make transform hint multi-display aware

if a layer is not mirrored, we now use its display
as the source for the transfrom hint calculation
instead of always using the default (main) display.

this change does two thing:
1) we make updateTransformHint take a DisplayDevice
   as a parameter instead of hard-coding the
   main display.

2) each time we do a transaction that could change
   the hint, we go through all layers and
   figure out which display should be used for their
   transform hint.

Bug: 7599344
Change-Id: I9b04a95e6c372dd770bacf81d8ef6f8e31b87b83

1 files changed, 5 insertions, 7 deletions

diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 064f689..7edbdc5 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -110,7 +110,8 @@ void Layer::onFirstRef()
     mSurfaceTexture->setDefaultMaxBufferCount(3);
 #endif
 
-    updateTransformHint();
+    const sp<const DisplayDevice> hw(mFlinger->getDefaultDisplayDevice());
+    updateTransformHint(hw);
 }
 
 Layer::~Layer()
@@ -767,15 +768,12 @@ uint32_t Layer::getEffectiveUsage(uint32_t usage) const
     return usage;
 }
 
-void Layer::updateTransformHint() const {
+void Layer::updateTransformHint(const sp<const DisplayDevice>& hw) const {
     uint32_t orientation = 0;
     if (!mFlinger->mDebugDisableTransformHint) {
-        // The transform hint is used to improve performance on the main
-        // display -- we can only have a single transform hint, it cannot
+        // The transform hint is used to improve performance, but we can
+        // only have a single transform hint, it cannot
         // apply to all displays.
-        // This is why we use the default display here. This is not an
-        // oversight.
-        sp<const DisplayDevice> hw(mFlinger->getDefaultDisplayDevice());
         const Transform& planeTransform(hw->getTransform());
         orientation = planeTransform.getOrientation();
         if (orientation & Transform::ROT_INVALID) {