int type = win.mAttrs.type;
+        final int stickyHideNavFlags =
+                SYSTEM_UI_FLAG_HIDE_NAVIGATION | SYSTEM_UI_FLAG_IMMERSIVE_STICKY;
+        final boolean stickyHideNav =
+                (sysUiVisibility & stickyHideNavFlags) == stickyHideNavFlags;
+        return !stickyHideNav && type != TYPE_INPUT_METHOD && type != TYPE_STATUS_BAR
+                && win.getActivityType() != ACTIVITY_TYPE_HOME;
+    }
+
+    /**
+     * Adds a local gesture exclusion area to the global area while applying a limit per edge.
+     *
+     * @param local The gesture exclusion area to add.
+     * @param global The destination.
+     * @param edge Only processes the part in that region.
+     * @param limit How much limit in pixels we have.
+     * @return How much of the limit are remaining.
+     */
+    private static int addToGlobalAndConsumeLimit(Region local, Region global, Rect edge,
+            int limit) {
+        final Region r = Region.obtain(local);
+        r.op(edge, Op.INTERSECT);
+
+        final int[] remaining = {limit};
+        forEachRect(r, rect -> {
+            if (remaining[0] <= 0) {
+                return;
+            }
+            final int height = rect.height();
+            if (height > remaining[0]) {
+                rect.bottom = rect.top + remaining[0];
+            }
+            remaining[0] -= height;
+            global.op(rect, Op.UNION);
+        });
+        r.recycle();
+        return remaining[0];
+    }
+
     void registerSystemGestureExclusionListener(ISystemGestureExclusionListener listener) {
         mSystemGestureExclusionListeners.register(listener);
         final boolean changed;
diff --git a/services/core/java/com/android/server/wm/WindowManagerService.java b/services/core/java/com/android/server/wm/WindowManagerService.java
index 6750ece1861e..54f712cc6cef 100644
--- a/services/core/java/com/android/server/wm/WindowManagerService.java
+++ b/services/core/java/com/android/server/wm/WindowManagerService.java
@@ -32,6 +32,7 @@ import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.os.Process.SYSTEM_UID;
 import static android.os.Process.myPid;
 import static android.os.Trace.TRACE_TAG_WINDOW_MANAGER;
+import static android.provider.DeviceConfig.WindowManager.KEY_SYSTEM_GESTURE_EXCLUSION_LIMIT_DP;
 import static android.provider.Settings.Global.DEVELOPMENT_FORCE_DESKTOP_MODE_ON_EXTERNAL_DISPLAYS;
 import static android.view.Display.DEFAULT_DISPLAY;
 import static android.view.Display.INVALID_DISPLAY;
@@ -155,6 +156,7 @@ import android.os.Build;
 import android.os.Bundle;
 import android.os.Debug;
 import android.os.Handler;
+import android.os.HandlerExecutor;
 import android.os.IBinder;
 import android.os.IRemoteCallback;
 import android.os.Looper;
@@ -176,6 +178,7 @@ import android.os.SystemService;
 import android.os.Trace;
 import android.os.UserHandle;
 import android.os.WorkSource;
+import android.provider.DeviceConfig;
 import android.provider.Settings;
 import android.service.vr.IVrManager;
 import android.service.vr.IVrStateCallbacks;
@@ -382,6 +385,8 @@ public class WindowManagerService extends IWindowManager.Stub
 
     private static final int ANIMATION_COMPLETED_TIMEOUT_MS = 5000;
 
+    private static final int MIN_GESTURE_EXCLUSION_LIMIT_DP = 200;
+
     final WindowTracing mWindowTracing;
 
     final private KeyguardDisableHandler mKeyguardDisableHandler;
@@ -840,6 +845,8 @@ public class WindowManagerService extends IWindowManager.Stub
     final ArrayList<WindowChangeListener> mWindowChangeListeners = new ArrayList<>();
     boolean mWindowsChanged = false;
 
+    int mSystemGestureExclusionLimitDp;
+
     public interface WindowChangeListener {
         public void windowsChanged();
         public void focusChanged();
@@ -1134,6 +1141,21 @@ public class WindowManagerService extends IWindowManager.Stub
                 this, mInputManager, mActivityTaskManager, mH.getLooper());
         mDragDropController = new DragDropController(this, mH.getLooper());
 
+        mSystemGestureExclusionLimitDp = Math.max(MIN_GESTURE_EXCLUSION_LIMIT_DP,
+                DeviceConfig.getInt(DeviceConfig.NAMESPACE_WINDOW_MANAGER,
+                        KEY_SYSTEM_GESTURE_EXCLUSION_LIMIT_DP, 0));
+        DeviceConfig.addOnPropertiesChangedListener(DeviceConfig.NAMESPACE_WINDOW_MANAGER,
+                new HandlerExecutor(mH), properties -> {
+                    synchronized (mGlobalLock) {
+                        final int exclusionLimitDp = Math.max(MIN_GESTURE_EXCLUSION_LIMIT_DP,
+                                properties.getInt(KEY_SYSTEM_GESTURE_EXCLUSION_LIMIT_DP, 0));
+                        if (mSystemGestureExclusionLimitDp != exclusionLimitDp) {
+                            mSystemGestureExclusionLimitDp = exclusionLimitDp;
+                            mRoot.forAllDisplays(DisplayContent::updateSystemGestureExclusionLimit);
+                        }
+                    }
+                });
+
         LocalServices.addService(WindowManagerInternal.class, new LocalService());
     }
 
diff --git a/services/core/java/com/android/server/wm/utils/RegionUtils.java b/services/core/java/com/android/server/wm/utils/RegionUtils.java
index 1458440f7b81..8cd6f8826083 100644
--- a/services/core/java/com/android/server/wm/utils/RegionUtils.java
+++ b/services/core/java/com/android/server/wm/utils/RegionUtils.java
@@ -18,8 +18,10 @@ package com.android.server.wm.utils;
 
 import android.graphics.Rect;
 import android.graphics.Region;
+import android.graphics.RegionIterator;
 
 import java.util.List;
+import java.util.function.Consumer;
 
 /**
  * Utility methods to handle Regions.
@@ -42,4 +44,18 @@ public class RegionUtils {
             outRegion.union(rects.get(i));
         }
     }
+
+    /**
+     * Applies actions on each rect contained within a {@code Region}.
+     *
+     * @param region the given region.
+     * @param rectConsumer the action holder.
+     */
+    public static void forEachRect(Region region, Consumer<Rect> rectConsumer) {
+        final RegionIterator it = new RegionIterator(region);
+        final Rect rect = new Rect();
+        while (it.next(rect)) {
+            rectConsumer.accept(rect);
+        }
+    }
 }
diff --git a/services/tests/wmtests/AndroidManifest.xml b/services/tests/wmtests/AndroidManifest.xml
index 4c27a3ce0bf3..8c4544249b5c 100644
--- a/services/tests/wmtests/AndroidManifest.xml
+++ b/services/tests/wmtests/AndroidManifest.xml
@@ -36,6 +36,7 @@
     <uses-permission android:name="android.permission.READ_FRAME_BUFFER" />
     <uses-permission android:name="android.permission.WAKE_LOCK" />
     <uses-permission android:name="android.permission.REORDER_TASKS" />
+    <uses-permission android:name="android.permission.READ_DEVICE_CONFIG" />
 
     <!-- TODO: Remove largeHeap hack when memory leak is fixed (b/123984854) -->
     <application android:debuggable="true"