Don't take app screenshot in minimize docked stack.

When the docked stack is minimized its app windows are cropped
significantly so any screenshot taken will not display the apps
contain. So, we avoid taking a screenshot in that case.

This situation is going to be improve some in O when we switch
recents to also use saved surfaces in which cases it will be able
to display the last app content the user saw vs. just the app's
background color.

Bug: 29830173
Change-Id: I003aa074126ddcb57d5ff6dda756293146646196

diff --git a/services/core/java/com/android/server/am/ActivityStack.java b/services/core/java/com/android/server/am/ActivityStack.java
index 60d3d1e..1b552b5 100644 (file)
--- a/services/core/java/com/android/server/am/ActivityStack.java
+++ b/services/core/java/com/android/server/am/ActivityStack.java
@@ -29,6 +29,7 @@ import static android.content.pm.ActivityInfo.CONFIG_SMALLEST_SCREEN_SIZE;
 import static android.content.pm.ActivityInfo.FLAG_RESUME_WHILE_PAUSING;
 import static android.content.pm.ActivityInfo.FLAG_SHOW_FOR_ALL_USERS;
 import static android.content.res.Configuration.SCREENLAYOUT_UNDEFINED;
+import static android.view.Display.DEFAULT_DISPLAY;
 import static com.android.server.am.ActivityManagerDebugConfig.DEBUG_ADD_REMOVE;
 import static com.android.server.am.ActivityManagerDebugConfig.DEBUG_ALL;
 import static com.android.server.am.ActivityManagerDebugConfig.DEBUG_APP;
@@ -68,6 +69,7 @@ import static com.android.server.am.ActivityManagerDebugConfig.POSTFIX_VISIBILIT
 import static com.android.server.am.ActivityManagerDebugConfig.TAG_AM;
 import static com.android.server.am.ActivityManagerDebugConfig.TAG_WITH_CLASS_NAME;
 import static com.android.server.am.ActivityManagerService.LOCK_SCREEN_SHOWN;
+import static com.android.server.am.ActivityManagerService.TAKE_FULLSCREEN_SCREENSHOTS;
 import static com.android.server.am.ActivityRecord.APPLICATION_ACTIVITY_TYPE;
 import static com.android.server.am.ActivityRecord.HOME_ACTIVITY_TYPE;
 import static com.android.server.am.ActivityRecord.STARTING_WINDOW_REMOVED;
@@ -669,7 +671,7 @@ final class ActivityStack {
 
     final boolean isOnHomeDisplay() {
         return isAttached() &&
-                mActivityContainer.mActivityDisplay.mDisplayId == Display.DEFAULT_DISPLAY;
+                mActivityContainer.mActivityDisplay.mDisplayId == DEFAULT_DISPLAY;
     }
 
     void moveToFront(String reason) {
@@ -1041,22 +1043,32 @@ final class ActivityStack {
 
         int w = mService.mThumbnailWidth;
         int h = mService.mThumbnailHeight;
+
+        if (w <= 0) {
+            Slog.e(TAG, "\tInvalid thumbnail dimensions: " + w + "x" + h);
+            return null;
+        }
+
+        if (mStackId == DOCKED_STACK_ID && mStackSupervisor.mIsDockMinimized) {
+            // When the docked stack is minimized its app windows are cropped significantly so any
+            // screenshot taken will not display the apps contain. So, we avoid taking a screenshot
+            // in that case.
+            if (DEBUG_SCREENSHOTS) Slog.e(TAG, "\tIn minimized docked stack");
+            return null;
+        }
+
         float scale = 1f;
-        if (w > 0) {
-            if (DEBUG_SCREENSHOTS) Slog.d(TAG_SCREENSHOTS, "\tTaking screenshot");
+        if (DEBUG_SCREENSHOTS) Slog.d(TAG_SCREENSHOTS, "\tTaking screenshot");
 
-            // When this flag is set, we currently take the fullscreen screenshot of the activity
-            // but scaled to half the size.  This gives us a "good-enough" fullscreen thumbnail to
-            // use within SystemUI while keeping memory usage low.
-            if (ActivityManagerService.TAKE_FULLSCREEN_SCREENSHOTS) {
-                w = h = -1;
-                scale = mService.mFullscreenThumbnailScale;
-            }
-            return mWindowManager.screenshotApplications(who.appToken, Display.DEFAULT_DISPLAY,
-                    w, h, scale);
+        // When this flag is set, we currently take the fullscreen screenshot of the activity but
+        // scaled to half the size. This gives us a "good-enough" fullscreen thumbnail to use within
+        // SystemUI while keeping memory usage low.
+        if (TAKE_FULLSCREEN_SCREENSHOTS) {
+            w = h = -1;
+            scale = mService.mFullscreenThumbnailScale;
         }
-        Slog.e(TAG, "Invalid thumbnail dimensions: " + w + "x" + h);
-        return null;
+
+        return mWindowManager.screenshotApplications(who.appToken, DEFAULT_DISPLAY, w, h, scale);
     }
 
     /**