Restore SkLightingShader and associated classes

This reverts https://skia-review.googlesource.com/c/skia/+/31140 (Remove SkLightingShader and associated classes) and updates the classes to ToT

Change-Id: I3b1df1704cca8907aa00f081a7e93339b65ad4fa
Reviewed-on: https://skia-review.googlesource.com/141545
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/src/shaders/SkLightingShader.h b/src/shaders/SkLightingShader.h
new file mode 100644
index 0000000000..62c881ccf6
--- /dev/null
+++ b/src/shaders/SkLightingShader.h
@@ -0,0 +1,40 @@
+/*
+ * 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 "SkFlattenablePriv.h"
+#include "SkLights.h"
+#include "SkShader.h"
+
+class SkBitmap;
+class SkMatrix;
+class SkNormalSource;
+
+class SK_API SkLightingShader {
+public:
+    /** Returns a shader that lights the shape, colored by the diffuseShader, using the
+        normals from normalSource, with the set of lights provided.
+
+        @param  diffuseShader     the shader that provides the colors. If nullptr, uses the paint's
+                                  color.
+        @param  normalSource      the source for the shape's normals. If nullptr, assumes straight
+                                  up normals (<0,0,1>).
+        @param  lights            the lights applied to the normals
+
+        The lighting equation is currently:
+            result = (LightColor * dot(Normal, LightDir) + AmbientColor) * DiffuseColor
+
+    */
+    static sk_sp<SkShader> Make(sk_sp<SkShader> diffuseShader, sk_sp<SkNormalSource> normalSource,
+                                sk_sp<SkLights> lights);
+
+    SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
+};
+
+#endif