Avoid unnecessary calls to updateTransformHint

It was observed that this could start to take
noticeable time with high layer counts, I guess
due to the acquisition of one mutex per layer per call. Anyway
it looks like there's no need to call it if a display transaction
didn't occur.

Test: Existing tests pass.
Change-Id: I1918d326a6d0ed32a0a5fea4008a746d328b335d

1 files changed, 13 insertions, 10 deletions

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 142892e874..03a9df762b 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2338,16 +2338,19 @@ void SurfaceFlinger::handleTransactionLocked(uint32_t transactionFlags)
                     }
                 }
             }
-            if (disp == NULL) {
-                // NOTE: TEMPORARY FIX ONLY. Real fix should cause layers to
-                // redraw after transform hint changes. See bug 8508397.
-
-                // could be null when this layer is using a layerStack
-                // that is not visible on any display. Also can occur at
-                // screen off/on times.
-                disp = getDefaultDisplayDeviceLocked();
+
+            if (transactionFlags & eDisplayTransactionNeeded) {
+                if (disp == NULL) {
+                    // NOTE: TEMPORARY FIX ONLY. Real fix should cause layers to
+                    // redraw after transform hint changes. See bug 8508397.
+
+                    // could be null when this layer is using a layerStack
+                    // that is not visible on any display. Also can occur at
+                    // screen off/on times.
+                    disp = getDefaultDisplayDeviceLocked();
+                }
+                layer->updateTransformHint(disp);
             }
-            layer->updateTransformHint(disp);
 
             first = false;
         });
@@ -4613,4 +4616,4 @@ void SurfaceFlinger::traverseLayersInDisplay(const sp<const DisplayDevice>& hw,
 
 #if defined(__gl2_h_)
 #error "don't include gl2/gl2.h in this file"
-#endif
\ No newline at end of file
+#endif