SurfaceFlinger and libgui: Support for child layers.

Add support for parenting Layers in a tree. Layers
follow scene-graph style rules, that is to say:
   1. A child is cropped to the final bounds of the parent.
   2. A child inherits the parent's transform (including position)
   3. A child's Z ordering is relative to the parent and bounded between
      the parents siblings.
   4. A childs lifetime is bounded by it's parents lifetime.

Test: New tests in Transaction_test plus manual testing with later branches.
Change-Id: I96f8ad863665b9a70b6f845561344c297b7e6eff
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 3959341..bf224ae 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -42,6 +42,7 @@
 
 #include "FrameTracker.h"
 #include "Client.h"
+#include "LayerVector.h"
 #include "MonitoredProducer.h"
 #include "SurfaceFlinger.h"
 #include "SurfaceFlingerConsumer.h"
@@ -168,6 +169,7 @@
     bool setFinalCrop(const Rect& crop);
     bool setLayerStack(uint32_t layerStack);
     bool setDataSpace(android_dataspace dataSpace);
+    uint32_t getLayerStack() const;
     void deferTransactionUntil(const sp<IBinder>& handle, uint64_t frameNumber);
     bool setOverrideScalingMode(int32_t overrideScalingMode);
 
@@ -219,6 +221,14 @@
     virtual bool isVisible() const;
 
     /*
+     * isHiddenByPolicy - true if this layer has been forced invisible.
+     * just because this is false, doesn't mean isVisible() is true.
+     * For example if this layer has no active buffer, it may not be hidden by
+     * policy, but it still can not be visible.
+     */
+    virtual bool isHiddenByPolicy() const;
+
+    /*
      * isFixedSize - true if content has a fixed size
      */
     virtual bool isFixedSize() const;
@@ -422,6 +432,26 @@
 
     bool getTransformToDisplayInverse() const;
 
+    Transform getTransform() const;
+
+    void traverseInReverseZOrder(const std::function<void(Layer*)>& exec);
+    void traverseInZOrder(const std::function<void(Layer*)>& exec);
+
+    void addChild(const sp<Layer>& layer);
+    // Returns index if removed, or negative value otherwise
+    // for symmetry with Vector::remove
+    ssize_t removeChild(const sp<Layer>& layer);
+    sp<Layer> getParent() const { return mParent.promote(); }
+    bool hasParent() const { return getParent() != nullptr; }
+
+    Rect computeScreenBounds(bool reduceTransparentRegion = true) const;
+    bool setChildLayer(const sp<Layer>& childLayer, int32_t z);
+
+    // Copy the current list of children to the drawing state. Called by
+    // SurfaceFlinger to complete a transaction.
+    void commitChildList();
+
+    int32_t getZ() const;
 protected:
     // constant
     sp<SurfaceFlinger> mFlinger;
@@ -462,7 +492,12 @@
     bool needsFiltering(const sp<const DisplayDevice>& hw) const;
 
     uint32_t getEffectiveUsage(uint32_t usage) const;
+
     gfx::FloatRect computeCrop(const sp<const DisplayDevice>& hw) const;
+    // Compute the initial crop as specified by parent layers and the SurfaceControl
+    // for this layer. Does not include buffer crop from the IGraphicBufferProducer
+    // client, as that should not affect child clipping. Returns in screen space.
+    Rect computeInitialCrop(const sp<const DisplayDevice>& hw) const;
     bool isCropped() const;
     static bool getOpacityForFormat(uint32_t format);
 
@@ -478,6 +513,8 @@
     // Loads the corresponding system property once per process
     static bool latchUnsignaledBuffers();
 
+    void setParent(const sp<Layer>& layer);
+
     // -----------------------------------------------------------------------
 
     class SyncPoint
@@ -532,6 +569,8 @@
     void popPendingState(State* stateToCommit);
     bool applyPendingStates(State* stateToCommit);
 
+    void clearSyncPoints();
+
     // Returns mCurrentScaling mode (originating from the
     // Client) or mOverrideScalingMode mode (originating from
     // the Surface Controller) if set.
@@ -662,6 +701,13 @@
 
     bool mAutoRefresh;
     bool mFreezePositionUpdates;
+
+    // Child list about to be committed/used for editing.
+    LayerVector mCurrentChildren;
+    // Child list used for rendering.
+    LayerVector mDrawingChildren;
+
+    wp<Layer> mParent;
 };
 
 // ---------------------------------------------------------------------------