From da95eca6356ec90260d7ac4205a06d04f9959c3d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Minh=20Nguy=E1=BB=85n?= <mxn@1ec5.org>
Date: Fri, 30 Mar 2018 03:21:44 -0700
Subject: [core] Fixed to-rgba with zero opacity

---
 include/mbgl/util/color.hpp                       |  2 ++
 mapbox-gl-js                                      |  2 +-
 src/mbgl/style/expression/compound_expression.cpp |  7 +------
 src/mbgl/style/expression/value.cpp               |  9 +++++----
 src/mbgl/util/color.cpp                           | 22 ++++++++++++++++++----
 5 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/include/mbgl/util/color.hpp b/include/mbgl/util/color.hpp
index 300d7fae82..01a4c8f292 100644
--- a/include/mbgl/util/color.hpp
+++ b/include/mbgl/util/color.hpp
@@ -4,6 +4,7 @@
 
 #include <cassert>
 #include <string>
+#include <array>
 
 namespace mbgl {
 
@@ -37,6 +38,7 @@ public:
 
     static optional<Color> parse(const std::string&);
     std::string stringify() const;
+    std::array<double, 4> toArray() const;
 };
 
 inline bool operator==(const Color& colorA, const Color& colorB) {
diff --git a/mapbox-gl-js b/mapbox-gl-js
index 34902f8db3..bbee7e5169 160000
--- a/mapbox-gl-js
+++ b/mapbox-gl-js
@@ -1 +1 @@
-Subproject commit 34902f8db3f8a3757a465d62a96b8fa731ee1461
+Subproject commit bbee7e51695184e9b3c0ecb74d314c4ab73d4c27
diff --git a/src/mbgl/style/expression/compound_expression.cpp b/src/mbgl/style/expression/compound_expression.cpp
index b1c2d74a9f..77b294b380 100644
--- a/src/mbgl/style/expression/compound_expression.cpp
+++ b/src/mbgl/style/expression/compound_expression.cpp
@@ -209,12 +209,7 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
         );
     });
     define("to-rgba", [](const Color& color) -> Result<std::array<double, 4>> {
-        return std::array<double, 4> {{ 
-            255 * color.r / color.a, 
-            255 * color.g / color.a,
-            255 * color.b / color.a, 
-            color.a 
-        }};
+        return color.toArray();
     });
     
     define("rgba", rgba);
diff --git a/src/mbgl/style/expression/value.cpp b/src/mbgl/style/expression/value.cpp
index 72779d4956..627f6f92e8 100644
--- a/src/mbgl/style/expression/value.cpp
+++ b/src/mbgl/style/expression/value.cpp
@@ -106,12 +106,13 @@ Value ValueConverter<mbgl::Value>::toExpressionValue(const mbgl::Value& value) {
 mbgl::Value ValueConverter<mbgl::Value>::fromExpressionValue(const Value& value) {
     return value.match(
         [&](const Color& color)->mbgl::Value {
+            auto array = color.toArray();
             return std::vector<mbgl::Value>{
                 std::string("rgba"),
-                double(255 * color.r / color.a),
-                double(255 * color.g / color.a),
-                double(255 * color.b / color.a),
-                double(color.a)
+                array[0],
+                array[1],
+                array[2],
+                array[3],
             };
         },
         [&](const std::vector<Value>& values)->mbgl::Value {
diff --git a/src/mbgl/util/color.cpp b/src/mbgl/util/color.cpp
index c8145d36e7..ab311382b5 100644
--- a/src/mbgl/util/color.cpp
+++ b/src/mbgl/util/color.cpp
@@ -23,11 +23,25 @@ optional<Color> Color::parse(const std::string& s) {
 }
 
 std::string Color::stringify() const {
+    auto array = toArray();
     return "rgba(" +
-        util::toString(r * 255 / a) + "," +
-        util::toString(g * 255 / a) + "," +
-        util::toString(b * 255 / a) + "," +
-        util::toString(a) + ")";
+        util::toString(array[0]) + "," +
+        util::toString(array[1]) + "," +
+        util::toString(array[2]) + "," +
+        util::toString(array[3]) + ")";
+}
+
+std::array<double, 4> Color::toArray() const {
+    if (a == 0) {
+        return {{}};
+    } else {
+        return {{
+            r * 255 / a,
+            g * 255 / a,
+            b * 255 / a,
+            a,
+        }};
+    }
 }
 
 } // namespace mbgl
-- 
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