[core] Introduce Layer::getPaintProperty() generic getter

13 files changed, 67 insertions, 8 deletions

diff --git a/include/mbgl/style/conversion_impl.hpp b/include/mbgl/style/conversion_impl.hpp
index 7ac4ec649b..866eff9eb5 100644
--- a/include/mbgl/style/conversion_impl.hpp
+++ b/include/mbgl/style/conversion_impl.hpp
@@ -2,7 +2,9 @@
 
 #include <mbgl/style/color_ramp_property_value.hpp>
 #include <mbgl/style/conversion.hpp>
+#include <mbgl/style/layer.hpp>
 #include <mbgl/style/property_value.hpp>
+#include <mbgl/style/transition_options.hpp>
 #include <mbgl/util/feature.hpp>
 #include <mbgl/util/geojson.hpp>
 #include <mbgl/util/optional.hpp>
@@ -10,6 +12,7 @@
 #include <mapbox/value.hpp>
 
 #include <array>
+#include <chrono>
 #include <string>
 #include <type_traits>
 
@@ -314,6 +317,18 @@ struct ValueFactory<ColorRampPropertyValue> {
 };
 
 template <>
+struct ValueFactory<TransitionOptions> {
+    static Value make(const TransitionOptions& value) {
+        return mapbox::base::ValueArray{
+            {std::chrono::duration_cast<std::chrono::milliseconds>(value.duration.value_or(mbgl::Duration::zero()))
+                 .count(),
+             std::chrono::duration_cast<std::chrono::milliseconds>(value.delay.value_or(mbgl::Duration::zero()))
+                 .count(),
+             value.enablePlacementTransitions}};
+    }
+};
+
+template <>
 struct ValueFactory<Color> {
     static Value make(const Color& color) { return color.toObject(); }
 };
@@ -334,10 +349,22 @@ Value makeValue(T&& arg) {
 }
 
 template <typename T>
-Value makeValue(const PropertyValue<T>& value) {
-    return value.match([](const Undefined&) -> Value { return {}; },
-                       [](const T& t) -> Value { return makeValue(t); },
-                       [](const PropertyExpression<T>& fn) { return fn.getExpression().serialize(); });
+LayerProperty makeLayerProperty(const PropertyValue<T>& value) {
+    return value.match([](const Undefined&) -> LayerProperty { return {}; },
+                       [](const T& t) -> LayerProperty {
+                           return {makeValue(t), LayerProperty::Kind::Constant};
+                       },
+                       [](const PropertyExpression<T>& fn) -> LayerProperty {
+                           return {fn.getExpression().serialize(), LayerProperty::Kind::Expression};
+                       });
+}
+
+inline LayerProperty makeLayerProperty(const TransitionOptions& value) {
+    return {makeValue(value), LayerProperty::Kind::Transition};
+}
+
+inline LayerProperty makeLayerProperty(const ColorRampPropertyValue& value) {
+    return {makeValue(value), LayerProperty::Kind::Expression};
 }
 
 } // namespace conversion
diff --git a/include/mbgl/style/layer.hpp b/include/mbgl/style/layer.hpp
index 35577411eb..646bad898c 100644
--- a/include/mbgl/style/layer.hpp
+++ b/include/mbgl/style/layer.hpp
@@ -1,9 +1,10 @@
 #pragma once
 
+#include <mbgl/style/conversion.hpp>
+#include <mbgl/style/types.hpp>
+#include <mbgl/util/feature.hpp>
 #include <mbgl/util/immutable.hpp>
 #include <mbgl/util/optional.hpp>
-#include <mbgl/style/types.hpp>
-#include <mbgl/style/conversion.hpp>
 
 #include <mapbox/weak.hpp>
 #include <mapbox/type_wrapper.hpp>
@@ -65,6 +66,14 @@ struct LayerTypeInfo {
     const enum class TileKind : uint8_t { Geometry, Raster, RasterDEM, NotRequired } tileKind;
 };
 
+struct LayerProperty {
+    enum class Kind : uint8_t { Undefined, Constant, Expression, Transition };
+    LayerProperty(Value value_, Kind kind_) : value(std::move(value_)), kind(kind_) {}
+    LayerProperty() = default;
+    const Value value;
+    const Kind kind = Kind::Undefined;
+};
+
 /**
  * The runtime representation of a [layer](https://www.mapbox.com/mapbox-gl-style-spec/#layers) from the Mapbox Style
  * Specification.
@@ -110,9 +119,12 @@ public:
 
