1 files changed, 45 insertions, 2 deletions
diff --git a/platform/macos/src/NSColor+MGLAdditions.mm b/platform/macos/src/NSColor+MGLAdditions.mm
index e80a2910f8..4ffc1ef0b2 100644
--- a/platform/macos/src/NSColor+MGLAdditions.mm
+++ b/platform/macos/src/NSColor+MGLAdditions.mm
@@ -37,13 +37,56 @@
 @implementation NSExpression (MGLColorAdditions)
 
 + (NSExpression *)mgl_expressionForRGBComponents:(NSArray<NSExpression *> *)components {
+    if (NSColor *color = [self mgl_colorWithComponentExpressions:components]) {
+        return [NSExpression expressionForConstantValue:color];
+    }
+    
     NSExpression *color = [NSExpression expressionForConstantValue:[NSColor class]];
-    return [NSExpression expressionForFunction:color selectorName:@"colorWithCalibratedRed:green:blue:" arguments:components];
+    NSExpression *alpha = [NSExpression expressionForConstantValue:@1.0];
+    return [NSExpression expressionForFunction:color
+                                  selectorName:@"colorWithRed:green:blue:alpha:"
+                                     arguments:[components arrayByAddingObject:alpha]];
 }
 
 + (NSExpression *)mgl_expressionForRGBAComponents:(NSArray<NSExpression *> *)components {
+    if (NSColor *color = [self mgl_colorWithComponentExpressions:components]) {
+        return [NSExpression expressionForConstantValue:color];
+    }
+    
     NSExpression *color = [NSExpression expressionForConstantValue:[NSColor class]];
-    return [NSExpression expressionForFunction:color selectorName:@"colorWithCalibratedRed:green:blue:alpha:" arguments:components];
+    return [NSExpression expressionForFunction:color
+                                  selectorName:@"colorWithRed:green:blue:alpha:"
+                                     arguments:components];
+}
+
+/**
+ Returns a color object corresponding to the given component expressions.
+ */
++ (NSColor *)mgl_colorWithComponentExpressions:(NSArray<NSExpression *> *)componentExpressions {
+    // Map the component expressions to constant components. If any component is
+    // a non-constant expression, the components cannot be converted into a
+    // constant color value.
+    std::vector<CGFloat> components;
+    for (NSExpression *componentExpression in componentExpressions) {
+        if (componentExpression.expressionType != NSConstantValueExpressionType) {
+            return nil;
+        }
+        
+        NSNumber *component = (NSNumber *)componentExpression.constantValue;
+        if (![component isKindOfClass:[NSNumber class]]) {
+            return nil;
+        }
+        
+        components.push_back(component.doubleValue / 255.0);
+    }
+    // Alpha
+    components.back() *= 255.0;
+    
+    // The Mapbox Style Specification does not specify a color space, but it is
+    // assumed to be sRGB for consistency with CSS.
+    return [NSColor colorWithColorSpace:[NSColorSpace sRGBColorSpace]
+                             components:&components[0]
+                                  count:components.size()];
 }
 
 @end