[core] Fix alpha handling in rgba and to-rgba operatorsupstream/fix-10604

2 files changed, 7 insertions, 4 deletions

diff --git a/src/mbgl/style/expression/compound_expression.cpp b/src/mbgl/style/expression/compound_expression.cpp
index 70bc6dfd95..e5f849144b 100644
--- a/src/mbgl/style/expression/compound_expression.cpp
+++ b/src/mbgl/style/expression/compound_expression.cpp
@@ -216,7 +216,12 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
         );
     });
     define("to-rgba", [](const Color& color) -> Result<std::array<double, 4>> {
-        return std::array<double, 4> {{ color.r, color.g, color.b, color.a }};
+        return std::array<double, 4> {{ 
+            255 * color.r / color.a, 
+            255 * color.g / color.a,
+            255 * color.b / color.a, 
+            color.a 
+        }};
     });
     
     define("rgba", rgba);
diff --git a/src/mbgl/style/expression/util.cpp b/src/mbgl/style/expression/util.cpp
index f198fb3e1b..ee680dab08 100644
--- a/src/mbgl/style/expression/util.cpp
+++ b/src/mbgl/style/expression/util.cpp
@@ -1,4 +1,3 @@
-
 #include <mbgl/style/expression/util.hpp>
 #include <mbgl/style/expression/value.hpp>
 
@@ -30,10 +29,9 @@ Result<Color> rgba(double r, double g, double b, double a) {
             "]: 'a' must be between 0 and 1."
         };
     }
-    return Color(r / 255, g / 255, b / 255, a);
+    return Color(r / 255 * a, g / 255 * a, b / 255 * a, a);
 }
 
 } // namespace expression
 } // namespace style
 } // namespace mbgl
-