From cf37e87df42bcf740d2b093212bef5ac794d235f Mon Sep 17 00:00:00 2001
From: jmkiley <jordan.kiley@mapbox.com>
Date: Wed, 19 Feb 2020 11:11:59 -0800
Subject: [ios] Add separate mgl_color conversion method for expressions

---
 platform/darwin/src/MGLStyleValue_Private.h |  2 +-
 platform/ios/app/MBXViewController.m        | 16 ++++++++++------
 platform/ios/src/UIColor+MGLAdditions.h     |  2 ++
 platform/ios/src/UIColor+MGLAdditions.mm    |  8 ++++++++
 4 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/platform/darwin/src/MGLStyleValue_Private.h b/platform/darwin/src/MGLStyleValue_Private.h
index 43f0b9d282..3b14ea700b 100644
--- a/platform/darwin/src/MGLStyleValue_Private.h
+++ b/platform/darwin/src/MGLStyleValue_Private.h
@@ -214,7 +214,7 @@ private: // Private utilities for converting from mgl to mbgl values
 
     // Color
     void getMBGLValue(MGLColor *rawValue, mbgl::Color &mbglValue) {
-        mbglValue = rawValue.mgl_color;
+        mbglValue = rawValue.mgl_colorForPremultipliedValue;
     }
 
     // Image
diff --git a/platform/ios/app/MBXViewController.m b/platform/ios/app/MBXViewController.m
index 82a68e074a..e308b9f582 100644
--- a/platform/ios/app/MBXViewController.m
+++ b/platform/ios/app/MBXViewController.m
@@ -1014,11 +1014,11 @@ CLLocationCoordinate2D randomWorldCoordinate() {
 - (void)styleWaterLayer
 {
     MGLFillStyleLayer *waterLayer = (MGLFillStyleLayer *)[self.mapView.style layerWithIdentifier:@"water"];
-    NSDictionary *waterColorStops = @{@6.0f: [UIColor yellowColor],
-                                      @8.0f: [UIColor blueColor],
-                                      @10.0f: [UIColor redColor],
-                                      @12.0f: [UIColor greenColor],
-                                      @14.0f: [UIColor blueColor]};
+    NSDictionary *waterColorStops = @{@6.0f: [[UIColor yellowColor] colorWithAlphaComponent:0.5],
+                                      @8.0f: [[UIColor blueColor] colorWithAlphaComponent:0.5],
+                                      @10.0f: [[UIColor redColor] colorWithAlphaComponent:0.5],
+                                      @12.0f: [[UIColor greenColor] colorWithAlphaComponent:0.5],
+                                      @14.0f: [[UIColor blueColor] colorWithAlphaComponent:0.5]};
     NSExpression *fillColorExpression = [NSExpression mgl_expressionForInterpolatingExpression:NSExpression.zoomLevelVariableExpression
                                                                                  withCurveType:MGLExpressionInterpolationModeLinear
                                                                                     parameters:nil
@@ -1084,9 +1084,13 @@ CLLocationCoordinate2D randomWorldCoordinate() {
     [self.mapView.style addSource:source];
 
     MGLFillStyleLayer *fillLayer = [[MGLFillStyleLayer alloc] initWithIdentifier:@"test" source:source];
-    fillLayer.fillColor = [NSExpression expressionForConstantValue:[UIColor purpleColor]];
+    fillLayer.fillColor = [NSExpression expressionForConstantValue:[[UIColor blueColor] colorWithAlphaComponent:0.75]];
     [self.mapView.style addLayer:fillLayer];
+    [self.mapView setCenterCoordinate:CLLocationCoordinate2DMake(52.3667, 4.8945) zoomLevel:9 animated:NO];
 
+    UIView *blueView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 120, 140)];
+    blueView.backgroundColor = [[UIColor blueColor] colorWithAlphaComponent:0.75];
+    [self.view addSubview:blueView];
 }
 
 - (void)styleSymbolLayer
diff --git a/platform/ios/src/UIColor+MGLAdditions.h b/platform/ios/src/UIColor+MGLAdditions.h
index 19702fa105..86c8daff59 100644
--- a/platform/ios/src/UIColor+MGLAdditions.h
+++ b/platform/ios/src/UIColor+MGLAdditions.h
@@ -7,6 +7,8 @@
 
 - (mbgl::Color)mgl_color;
 
+- (mbgl::Color)mgl_colorForPremultipliedValue;
+
 - (mbgl::style::PropertyValue<mbgl::Color>)mgl_colorPropertyValue;
 
 + (UIColor *)mgl_colorWithColor:(mbgl::Color)color;
diff --git a/platform/ios/src/UIColor+MGLAdditions.mm b/platform/ios/src/UIColor+MGLAdditions.mm
index 68e77f5b10..281ac79ba8 100644
--- a/platform/ios/src/UIColor+MGLAdditions.mm
+++ b/platform/ios/src/UIColor+MGLAdditions.mm
@@ -12,6 +12,14 @@
     return { static_cast<float>(r*a), static_cast<float>(g*a), static_cast<float>(b*a), static_cast<float>(a) };
 }
 
+- (mbgl::Color)mgl_colorForPremultipliedValue
+{
+    CGFloat r, g, b, a;
+    [self getRed:&r green:&g blue:&b alpha:&a];
+    
+    return { static_cast<float>(r), static_cast<float>(g), static_cast<float>(b), static_cast<float>(a) };
+}
+
 - (mbgl::style::PropertyValue<mbgl::Color>)mgl_colorPropertyValue
 {
     mbgl::Color color = self.mgl_color;
-- 
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