diff options
Diffstat (limited to 'src/mbgl/renderer/possibly_evaluated_property_value.hpp')
-rw-r--r-- | src/mbgl/renderer/possibly_evaluated_property_value.hpp | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/src/mbgl/renderer/possibly_evaluated_property_value.hpp b/src/mbgl/renderer/possibly_evaluated_property_value.hpp new file mode 100644 index 0000000000..a0bcec2bf1 --- /dev/null +++ b/src/mbgl/renderer/possibly_evaluated_property_value.hpp @@ -0,0 +1,74 @@ +#pragma once + +#include <mbgl/style/function/source_function.hpp> +#include <mbgl/style/function/composite_function.hpp> +#include <mbgl/util/interpolate.hpp> +#include <mbgl/util/variant.hpp> + +namespace mbgl { + +template <class T> +class PossiblyEvaluatedPropertyValue { +private: + using Value = variant< + T, + style::SourceFunction<T>, + style::CompositeFunction<T>>; + + Value value; + +public: + PossiblyEvaluatedPropertyValue() = default; + PossiblyEvaluatedPropertyValue(Value v) : value(std::move(v)) {} + + bool isConstant() const { + return value.template is<T>(); + } + + optional<T> constant() const { + return value.match( + [&] (const T& t) { return optional<T>(t); }, + [&] (const auto&) { return optional<T>(); }); + } + + T constantOr(const T& t) const { + return constant().value_or(t); + } + + template <class... Ts> + auto match(Ts&&... ts) const { + return value.match(std::forward<Ts>(ts)...); + } + + template <class Feature> + T evaluate(const Feature& feature, float zoom, T defaultValue) const { + return this->match( + [&] (const T& constant) { return constant; }, + [&] (const style::SourceFunction<T>& function) { + return function.evaluate(feature, defaultValue); + }, + [&] (const style::CompositeFunction<T>& function) { + return function.evaluate(zoom, feature, defaultValue); + } + ); + } +}; + +namespace util { + +template <typename T> +struct Interpolator<PossiblyEvaluatedPropertyValue<T>> { + PossiblyEvaluatedPropertyValue<T> operator()(const PossiblyEvaluatedPropertyValue<T>& a, + const PossiblyEvaluatedPropertyValue<T>& b, + const double t) const { + if (a.isConstant() && b.isConstant()) { + return { interpolate(*a.constant(), *b.constant(), t) }; + } else { + return { a }; + } + } +}; + +} // namespace util + +} // namespace mbgl |