Don't allow focus on activity in minimized split-screen.

Return false for ActivityRecord.isFocusable() for activities in minimized
split-screen since their windows can't be focused or interacted with.
Also, move focus off split-screen primary stack when we enter minimize
mode.

Change-Id: Iecec5d55123f1c3530c461314fa69498575ef5c3
Fixes: 74404706
Fixes: 74837107
Fixes: 74919175
Test: Put an app in split-screen, launch it from launch again, and observe ANR.
Test: atest ActivityManagerAppConfigurationTests#testDialogWhenLargeSplitSmall
Test: atest ActivityManagerSplitScreenTests#testNoUserLeaveHintOnMultiWindowModeChanged

3 files changed, 21 insertions, 9 deletions

diff --git a/services/core/java/com/android/server/am/ActivityRecord.java b/services/core/java/com/android/server/am/ActivityRecord.java
index 8c49472b58c6..68c47d58f92d 100644
--- a/services/core/java/com/android/server/am/ActivityRecord.java
+++ b/services/core/java/com/android/server/am/ActivityRecord.java
@@ -1193,6 +1193,9 @@ final class ActivityRecord extends ConfigurationContainer implements AppWindowCo
     }
 
     boolean isFocusable() {
+        if (inSplitScreenPrimaryWindowingMode() && mStackSupervisor.mIsDockMinimized) {
+            return false;
+        }
         return getWindowConfiguration().canReceiveKeys() || isAlwaysFocusable();
     }
 
diff --git a/services/core/java/com/android/server/am/ActivityStack.java b/services/core/java/com/android/server/am/ActivityStack.java
index 2c4eac0e391b..1223632ccf53 100644
--- a/services/core/java/com/android/server/am/ActivityStack.java
+++ b/services/core/java/com/android/server/am/ActivityStack.java
@@ -3416,7 +3416,7 @@ class ActivityStack<T extends StackWindowController> extends ConfigurationContai
     }
 
     /** Find next proper focusable stack and make it focused. */
-    private boolean adjustFocusToNextFocusableStack(String reason) {
+    boolean adjustFocusToNextFocusableStack(String reason) {
         return adjustFocusToNextFocusableStack(reason, false /* allowFocusSelf */);
     }
 
diff --git a/services/core/java/com/android/server/am/ActivityStackSupervisor.java b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
index efc0d7d87e63..be826f7dc025 100644
--- a/services/core/java/com/android/server/am/ActivityStackSupervisor.java
+++ b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
@@ -2455,19 +2455,20 @@ public class ActivityStackSupervisor extends ConfigurationContainer implements D
 
                 if (currentWindowingMode == WINDOWING_MODE_SPLIT_SCREEN_SECONDARY
                         && candidate == null && stack.inSplitScreenPrimaryWindowingMode()) {
-                    // If the currently focused stack is in split-screen secondary we would prefer
-                    // the focus to move to another split-screen secondary stack or fullscreen stack
-                    // over the primary split screen stack to avoid:
-                    // - Moving the focus to the primary split-screen stack when it can't be focused
-                    //   because it will be minimized, but AM doesn't know that yet
-                    // - primary split-screen stack overlapping with a fullscreen stack when a
-                    //   fullscreen stack is higher in z than the next split-screen stack. Assistant
-                    //   stack, I am looking at you...
+                    // If the currently focused stack is in split-screen secondary we save off the
+                    // top primary split-screen stack as a candidate for focus because we might
+                    // prefer focus to move to an other stack to avoid primary split-screen stack
+                    // overlapping with a fullscreen stack when a fullscreen stack is higher in z
+                    // than the next split-screen stack. Assistant stack, I am looking at you...
                     // We only move the focus to the primary-split screen stack if there isn't a
                     // better alternative.
                     candidate = stack;
                     continue;
                 }
+                if (candidate != null && stack.inSplitScreenSecondaryWindowingMode()) {
+                    // Use the candidate stack since we are now at the secondary split-screen.
+                    return candidate;
+                }
                 return stack;
             }
         }
@@ -4413,6 +4414,14 @@ public class ActivityStackSupervisor extends ConfigurationContainer implements D
 
     void setDockedStackMinimized(boolean minimized) {
         mIsDockMinimized = minimized;
+        if (mIsDockMinimized) {
+            final ActivityStack current = getFocusedStack();
+            if (current.inSplitScreenPrimaryWindowingMode()) {
+                // The primary split-screen stack can't be focused while it is minimize, so move
+                // focus to something else.
+                current.adjustFocusToNextFocusableStack("setDockedStackMinimized");
+            }
+        }
     }
 
     void wakeUp(String reason) {