     // Dynamic properties
     virtual optional<conversion::Error> setLayoutProperty(const std::string& name, const conversion::Convertible& value) = 0;
-    virtual optional<conversion::Error> setPaintProperty(const std::string& name, const conversion::Convertible& value) = 0;
+    virtual optional<conversion::Error> setPaintProperty(const std::string& name,
+                                                         const conversion::Convertible& value) = 0;
     optional<conversion::Error> setVisibility(const conversion::Convertible& value);
 
+    virtual LayerProperty getPaintProperty(const std::string&) const = 0;
+
     // Private implementation
     // TODO : We should not have public mutable data members.
     class Impl;
diff --git a/include/mbgl/style/layers/background_layer.hpp b/include/mbgl/style/layers/background_layer.hpp
index 4a73ae4a0b..8caade26b0 100644
--- a/include/mbgl/style/layers/background_layer.hpp
+++ b/include/mbgl/style/layers/background_layer.hpp
@@ -24,6 +24,8 @@ public:
     optional<conversion::Error> setLayoutProperty(const std::string& name, const conversion::Convertible& value) final;
     optional<conversion::Error> setPaintProperty(const std::string& name, const conversion::Convertible& value) final;
 
+    LayerProperty getPaintProperty(const std::string& name) const final;
+
     // Paint properties
 
     static PropertyValue<Color> getDefaultBackgroundColor();
diff --git a/include/mbgl/style/layers/circle_layer.hpp b/include/mbgl/style/layers/circle_layer.hpp
index f171805806..be4fe5cee4 100644
--- a/include/mbgl/style/layers/circle_layer.hpp
+++ b/include/mbgl/style/layers/circle_layer.hpp
@@ -24,6 +24,8 @@ public:
     optional<conversion::Error> setLayoutProperty(const std::string& name, const conversion::Convertible& value) final;
     optional<conversion::Error> setPaintProperty(const std::string& name, const conversion::Convertible& value) final;
 
+    LayerProperty getPaintProperty(const std::string& name) const final;
+
     // Paint properties
 
     static PropertyValue<float> getDefaultCircleBlur();
diff --git a/include/mbgl/style/layers/custom_layer.hpp b/include/mbgl/style/layers/custom_layer.hpp
index 4ae59dfae3..9ae68c4fff 100644
--- a/include/mbgl/style/layers/custom_layer.hpp
+++ b/include/mbgl/style/layers/custom_layer.hpp
@@ -71,7 +71,7 @@ public:
     // Dynamic properties
     optional<conversion::Error> setLayoutProperty(const std::string& name, const conversion::Convertible& value) final;
     optional<conversion::Error> setPaintProperty(const std::string& name, const conversion::Convertible& value) final;
-
+    LayerProperty getPaintProperty(const std::string&) const final;
     // Private implementation
 
     class Impl;
diff --git a/include/mbgl/style/layers/fill_extrusion_layer.hpp b/include/mbgl/style/layers/fill_extrusion_layer.hpp
index 2e89032ae7..63ccf369d4 100644
--- a/include/mbgl/style/layers/fill_extrusion_layer.hpp
+++ b/include/mbgl/style/layers/fill_extrusion_layer.hpp
@@ -24,6 +24,8 @@ public:
     optional<conversion::Error> setLayoutProperty(const std::string& name, const conversion::Convertible& value) final;
     optional<conversion::Error> setPaintProperty(const std::string& name, const conversion::Convertible& value) final;
 
+    LayerProperty getPaintProperty(const std::string& name) const final;
+
     // Paint properties
 
     static PropertyValue<float> getDefaultFillExtrusionBase();
diff --git a/include/mbgl/style/layers/fill_layer.hpp b/include/mbgl/style/layers/fill_layer.hpp
index 0c4369de4c..acf60cec0d 100644
--- a/include/mbgl/style/layers/fill_layer.hpp
+++ b/include/mbgl/style/layers/fill_layer.hpp
@@ -24,6 +24,8 @@ public:
     optional<conversion::Error> setLayoutProperty(const std::string& name, const conversion::Convertible& value) final;
     optional<conversion::Error> setPaintProperty(const std::string& name, const conversion::Convertible& value) final;
 
