[3171580] Fix two typos related to fixed-size buffers

mFixedSize was never set, this bug was introduced during some "cleanup", in
practice this could cause some issues when a fixed-size buffer was used and
the window was resized.

Layer::drawForSreenShot() had a typo that had no effect.

mFixedSize was used to determine if filtering was needed, which was a bit too
conservative and created a dependency between filtering and "fixed size" states
which should exist.

Now we enable filtering based on the size of the buffer vs. the size of the layer.

Change-Id: I32044e91b0c944c1b137efdceb3f01dfaa78119d

4 files changed, 19 insertions, 21 deletions

diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 5018fb3..81cb15d 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -57,7 +57,7 @@ Layer::Layer(SurfaceFlinger* flinger,
         mSecure(false),
         mTextureManager(),
         mBufferManager(mTextureManager),
-        mWidth(0), mHeight(0), mFixedSize(false)
+        mWidth(0), mHeight(0), mNeedsScaling(false), mFixedSize(false)
 {
 }
 
@@ -216,13 +216,10 @@ slowpath:
 
 void Layer::drawForSreenShot() const
 {
-    bool currentFixedSize = mFixedSize;
-    bool currentBlending = mNeedsBlending;
-    const_cast<Layer*>(this)->mFixedSize = false;
-    const_cast<Layer*>(this)->mFixedSize = true;
+    const bool currentFiltering = mNeedsFiltering;
+    const_cast<Layer*>(this)->mNeedsFiltering = true;
     LayerBase::drawForSreenShot();
-    const_cast<Layer*>(this)->mFixedSize = currentFixedSize;
-    const_cast<Layer*>(this)->mNeedsBlending = currentBlending;
+    const_cast<Layer*>(this)->mNeedsFiltering = currentFiltering;
 }
 
 void Layer::onDraw(const Region& clip) const
@@ -260,11 +257,10 @@ void Layer::onDraw(const Region& clip) const
 bool Layer::needsFiltering() const
 {
     if (!(mFlags & DisplayHardware::SLOW_CONFIG)) {
-        // NOTE: there is a race here, because mFixedSize is updated in a
-        // binder transaction. however, it doesn't really matter since it is
-        // evaluated each time we draw. To be perfectly correct, this flag
-        // would have to be associated with a buffer.
-        if (mFixedSize)
+        // if our buffer is not the same size than ourselves,
+        // we need filtering.
+        Mutex::Autolock _l(mLock);
+        if (mNeedsScaling)
             return true;
     }
     return LayerBase::needsFiltering();
@@ -321,6 +317,7 @@ sp<GraphicBuffer> Layer::requestBuffer(int index,
         Mutex::Autolock _l(mLock);
 
         // zero means default
+        mFixedSize = reqWidth && reqHeight;
         if (!reqFormat) reqFormat = mFormat;
         if (!reqWidth)  reqWidth = mWidth;
         if (!reqHeight) reqHeight = mHeight;
@@ -334,6 +331,7 @@ sp<GraphicBuffer> Layer::requestBuffer(int index,
             mReqWidth  = reqWidth;
             mReqHeight = reqHeight;
             mReqFormat = reqFormat;
+            mNeedsScaling = mWidth != mReqWidth || mHeight != mReqHeight;
 
             lcblk->reallocateAllExcept(index);
         }
@@ -457,6 +455,7 @@ void Layer::setBufferSize(uint32_t w, uint32_t h) {
     Mutex::Autolock _l(mLock);
     mWidth = w;
     mHeight = h;
+    mNeedsScaling = mWidth != mReqWidth || mHeight != mReqHeight;
 }
 
 bool Layer::isFixedSize() const {
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 263c372..a93fcb1 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -230,6 +230,7 @@ private:
     uint32_t mReqWidth;
     uint32_t mReqHeight;
     uint32_t mReqFormat;
+    bool mNeedsScaling;
     bool mFixedSize;
 };
 
diff --git a/services/surfaceflinger/LayerBase.cpp b/services/surfaceflinger/LayerBase.cpp
index 64eed4b..79c6d0d 100644
--- a/services/surfaceflinger/LayerBase.cpp
+++ b/services/surfaceflinger/LayerBase.cpp
@@ -216,14 +216,10 @@ uint32_t LayerBase::doTransaction(uint32_t flags)
         flags |= eVisibleRegion;
         this->contentDirty = true;
 
-        mNeedsFiltering = false;
-        if (!(mFlags & DisplayHardware::SLOW_CONFIG)) {
-            // we may use linear filtering, if the matrix scales us
-            const uint8_t type = temp.transform.getType();
-            if (!temp.transform.preserveRects() || (type >= Transform::SCALE)) {
-                mNeedsFiltering = true;
-            }
-        }
+        // we may use linear filtering, if the matrix scales us
+        const uint8_t type = temp.transform.getType();
+        mNeedsFiltering = (!temp.transform.preserveRects() ||
+                (type >= Transform::SCALE));
     }
 
     // Commit the transaction
diff --git a/services/surfaceflinger/LayerBase.h b/services/surfaceflinger/LayerBase.h
index d688f65..633df96 100644
--- a/services/surfaceflinger/LayerBase.h
+++ b/services/surfaceflinger/LayerBase.h
@@ -185,7 +185,9 @@ public:
     /**
      * needsLinearFiltering - true if this surface needs filtering
      */
-    virtual bool needsFiltering() const { return mNeedsFiltering; }
+    virtual bool needsFiltering() const {
+        return (!(mFlags & DisplayHardware::SLOW_CONFIG)) && mNeedsFiltering;
+    }
 
     /**
      * isSecure - true if this surface is secure, that is if it prevents