Use path intersection instead of saveLayer+mesh to mask projected ripples

bug:14297149

SaveLayer's performance cost is high, and proportional to the surface
being projected onto. Since ripples (even unbounded ones) are now
always projected to the arbitrary background content behind them, this
cost is especially important to avoid.

This removes the last semi-secret, saveLayer from the projected
ripple implementation.

Also fixes the HW test app to correctly demonstrate this projection
masking behavior.

Additionaly, alters PathTessellator to gracefully handle
counter-clockwise paths, and simplifies the work done by
ShadowTessellator to ensure all of its paths are counterclockwise.

Change-Id: Ibe9e12812bd10a774e20b1d444a140c368cbba8c

1 files changed, 27 insertions, 0 deletions

diff --git a/libs/hwui/Snapshot.h b/libs/hwui/Snapshot.h
index 4d704abe205a..af6ad727da85 100644
--- a/libs/hwui/Snapshot.h
+++ b/libs/hwui/Snapshot.h
@@ -63,6 +63,17 @@ public:
     float radius;
 };
 
+class ProjectionPathMask {
+public:
+    /** static void* operator new(size_t size); PURPOSELY OMITTED, allocator only **/
+    static void* operator new(size_t size, LinearAllocator& allocator) {
+        return allocator.alloc(size);
+    }
+
+    const SkPath* projectionMask;
+    Matrix4 projectionMaskTransform;
+};
+
 /**
  * A snapshot holds information about the current state of the rendering
  * surface. A snapshot is usually created whenever the user calls save()
@@ -190,6 +201,11 @@ public:
             float radius, bool highPriority);
 
     /**
+     * Sets (and replaces) the current projection mask
+     */
+    void setProjectionPathMask(LinearAllocator& allocator, const SkPath* path);
+
+    /**
      * Indicates whether this snapshot should be ignored. A snapshot
      * is typically ignored if its layer is invisible or empty.
      */
@@ -201,6 +217,12 @@ public:
     bool hasPerspectiveTransform() const;
 
     /**
+     * Fills outTransform with the current, total transform to screen space,
+     * across layer boundaries.
+     */
+    void buildScreenSpaceTransform(Matrix4* outTransform) const;
+
+    /**
      * Dirty flags.
      */
     int flags;
@@ -272,6 +294,11 @@ public:
      */
     const RoundRectClipState* roundRectClipState;
 
+    /**
+     * Current projection masking path - used exclusively to mask tessellated circles.
+     */
+    const ProjectionPathMask* projectionPathMask;
+
     void dump() const;
 
 private: