diff options
Diffstat (limited to 'include/mbgl/util/interpolate.hpp')
| -rw-r--r-- | include/mbgl/util/interpolate.hpp | 39 |
1 files changed, 38 insertions, 1 deletions
diff --git a/include/mbgl/util/interpolate.hpp b/include/mbgl/util/interpolate.hpp index a2103f18b2..aff730a0a2 100644 --- a/include/mbgl/util/interpolate.hpp +++ b/include/mbgl/util/interpolate.hpp @@ -3,6 +3,7 @@ #include <mbgl/util/color.hpp> #include <mbgl/util/range.hpp> #include <mbgl/style/position.hpp> +#include <mbgl/style/expression/value.hpp> #include <array> #include <vector> @@ -47,6 +48,36 @@ public: } }; + +// In order to accept Array<Number, N> as an output value for Curve +// expressions, we need to have an interpolatable std::vector type. +// However, style properties like line-dasharray are represented using +// std::vector<float>, and should NOT be considered interpolatable. +// So, we use std::vector<Value> to represent expression array values, +// asserting that (a) the vectors are the same size, and (b) they contain +// only numeric values. (These invariants should be relatively safe, +// being enforced by the expression type system.) +template<> +struct Interpolator<std::vector<style::expression::Value>> { + std::vector<style::expression::Value> operator()(const std::vector<style::expression::Value>& a, + const std::vector<style::expression::Value>& b, + const double t) const { + assert(a.size() == b.size()); + if (a.size() == 0) return {}; + std::vector<style::expression::Value> result; + for (std::size_t i = 0; i < a.size(); i++) { + assert(a[i].template is<double>()); + assert(b[i].template is<double>()); + style::expression::Value item = interpolate( + a[i].template get<double>(), + b[i].template get<double>(), + t); + result.push_back(item); + } + return result; + } +}; + template <> struct Interpolator<style::Position> { public: @@ -95,7 +126,13 @@ struct Interpolator<std::vector<T>> : Uninterpolated {}; template <class T> -constexpr bool Interpolatable = !std::is_base_of<Uninterpolated, Interpolator<T>>::value; +struct Interpolatable + : std::conditional_t< + !std::is_base_of<Uninterpolated, Interpolator<T>>::value, + std::true_type, + std::false_type> {}; + + } // namespace util } // namespace mbgl |