Refactoring of GPU NormalMap handling out into its own class

src/core/SkLightingShader.h

Index: src/core/SkLightingShader.h
diff --git a/src/core/SkLightingShader.h b/src/core/SkLightingShader.h
index f25b30342a70699506cc03a5ffbc786e1e620207..7f66aa9ee74e3f7eecc4ebc1f7f2265e25cf1b99 100644
--- a/src/core/SkLightingShader.h
+++ b/src/core/SkLightingShader.h
@@ -16,6 +16,34 @@ class SkMatrix;
 
 class SK_API SkLightingShader {
 public:
+    // TODO does this need to be tagged with SK_API?
+    class NormalSource : public SkFlattenable {

[egdaniel, 2016/06/10 14:23:28]

For SK_API, it is believed that having it on the outer class should extend it to
all the inner objects including nested classes. So for now lets leave it out,
put it becomes very obvious if certain builds fail that this is the issue and we
can add it back.

So talking with Mike Klein, we don't want this class to subclass SkFlattenable.
Instead just add functions (and just match Flattenable names) for the various
reads and writes for flattening. Then just call them from SkLightingShader's
flatten commands. This way you don't need this up in the enum.

[dvonbeck, 2016/06/10 15:22:29]

The problem with the approach you suggested is that normal source is an abstract
class. To be able to recreate it from a byte stream without subclassing
SkFlattenable I would need to encode the subclass in an enum that I set and then
have a switch statement that forks into the appropriate constructor, etc. I feel
like NormalSource should take advantage of the fact that serialization is
already implemented. Let me know what you think.

[dvonbeck, 2016/06/10 18:31:21]

Done.

+

[egdaniel, 2016/06/10 14:23:28]

remove \n between class and public

[dvonbeck, 2016/06/10 15:22:29]

Done.

+    public:
+
+        virtual ~NormalSource();
+
+        virtual sk_sp<GrFragmentProcessor> asFragmentProcessor(
+                GrContext* context,
+                const SkMatrix& viewM,
+                const SkMatrix* localMatrix,
+                SkFilterQuality filterQuality,
+                SkSourceGammaTreatment gammaTreatment) const = 0;
+
+
+        // SK_TO_STRING_VIRT() // TODO do I need this one? just copied from SkShader
+        SK_DEFINE_FLATTENABLE_TYPE(NormalSource)

[egdaniel, 2016/06/10 14:23:28]

These macros just declare/define various flattenable functions. If you want to
use the declare ones to get the names that is fine, or just declare them
manually yourself (especially since we won't be subclassing flattenable).

[dvonbeck, 2016/06/10 15:22:29]

Acknowledged.

+    };
+
+    class NormalMapSource {
+    public:
+        static sk_sp<NormalSource> Make(const SkBitmap& normal, const SkVector& invNormRotation,
+                                        const SkMatrix* normLocalM);
+
+        // TODO Why? Shouldn't the impls be registered?
+        SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
+    };
+
     /** Returns a shader that lights the diffuse and normal maps with a set of lights.
 
         It returns a shader with a reference count of 1.