Fabric: SharedColor for Android

Summary:
@public
On Android, a color can be represented as 32 bits integer, so there is no need to instantiate complex color objects and then pass them as shared pointers.  Hense instead of using shared_ptr, we use a simple wrapper class which provides a pointer-like interface.

Reviewed By: mdvacca

Differential Revision: D8742014

fbshipit-source-id: 14109b61fd84a34989538a15bc6fe4e2a8ce83a6

Author: shergin

ReactCommon/fabric/attributedstring/TextAttributes.h

@@ -31,8 +31,8 @@ class TextAttributes:
 #pragma mark - Fields
 
   // Color
-  SharedColor foregroundColor {nullptr};
-  SharedColor backgroundColor {nullptr};
+  SharedColor foregroundColor {};
+  SharedColor backgroundColor {};
   Float opacity {std::numeric_limits<Float>::quiet_NaN()};
 
   // Font
@@ -51,7 +51,7 @@ class TextAttributes:
   folly::Optional<WritingDirection> baseWritingDirection {};
 
   // Decoration
-  SharedColor textDecorationColor {nullptr};
+  SharedColor textDecorationColor {};
   folly::Optional<TextDecorationLineType> textDecorationLineType {};
   folly::Optional<TextDecorationLineStyle> textDecorationLineStyle {};
   folly::Optional<TextDecorationLinePattern> textDecorationLinePattern {};
@@ -60,7 +60,7 @@ class TextAttributes:
   // TODO: Use `Point` type instead of `Size` for `textShadowOffset` attribute.
   folly::Optional<Size> textShadowOffset {};
   Float textShadowRadius {std::numeric_limits<Float>::quiet_NaN()};
-  SharedColor textShadowColor {nullptr};
+  SharedColor textShadowColor {};
 
   // Special
   folly::Optional<bool> isHighlighted {};

ReactCommon/fabric/graphics/platform/android/Color.cpp

@@ -11,13 +11,22 @@ namespace facebook {
 namespace react {
 
 SharedColor colorFromComponents(ColorComponents components) {
-  // Not implemented.
-  return {};
+  return SharedColor(
+    ((int)components.alpha & 0xff) << 24 |
+    ((int)components.red & 0xff) << 16 |
+    ((int)components.green & 0xff) << 8 |
+    ((int)components.blue & 0xff)
+  );
 }
 
-ColorComponents colorComponentsFromColor(SharedColor color) {
-  // Not implemented.
-  return {};
+ColorComponents colorComponentsFromColor(SharedColor sharedColor) {
+  Color color = *sharedColor;
+  return ColorComponents {
+    (float)((color >> 16) & 0xff),
+    (float)((color >>  8) & 0xff),
+    (float)((color      ) & 0xff),
+    (float)((color >> 24) & 0xff)
+  };
 }
 
 } // namespace react

ReactCommon/fabric/graphics/platform/android/Color.h

@@ -7,15 +7,51 @@
 
 #pragma once
 
-#include <memory>
+#include <limits>
 
 #include <fabric/graphics/ColorComponents.h>
 
 namespace facebook {
 namespace react {
 
-using Color = float;
-using SharedColor = std::shared_ptr<Color>;
+using Color = int;
+
+/*
+ * On Android, a color can be represented as 32 bits integer, so there is no need
+ * to instantiate complex color objects and then pass them as shared pointers.
+ * Hense instead of using shared_ptr, we use a simple wrapper class
+ * which provides a pointer-like interface.
+ */
+class SharedColor {
+
+public:
+  static const Color UndefinedColor = std::numeric_limits<Color>::max();
+
+  SharedColor():
+    color_(UndefinedColor) {}
+
+  SharedColor(const SharedColor &sharedColor) :
+    color_(sharedColor.color_) {}
+
+  SharedColor(Color color):
+    color_(color) {}
+
+  SharedColor &operator=(const SharedColor &sharedColor) {
+    color_ = sharedColor.color_;
+    return *this;
+  }
+
+  Color operator*() const {
+    return color_;
+  }
+
+  operator bool() const {
+    return color_ != UndefinedColor;
+  }
+
+private:
+  Color color_;
+};
 
 SharedColor colorFromComponents(ColorComponents components);
 ColorComponents colorComponentsFromColor(SharedColor color);