Update dim state when new window is drawn

We used to update the dim state only in prepareSurfaces, but this lead
to flickers with windows that were showing during a transition. Therefore,
when a new window is drawn, we recalculate the state of the possible
affected dim and update it in the same transaction.

Bug: 327332488
Test: DimmerTests
Flag: com.android.window.flags.update_dims_when_window_shown
Change-Id: Idc52a3ee6875218350e34ad44f1c28f6cb5666a1

4 files changed, 52 insertions, 6 deletions

diff --git a/core/java/android/window/flags/windowing_frontend.aconfig b/core/java/android/window/flags/windowing_frontend.aconfig
index a786fc24d9a7..03e230c39f05 100644
--- a/core/java/android/window/flags/windowing_frontend.aconfig
+++ b/core/java/android/window/flags/windowing_frontend.aconfig
@@ -181,6 +181,17 @@ flag {
 }
 
 flag {
+  name: "update_dims_when_window_shown"
+  namespace: "windowing_frontend"
+  description: "Check if we need to update dim layers when a new window draws the first frame"
+  bug: "327332488"
+  is_fixed_read_only: true
+  metadata {
+    purpose: PURPOSE_BUGFIX
+  }
+}
+
+flag {
     name: "release_snapshot_aggressively"
     namespace: "windowing_frontend"
     description: "Actively release task snapshot memory"
diff --git a/services/core/java/com/android/server/wm/DimmerAnimationHelper.java b/services/core/java/com/android/server/wm/DimmerAnimationHelper.java
index faf6dc667916..bc188959164d 100644
--- a/services/core/java/com/android/server/wm/DimmerAnimationHelper.java
+++ b/services/core/java/com/android/server/wm/DimmerAnimationHelper.java
@@ -109,7 +109,9 @@ public class DimmerAnimationHelper {
 
     // Sets the requested layer to reparent the dim to without applying it immediately
     void setRequestedGeometryParent(WindowContainer<?> geometryParent) {
-        mRequestedProperties.mGeometryParent = geometryParent;
+        if (geometryParent != null) {
+            mRequestedProperties.mGeometryParent = geometryParent;
+        }
     }
 
     // Sets a requested change without applying it immediately
@@ -139,9 +141,14 @@ public class DimmerAnimationHelper {
             dim.remove(t);
             return;
         }
+        if (!dim.mDimSurface.isValid()) {
+            Log.e(TAG, "Dimming surface " + dim.mDimSurface + " has already been released!"
+                    + " Can not apply changes.");
+            return;
+        }
 
         dim.ensureVisible(t);
-        reparent(dim.mDimSurface,
+        reparent(dim,
                 startProperties.mGeometryParent != mRequestedProperties.mGeometryParent
                         ? mRequestedProperties.mGeometryParent.getSurfaceControl() : null,
                 mRequestedProperties.mDimmingContainer != startProperties.mDimmingContainer
@@ -159,7 +166,7 @@ public class DimmerAnimationHelper {
                         "%s skipping animation and directly setting alpha=%f, blur=%d",
                         dim, startProperties.mAlpha,
                         mRequestedProperties.mBlurRadius);
-                setCurrentAlphaBlur(dim.mDimSurface, t);
+                setCurrentAlphaBlur(dim, t);
                 dim.mSkipAnimation = false;
             } else {
                 startAnimation(t, dim, startProperties, mRequestedProperties);
@@ -186,7 +193,7 @@ public class DimmerAnimationHelper {
                     synchronized (dim.mHostContainer.mWmService.mGlobalLock) {
                         SurfaceControl.Transaction finishTransaction =
                                 dim.mHostContainer.getSyncTransaction();
-                        setCurrentAlphaBlur(dim.mDimSurface, finishTransaction);
+                        setCurrentAlphaBlur(dim, finishTransaction);
                         if (targetAlpha == 0f && !dim.isDimming()) {
                             dim.remove(finishTransaction);
                         }
@@ -229,10 +236,11 @@ public class DimmerAnimationHelper {
     /**
      * Change the geometry and relative parent of this dim layer
      */
-    static void reparent(@NonNull SurfaceControl dimLayer,
+    void reparent(@NonNull Dimmer.DimState dim,
                   @Nullable SurfaceControl newGeometryParent,
                   @Nullable SurfaceControl newRelativeParent,
                   @NonNull SurfaceControl.Transaction t) {
+        final SurfaceControl dimLayer = dim.mDimSurface;
         try {
             if (newGeometryParent != null) {
                 t.reparent(dimLayer, newGeometryParent);
@@ -245,7 +253,8 @@ public class DimmerAnimationHelper {
         }
     }
 
-    void setCurrentAlphaBlur(@NonNull SurfaceControl sc, @NonNull SurfaceControl.Transaction t) {
+    void setCurrentAlphaBlur(@NonNull Dimmer.DimState dim, @NonNull SurfaceControl.Transaction t) {
+        final SurfaceControl sc = dim.mDimSurface;
         try {
             t.setAlpha(sc, mCurrentProperties.mAlpha);
             t.setBackgroundBlurRadius(sc, mCurrentProperties.mBlurRadius);
diff --git a/services/core/java/com/android/server/wm/WindowContainer.java b/services/core/java/com/android/server/wm/WindowContainer.java
index 1eeb3ecaf9d6..9d4652957487 100644
--- a/services/core/java/com/android/server/wm/WindowContainer.java
+++ b/services/core/java/com/android/server/wm/WindowContainer.java
@@ -2875,6 +2875,15 @@ class WindowContainer<E extends WindowContainer> extends ConfigurationContainer<
     }
 
     /**
+     * Go through the hierarchy to allow windows to request a dim if needed
+     */
+    void adjustDims() {
+        for (int i = 0; i < mChildren.size(); i++) {
+            mChildren.get(i).adjustDims();
+        }
+    }
+
+    /**
      * Trigger a call to prepareSurfaces from the animation thread, such that pending transactions
      * will be applied.
      */
diff --git a/services/core/java/com/android/server/wm/WindowState.java b/services/core/java/com/android/server/wm/WindowState.java
index 021be5727bf6..b5276303f6b9 100644
--- a/services/core/java/com/android/server/wm/WindowState.java
+++ b/services/core/java/com/android/server/wm/WindowState.java
@@ -4409,6 +4409,17 @@ class WindowState extends WindowContainer<WindowState> implements WindowManagerP
         for (int i = mChildren.size() - 1; i >= 0; i--) {
             committed |= mChildren.get(i).commitFinishDrawing(t);
         }
+
+        // When a new activity is showing, update dim in this transaction
+        if (Flags.updateDimsWhenWindowShown()) {
+            final Dimmer dimmer = getDimController();
+            final WindowContainer<?> dimParent = getDimParent();
+            if (dimmer != null && dimParent != null) {
+                dimParent.adjustDims();
+                dimmer.updateDims(t);
+            }
+        }
+
         // In case commitFinishDrawingLocked starts a window level animation, make sure the surface
         // operation (reparent to leash) is synced with the visibility by transition.
         if (getAnimationLeash() != null) {
@@ -5304,6 +5315,12 @@ class WindowState extends WindowContainer<WindowState> implements WindowManagerP
         super.prepareSurfaces();
     }
 
+    @Override
+    void adjustDims() {
+        applyDims();
+        super.adjustDims();
+    }
+
     void updateSurfacePositionIfNeeded() {
         if (mWindowFrames.mRelFrame.top == mWindowFrames.mLastRelFrame.top
                 && mWindowFrames.mRelFrame.left == mWindowFrames.mLastRelFrame.left) {