Add generic uniform setter function to SkRuntimeShaderBuilder

Change-Id: Idab539a4b39fe5ceab54948c99c0dcd6d19fd345
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/352743
Commit-Queue: Derek Sollenberger <djsollen@google.com>
Auto-Submit: Derek Sollenberger <djsollen@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>

include/effects/SkRuntimeEffect.h

@@ -222,6 +222,22 @@ public:
             return *this;
         }
 
+        template <typename T>
+        bool set(const T val[], const int count) {
+            static_assert(std::is_trivially_copyable<T>::value, "Value must be trivial copyable");
+            if (!fVar) {
+                SkDEBUGFAIL("Assigning to missing variable");
+                return false;
+            } else if (sizeof(T) * count != fVar->sizeInBytes()) {
+                SkDEBUGFAIL("Incorrect value size");
+                return false;
+            } else {
+                memcpy(SkTAddOffset<void>(fOwner->writableUniformData(), fVar->fOffset),
+                       val, sizeof(T) * count);
+            }
+            return true;
+        }
+
         SkRuntimeShaderBuilder*         fOwner;
         const SkRuntimeEffect::Uniform* fVar;    // nullptr if the variable was not found
     };

tests/SkRuntimeEffectTest.cpp

@@ -334,6 +334,35 @@ DEF_TEST(SkRuntimeShaderBuilderReuse, r) {
     auto shader_1 = b.makeShader(nullptr, true);
 }
 
+DEF_TEST(SkRuntimeShaderBuilderSetUniforms, r) {
+    const char* kSource = R"(
+        uniform half x;
+        uniform vec2 offset;
+        half4 main() { return half4(x); }
+    )";
+
+    sk_sp<SkRuntimeEffect> effect = std::get<0>(SkRuntimeEffect::Make(SkString(kSource)));
+    REPORTER_ASSERT(r, effect);
+
+    SkRuntimeShaderBuilder b(std::move(effect));
+
+    // Test passes if this sequence doesn't assert.
+    float x = 1.0f;
+    REPORTER_ASSERT(r, b.uniform("x").set(&x, 1));
+
+    // add extra value to ensure that set doesn't try to use sizeof(array)
+    float origin[] = { 2.0f, 3.0f, 4.0f };
+    REPORTER_ASSERT(r, b.uniform("offset").set<float>(origin, 2));
+
+#ifndef SK_DEBUG
+    REPORTER_ASSERT(r, !b.uniform("offset").set<float>(origin, 1));
+    REPORTER_ASSERT(r, !b.uniform("offset").set<float>(origin, 3));
+#endif
+
+
+    auto shader = b.makeShader(nullptr, false);
+}
+
 DEF_TEST(SkRuntimeEffectThreaded, r) {
     // SkRuntimeEffect uses a single compiler instance, but it's mutex locked.
     // This tests that we can safely use it from more than one thread, and also