API change to allow for NormalSource selection at the user level.

src/core/SkLightingShader.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkLightingShader_DEFINED
 #define SkLightingShader_DEFINED
 
 #include "SkLights.h"
 #include "SkShader.h"
 
 class SkBitmap;
 class SkMatrix;
+class SkNormalSource;
 
 class SK_API SkLightingShader {
 public:
-    /** Returns a shader that lights the diffuse and normal maps with a set of lights.
+    /** Returns a shader that lights the diffuse map using the normals and a set of lights.
 
         It returns a shader with a reference count of 1.
         The caller should decrement the shader's reference count when done with the shader.
         It is an error for count to be < 2.
         @param  diffuse     the diffuse bitmap
-        @param  normal      the normal map
         @param  lights       the lights applied to the normal map
-        @param  invNormRotation rotation applied to the normal map's normals
         @param  diffLocalMatrix the local matrix for the diffuse map (transform from
                                 texture coordinates to shape source coordinates). nullptr is
                                 interpreted as an identity matrix.
-        @param  normLocalMatrix the local matrix for the normal map (transform from
-                                texture coordinates to shape source coordinates). nullptr is
-                                interpreted as an identity matrix.
+        @param  normalSource the source for the normals
 
         nullptr will be returned if:
-            either 'diffuse' or 'normal' are empty
-            either 'diffuse' or 'normal' are too big (> 65535 on a side)
-            'diffuse' and 'normal' aren't the same size
+            'diffuse' is empty
+            'diffuse' is too big (> 65535 on any side)
 
         The lighting equation is currently:
             result = LightColor * DiffuseColor * (Normal * LightDir) + AmbientColor
 
-        The normal map is currently assumed to be an 8888 image where the normal at a texel
-        is retrieved by:
-            N.x = R-127;
-            N.y = G-127;
-            N.z = B-127;
-            N.normalize();
-        The +Z axis is thus encoded in RGB as (127, 127, 255) while the -Z axis is
-        (127, 127, 0).
     */
-    static sk_sp<SkShader> Make(const SkBitmap& diffuse, const SkBitmap& normal,
-                                sk_sp<SkLights> lights, const SkVector& invNormRotation,
-                                const SkMatrix* diffLocalMatrix, const SkMatrix* normLocalMatrix);
+    static sk_sp<SkShader> Make(const SkBitmap& diffuse, sk_sp<SkLights> lights,
+                                const SkMatrix* diffLocalMatrix,
+                                sk_sp<SkNormalSource> normalSource);
 
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
 };
 
 #endif