+    LayerProperty getPaintProperty(const std::string& name) const final;
+
     // Paint properties
 
     static PropertyValue<bool> getDefaultFillAntialias();
diff --git a/include/mbgl/style/layers/heatmap_layer.hpp b/include/mbgl/style/layers/heatmap_layer.hpp
index 2023d8c21e..7eb7bb8edd 100644
--- a/include/mbgl/style/layers/heatmap_layer.hpp
+++ b/include/mbgl/style/layers/heatmap_layer.hpp
@@ -25,6 +25,8 @@ public:
     optional<conversion::Error> setLayoutProperty(const std::string& name, const conversion::Convertible& value) final;
     optional<conversion::Error> setPaintProperty(const std::string& name, const conversion::Convertible& value) final;
 
+    LayerProperty getPaintProperty(const std::string& name) const final;
+
     // Paint properties
 
     static ColorRampPropertyValue getDefaultHeatmapColor();
diff --git a/include/mbgl/style/layers/hillshade_layer.hpp b/include/mbgl/style/layers/hillshade_layer.hpp
index f6b04a0062..7c8f6fa573 100644
--- a/include/mbgl/style/layers/hillshade_layer.hpp
+++ b/include/mbgl/style/layers/hillshade_layer.hpp
@@ -24,6 +24,8 @@ public:
     optional<conversion::Error> setLayoutProperty(const std::string& name, const conversion::Convertible& value) final;
     optional<conversion::Error> setPaintProperty(const std::string& name, const conversion::Convertible& value) final;
 
+    LayerProperty getPaintProperty(const std::string& name) const final;
+
     // Paint properties
 
     static PropertyValue<Color> getDefaultHillshadeAccentColor();
diff --git a/include/mbgl/style/layers/layer.hpp.ejs b/include/mbgl/style/layers/layer.hpp.ejs
index 638db5fe4b..f678adeda7 100644
--- a/include/mbgl/style/layers/layer.hpp.ejs
+++ b/include/mbgl/style/layers/layer.hpp.ejs
@@ -40,6 +40,8 @@ public:
     optional<conversion::Error> setLayoutProperty(const std::string& name, const conversion::Convertible& value) final;
     optional<conversion::Error> setPaintProperty(const std::string& name, const conversion::Convertible& value) final;
 
+    LayerProperty getPaintProperty(const std::string& name) const final;
+
 <% if (layoutProperties.length) { -%>
     // Layout properties
 
diff --git a/include/mbgl/style/layers/line_layer.hpp b/include/mbgl/style/layers/line_layer.hpp
index 8f1d51295c..a1c69e9475 100644
--- a/include/mbgl/style/layers/line_layer.hpp
+++ b/include/mbgl/style/layers/line_layer.hpp
@@ -27,6 +27,8 @@ public:
     optional<conversion::Error> setLayoutProperty(const std::string& name, const conversion::Convertible& value) final;
     optional<conversion::Error> setPaintProperty(const std::string& name, const conversion::Convertible& value) final;
 
+    LayerProperty getPaintProperty(const std::string& name) const final;
+
     // Layout properties
 
     static PropertyValue<LineCapType> getDefaultLineCap();
diff --git a/include/mbgl/style/layers/raster_layer.hpp b/include/mbgl/style/layers/raster_layer.hpp
index ba2ea45428..e516e1a0fc 100644
--- a/include/mbgl/style/layers/raster_layer.hpp
+++ b/include/mbgl/style/layers/raster_layer.hpp
@@ -24,6 +24,8 @@ public:
     optional<conversion::Error> setLayoutProperty(const std::string& name, const conversion::Convertible& value) final;
     optional<conversion::Error> setPaintProperty(const std::string& name, const conversion::Convertible& value) final;
 
+    LayerProperty getPaintProperty(const std::string& name) const final;
+
     // Paint properties
 
     static PropertyValue<float> getDefaultRasterBrightnessMax();
diff --git a/include/mbgl/style/layers/symbol_layer.hpp b/include/mbgl/style/layers/symbol_layer.hpp
index b60e991f49..578d7d1701 100644
--- a/include/mbgl/style/layers/symbol_layer.hpp
+++ b/include/mbgl/style/layers/symbol_layer.hpp
@@ -26,6 +26,8 @@ public:
     optional<conversion::Error> setLayoutProperty(const std::string& name, const conversion::Convertible& value) final;
     optional<conversion::Error> setPaintProperty(const std::string& name, const conversion::Convertible& value) final;
 
+    LayerProperty getPaintProperty(const std::string& name) const final;
+
     // Layout properties
 
     static PropertyValue<bool> getDefaultIconAllowOverlap();