[core] Implement circle-pitch-alignment property

Closes issue #9349.

2 files changed, 77 insertions, 0 deletions

diff --git a/platform/darwin/src/MGLCircleStyleLayer.h b/platform/darwin/src/MGLCircleStyleLayer.h
index 789ff7a258..ea95f6beef 100644
--- a/platform/darwin/src/MGLCircleStyleLayer.h
+++ b/platform/darwin/src/MGLCircleStyleLayer.h
@@ -8,6 +8,23 @@
 NS_ASSUME_NONNULL_BEGIN
 
 /**
+ Orientation of circle when map is pitched.
+
+ Values of this type are used in the `MGLCircleStyleLayer.circlePitchAlignment`
+ property.
+ */
+typedef NS_ENUM(NSUInteger, MGLCirclePitchAlignment) {
+    /**
+     The circle is aligned to the plane of the map.
+     */
+    MGLCirclePitchAlignmentMap,
+    /**
+     The circle is aligned to the plane of the viewport.
+     */
+    MGLCirclePitchAlignmentViewport,
+};
+
+/**
  Controls the scaling behavior of the circle when the map is pitched.
 
  Values of this type are used in the `MGLCircleStyleLayer.circleScaleAlignment`
@@ -221,6 +238,21 @@ MGL_EXPORT
 @property (nonatomic) MGLTransition circleOpacityTransition;
 
 /**
+ Orientation of circle when map is pitched.
+ 
+ The default value of this property is an `MGLStyleValue` object containing an
+ `NSValue` object containing `MGLCirclePitchAlignmentViewport`. Set this
+ property to `nil` to reset it to the default value.
+ 
+ You can set this property to an instance of:
+ 
+ * `MGLConstantStyleValue`
+ * `MGLCameraStyleFunction` with an interpolation mode of
+ `MGLInterpolationModeInterval`
+ */
+@property (nonatomic, null_resettable) MGLStyleValue<NSValue *> *circlePitchAlignment;
+
+/**
  Circle radius.
  
  This property is measured in points.
@@ -491,6 +523,19 @@ MGL_EXPORT
 #pragma mark Working with Circle Style Layer Attribute Values
 
 /**
+ Creates a new value object containing the given `MGLCirclePitchAlignment` enumeration.
+
+ @param circlePitchAlignment The value for the new object.
+ @return A new value object that contains the enumeration value.
+ */
++ (instancetype)valueWithMGLCirclePitchAlignment:(MGLCirclePitchAlignment)circlePitchAlignment;
+
+/**
+ The `MGLCirclePitchAlignment` enumeration representation of the value.
+ */
+@property (readonly) MGLCirclePitchAlignment MGLCirclePitchAlignmentValue;
+
+/**
  Creates a new value object containing the given `MGLCircleScaleAlignment` enumeration.
 
  @param circleScaleAlignment The value for the new object.
diff --git a/platform/darwin/src/MGLCircleStyleLayer.mm b/platform/darwin/src/MGLCircleStyleLayer.mm
index 42961f2e12..71ae37035e 100644
--- a/platform/darwin/src/MGLCircleStyleLayer.mm
+++ b/platform/darwin/src/MGLCircleStyleLayer.mm
@@ -13,6 +13,11 @@
 
 namespace mbgl {
 
+    MBGL_DEFINE_ENUM(MGLCirclePitchAlignment, {
+        { MGLCirclePitchAlignmentMap, "map" },
+        { MGLCirclePitchAlignmentViewport, "viewport" },
+    });
+
     MBGL_DEFINE_ENUM(MGLCircleScaleAlignment, {
         { MGLCircleScaleAlignmentMap, "map" },
         { MGLCircleScaleAlignmentViewport, "viewport" },
@@ -187,6 +192,23 @@ namespace mbgl {
     return transition;
 }
 
+- (void)setCirclePitchAlignment:(MGLStyleValue<NSValue *> *)circlePitchAlignment {
+    MGLAssertStyleLayerIsValid();
+
+    auto mbglValue = MGLStyleValueTransformer<mbgl::style::AlignmentType, NSValue *, mbgl::style::AlignmentType, MGLCirclePitchAlignment>().toEnumPropertyValue(circlePitchAlignment);
+    self.rawLayer->setCirclePitchAlignment(mbglValue);
+}
+
+- (MGLStyleValue<NSValue *> *)circlePitchAlignment {
+    MGLAssertStyleLayerIsValid();
+
+    auto propertyValue = self.rawLayer->getCirclePitchAlignment();
+    if (propertyValue.isUndefined()) {
+        return MGLStyleValueTransformer<mbgl::style::AlignmentType, NSValue *, mbgl::style::AlignmentType, MGLCirclePitchAlignment>().toEnumStyleValue(self.rawLayer->getDefaultCirclePitchAlignment());
+    }
+    return MGLStyleValueTransformer<mbgl::style::AlignmentType, NSValue *, mbgl::style::AlignmentType, MGLCirclePitchAlignment>().toEnumStyleValue(propertyValue);
+}
+
 - (void)setCircleRadius:(MGLStyleValue<NSNumber *> *)circleRadius {
     MGLAssertStyleLayerIsValid();
 
@@ -421,6 +443,16 @@ namespace mbgl {
 
 @implementation NSValue (MGLCircleStyleLayerAdditions)
 
++ (NSValue *)valueWithMGLCirclePitchAlignment:(MGLCirclePitchAlignment)circlePitchAlignment {
+    return [NSValue value:&circlePitchAlignment withObjCType:@encode(MGLCirclePitchAlignment)];
+}
+
+- (MGLCirclePitchAlignment)MGLCirclePitchAlignmentValue {
+    MGLCirclePitchAlignment circlePitchAlignment;
+    [self getValue:&circlePitchAlignment];
+    return circlePitchAlignment;
+}
+
 + (NSValue *)valueWithMGLCircleScaleAlignment:(MGLCircleScaleAlignment)circleScaleAlignment {
     return [NSValue value:&circleScaleAlignment withObjCType:@encode(MGLCircleScaleAlignment)];
 }