calculate wether we filter on a per-display basis

Change-Id: I79d80b432b20b3d02428da19add464ac1e2b9378

services/surfaceflinger/DisplayDevice.cpp

@@ -397,6 +397,10 @@ void DisplayDevice::updateGeometryTransform() {
         // Apply the logical translation, scale to physical size, apply the
         // physical translation and finally rotate to the physical orientation.
         mGlobalTransform = R * TP * S * TL;
+
+        const uint8_t type = mGlobalTransform.getType();
+        mNeedsFiltering = (!mGlobalTransform.preserveRects() ||
+                (type >= Transform::SCALE));
     }
 }
 

services/surfaceflinger/DisplayDevice.h

@@ -101,6 +101,7 @@ public:
     const Transform&        getTransform() const { return mGlobalTransform; }
     const Rect&             getViewport() const { return mViewport; }
     const Rect&             getFrame() const { return mFrame; }
+    bool                    needsFiltering() const { return mNeedsFiltering; }
 
     uint32_t                getLayerStack() const { return mLayerStack; }
     int32_t                 getDisplayType() const { return mType; }
@@ -195,6 +196,7 @@ private:
     Rect mViewport;
     Rect mFrame;
     Transform mGlobalTransform;
+    bool mNeedsFiltering;
 };
 
 }; // namespace android

services/surfaceflinger/Layer.cpp

@@ -344,7 +344,7 @@ void Layer::onDraw(const sp<const DisplayDevice>& hw, const Region& clip) const
 
     if (!isProtected()) {
         // TODO: we could be more subtle with isFixedSize()
-        const bool useFiltering = getFiltering() || needsFiltering() || isFixedSize();
+        const bool useFiltering = getFiltering() || needsFiltering(hw) || isFixedSize();
 
         // Query the texture matrix given our current filtering mode.
         float textureMatrix[16];

services/surfaceflinger/LayerBase.cpp

@@ -87,6 +87,10 @@ void LayerBase::initStates(uint32_t w, uint32_t h, uint32_t flags)
     mDrawingState = mCurrentState;
 }
 
+bool LayerBase::needsFiltering(const sp<const DisplayDevice>& hw) const {
+    return mNeedsFiltering || hw->needsFiltering();
+}
+
 void LayerBase::commitTransaction() {
     mDrawingState = mCurrentState;
 }

services/surfaceflinger/LayerBase.h

@@ -197,7 +197,7 @@ public:
     /**
      * needsLinearFiltering - true if this surface's state requires filtering
      */
-    virtual bool needsFiltering() const { return mNeedsFiltering; }
+    virtual bool needsFiltering(const sp<const DisplayDevice>& hw) const;
 
     /**
      * isSecure - true if this surface is secure, that is if it prevents