Dont update thumbnails of freeform windows on focus change

Windows should not update their thumbnails upon a focus change since
it costs a lot of time to capture the content and the thumbnail would
be outdated short time later anyways since the window is still
visible anyways.

Bug: 23562904
Change-Id: If5d23a1058e83030770905827d682f649a579f7a

2 files changed, 16 insertions, 1 deletions

diff --git a/services/core/java/com/android/server/am/ActivityStack.java b/services/core/java/com/android/server/am/ActivityStack.java
index 965f5b626508..f50df3a1f34f 100644
--- a/services/core/java/com/android/server/am/ActivityStack.java
+++ b/services/core/java/com/android/server/am/ActivityStack.java
@@ -902,7 +902,14 @@ final class ActivityStack {
         prev.task.touchActiveTime();
         clearLaunchTime(prev);
         final ActivityRecord next = mStackSupervisor.topRunningActivityLocked();
-        if (mService.mHasRecents && (next == null || next.noDisplay || next.task != prev.task || uiSleeping)) {
+        // In freeform mode we only update the thumbnail when there is no thumbnail yet since every
+        // focus change will request a thumbnail to be taken.
+        // Note furthermore that since windows can change their content in freeform mode all the
+        // time a thumbnail is possibly constantly outdated.
+        if (mService.mHasRecents &&
+                (next == null || next.noDisplay || next.task != prev.task || uiSleeping) &&
+                (!prev.task.hasThumbnail() ||
+                        prev.task.stack.mStackId != FREEFORM_WORKSPACE_STACK_ID)) {
             prev.updateThumbnailLocked(screenshotActivities(prev), null);
         }
         stopFullyDrawnTraceIfNeeded();
diff --git a/services/core/java/com/android/server/am/TaskRecord.java b/services/core/java/com/android/server/am/TaskRecord.java
index 712b8cc9af6b..9cbaec53ce60 100644
--- a/services/core/java/com/android/server/am/TaskRecord.java
+++ b/services/core/java/com/android/server/am/TaskRecord.java
@@ -478,6 +478,14 @@ final class TaskRecord {
     }
 
     /**
+     * Returns true when we have a thumbnail.
+     * @return Returns true if there is a thumbnail.
+     */
+    boolean hasThumbnail() {
+        return mLastThumbnail != null;
+    }
+
+    /**
      * Sets the last thumbnail.
      * @return whether the thumbnail was set
      */