80 lines
1.8 KiB
C++
80 lines
1.8 KiB
C++
#ifndef MBGL_STYLE_FUNCTION_PROPERTIES
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#define MBGL_STYLE_FUNCTION_PROPERTIES
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#include <mbgl/util/variant.hpp>
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#include <vector>
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namespace mbgl {
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template <typename T>
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struct ConstantFunction {
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inline ConstantFunction(const T &value) : value(value) {}
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inline T evaluate(float) const { return value; }
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private:
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const T value;
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};
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template <typename T>
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struct LinearFunction {
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inline LinearFunction(const T &value, float z_base, float slope, const T &min, const T &max)
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: value(value), min(min), max(max), z_base(z_base), slope(slope) {}
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T evaluate(float z) const;
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private:
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const T value, min, max;
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const float z_base, slope;
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};
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template <typename T>
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struct ExponentialFunction {
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inline ExponentialFunction(const T &value, float z_base, float exp_base, float slope, const T &min,
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const T &max)
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: value(value), min(min), max(max), z_base(z_base), exp_base(exp_base), slope(slope) {}
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T evaluate(float z) const;
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private:
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const T value, min, max;
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const float z_base, exp_base, slope;
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};
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template <typename T>
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struct StopsFunction {
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inline StopsFunction(const std::vector<std::pair<float, T>> &values) : values(values) {}
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T evaluate(float z) const;
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private:
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const std::vector<std::pair<float, T>> values;
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};
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template <typename T>
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using Function = util::variant<
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std::false_type,
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ConstantFunction<T>,
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LinearFunction<T>,
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ExponentialFunction<T>,
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StopsFunction<T>
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>;
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template <typename T>
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struct FunctionEvaluator {
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typedef T result_type;
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inline FunctionEvaluator(float z) : z(z) {}
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inline result_type operator()(const std::false_type &) {
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return result_type();
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}
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template <template <typename> class Fn>
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inline result_type operator()(const Fn<T>& fn) {
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return fn.evaluate(z);
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}
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private:
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float z;
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};
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}
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#endif
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